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    12 January 2023, Volume 49 Issue 1
    • REVIEWS
      Current situation, issues, and prospects of breeding and approval of new varieties of nutrition-oriented crops
      ZHU Da-Zhou, WU Ning, ZHANG Yong, SUN Jun-Mao, CHEN Meng-Shan
      Acta Agronomica Sinica. 2023, 49(1):  1-11.  doi:10.3724/SP.J.1006.2023.23018
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      With China’s economic and social development and the continuous improvement of people’s living standards, the consumers’ diet preference has switched from purely pursuing food taste to more nutrition and health demand, resulting in an urgent need for a transformation and upgrading of the current dietary structure to match the new trend. Correspondingly, nutrition and health-oriented crop breeding is imperative. This review aims to elaborate the research progresses in nutrition-oriented crop breeding in the world with the evolving goals of crop breeding in China, to sort out the nutritional quality indicators dominating in crop breeding globally, and to analyze the problems in existing nutritional indicators involved in the approval of new crop varieties in China. In conclusions, nutritional indicators combined with the consumer nutritional demand are put forward to the current examination and verification system of existing and new crop varieties in China and thus to promote the rapid development of crop nutritional breeding and support the nutrition demand of consumers and the construction of “Healthy China” from the source.

      Physiological mechanism and regulation effect of low light on maize yield formation
      SUN Zhi-Chao, ZHANG Ji-Wang
      Acta Agronomica Sinica. 2023, 49(1):  12-23.  doi:10.3724/SP.J.1006.2023.13064
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      As for global climate change, insufficient light during the growth periods has become one of the main factors restricting maize yield, increasing the risk of global food production and nutritional security. In this study, based on the previous experiments, we explored the physiological mechanism of low light on maize yield formation from the aspects of photosynthetic performance, nutrient absorption characteristics, grain formation, and filling characteristics. Under low light stress, the light harvesting ability of leaves was reduced, the stromal and grana thylakoids disintegrated, the activities of related enzymes were reduced, the photosystem was damaged, and the carbon assimilation ability was reduced, which further inhibited root development, significantly affected root morphology and function, and was not conducive to nutrient absorption and metabolism. Due to the insufficient nutrition supply, the development of tassel and ear was blocked, the morphological function of pollen and filaments was affected, resulting in low flower fertilization rate and decreased grain number per ear. Low light also reduced the number of endosperm cells— “sink” capacity, the structure and function of the endosperm transfer cells were affected, the endogenous hormonal balance was broken, sucrose, starch metabolism related enzyme activity decreased, internodes vascular bundle number and area reduced, transport and transformation ability were limited, eventualy led to the poor state of starch and the decreased grain weight significantly. Therefore, to alleviate the influence of low light stress on maize yield formation, it is urgent to establish indexes for systematic evaluation of shade tolerance varieties, accelerate the cultivation of new shade-tolerant varieties with high light efficiency by modern technology, and adopt cultivation measures such as increasing nitrogen fertilizer application, removing top leaves, spraying growth regulator and foliar fertilizer to improve maize yield. In the future, more attention should focus on root-shoot coordination and deeply explore the mechanism of low light stress, so as to provide the theoretical basis for the establishment of key techniques of maize resistance to yield increase.

      CROP GENETICS & BREEDING · GERMPLASM RESOURCES · MOLECULAR GENETICS
      Function of GmPIN2 family gene in regulating root development in soybean
      LIANG Zheng, KE Mei-Yu, CHEN Zhi-Wei, CHEN Xu, GAO Zhen
      Acta Agronomica Sinica. 2023, 49(1):  24-35.  doi:10.3724/SP.J.1006.2023.14233
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      Auxin is one of the important plant hormones. Auxin transport is involved in the regulation of plant tissue and organ development. In Arabidopsis thaliana, auxin transport is mainly regulated by PIN family proteins, among which AtPIN2 controls auxin basipetal transport and regulates root gravitation in Arabidopsis. However, GmPIN2 family proteins and their functions are still largely unknown in soybean. In this study, we identified two AtPIN2 homologous genes of GmPIN2a and GmPIN2b through phylogenetic and protein domain analysis. The relative expression level showed that GmPIN2a and GmPIN2b were highly expressed in root and nodule. Both genes were highly expressed in root epidermis and cortex, and the vascular bundles of the root nodule. Only GmPIN2a expressed in the epidermis and outer cortex at the tip of the root nodule. Furthermore, Gmpin2ab mutants were generated by CRISPR/Cas9 (Clustered Regularly Interspersed Short Palindromic Repeats/CRISPR Associated 9) gene editing technology. Gmpin2ab mutants had a significant loss of root gravitropism. Moreover, the loss of Gmpin2 resulted in a significant decrease of root area and lateral root length, while the lateral root angle of Gmpin2ab significantly increased. Overexpression of GmPIN2b also resulted in a decrease in root area and lateral root length, but the lateral root angle unchanged. In conclusion, GmPIN2a and GmPIN2b play important roles in regulation of soybean root development via mediating auxin basipetal transport. This study laid a foundation for further analysis of the function and mechanism of GmPIN proteins in soybean root morphogenesis.

      Relative expression analysis of StMAPKK4 gene and screening and identification of its interacting proteins in potato (Solanum tuberosum L.)
      PU Xue, WANG Kai-Tong, ZHANG Ning, SI Huai-Jun
      Acta Agronomica Sinica. 2023, 49(1):  36-45.  doi:10.3724/SP.J.1006.2023.24006
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      MAPKKs, one of the main members of mitogen-activated protein kinase (MAPK) cascade, are located in the middle of the cascade pathway and play a key role in signal transduction. Studies have shown that potato StMAPKK4 gene responds to drought stress. To further explore the biological function of StMAPKK4 gene, bioinformatics analysis was conducted in the study. The results showed that StMAPKK4 was most closely related to Solanum commersonii. It contained the protein kinase domain (PF00069) of the protein kinase family, which located between 64 aa and 302 aa. StMAPKK4 contained multiple hormones (methyl jasmonate, ethylene, and abscisic acid) and stress-related response elements. The qRT-PCR analysis revealed that StMAPKK4 gene expression was the highest in potato stem. The relative expression levels were up-regulated under drought and salt treatments. Subcellular localization indicated that StMAPKK4 was localized on the cell membrane. Furthermore, eight proteins interacting with StMAPKK4 were screened by yeast two-hybrid method, and their interaction was verified by rotation experiment. Blast comparison of the interacting proteins indicated that StMAPKK4 interacted with polyphenol oxidase, phycocyanin, aspartate aminotransferase, osmotin, phosphate transporter, and other proteins. It was preliminarily concluded that StMAPKK4 may be involved in the response mechanism of photosynthesis, a series of abiotic stresses such as low temperature, drought, and salt stresses in plants, and promote the uptake of phosphorus in roots.

      Genome-wide identification of NAC transcription factors ATAF subfamily in Sacchrum spontaneum and functional analysis of its homologous gene ScNAC2 in sugarcane cultivar
      WANG Heng-Bo, ZHANG Chang, WU Ming-Xing, LI Xiang, JIANG Zhong-Li, LIN Rong-Xiao, GUO Jin-Long, QUE You-Xiong
      Acta Agronomica Sinica. 2023, 49(1):  46-61.  doi:10.3724/SP.J.1006.2023.24005
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      NAC (NAM, ATAF, and CUC) is a family of transcription factors unique to terrestrial plants, including 18 subfamilies, of which ATAF subfamily members are mainly involved in the response processes of biotic and abiotic stresses, such as salicylic acid (SA), methyl jasmonate acid (MeJA), abscisic acid (ABA), pathogenic bacteria, mechanical damage, low temperature, and sodium chloride (NaCl). The data were from the genomic database of Saccharum spontaneum and the cDNA library of a sugarcane cultivar ROC22. Firstly, the ATAF subfamily members in Saccharum were identified and analyzed for their protein multiple sequence alignment, phylogenetic tree construction, and promoter region cis-acting element prediction using comparative genomics methods and various bioinformatics methods. Secondly, one homologous gene of the ATAF subfamily SsNAC2, ScNAC2, was cloned from a prevalent sugarcane cultivar ROC22 in China. The qRT-PCR was used to detect the tissue-specific expression pattern and the relative expression levels of ScNAC2 gene under different exogenous stresses. Finally, the subcellular localization and the transactivation analysis of ScNAC2 protein were performed. The results showed that six members of the ATAF subfamily were identified with the open read reading frames between 889 bp and 1017 bp, relative molecular weights between 32.067 and 35.819 kD, the theoretical isoelectric points from 5.09 to 8.92, and the proteins of all members were predicted to localize on the nucleus. In addition, the Ka/Ks ratios of six gene pairs were all less than 1, indicating that purification selection played an important role during evolution. The amino acid sequence alignment indicated that all members of the ATAF subfamily contained the NAM conserved domains, consisting of I, II, III, IV, and V subdomains. Phylogenetic analysis revealed that the members from sugarcane, sorghum, maize, and rice, that belonged to Gramineae, were clustered together, indicating that they had a close evolutionary relationship. Forty members of the ATAF subfamily from Arabidopsis, rice, maize, and sorghum were divided into two groups (Group A and Group B), in which the subfamily members of maize had obvious gene expansion. Furthermore, the promoter regions of ATAF subfamily members all contained cis-acting elements that responded to stresses such as low temperature, drought, and hormones, and we thus speculated that they were involved in the response processes of a variety of biotic and abiotic stresses. Furthermore, the full-length cDNA sequence of the ScNAC2 gene (GenBank accession number: OL982539) was cloned from the sugarcane cultivar ROC22, with an open reading frame of 891 bp and encoding 296 amino acid residues. The similarity of amino acid sequence between ScNAC2 and SsNAC2 proteins both from ATAF subfamily Group B was 97.99%. The qRT-PCR showed that the ScNAC2 gene was constitutively expressed in different tissues of sugarcane, and its expression level in sugarcane leaves and stem epidermis was higher than that in stem piths, buds, and roots. Besides, the relative expression level of ScNAC2 gene was significantly down-regulated under SA and MeJA stresses, however, it showed an expression pattern from low to high and varied to significant levels under the stress of ABA, 4℃, and NaCl. Subcellular localization revealed that the ScNAC2-GFP fusion protein was localized in the cell nucleus of Nicotiana benthamiana leaves. Furthermore, the transactivation experiment showed that ScNAC2 protein did not have the transcriptional self-activation activity. The above results established the foundation for identifying the biological functions of sugarcane NAC-ATAF subfamily members in response to biotic and abiotic stresses and provided potential genetic resources for sugarcane resistance molecular breeding.

      Analysis of key genes involved in GA pathway responding to temperature and exogenous GA related to internode development in soybean
      QI Yang-Yang, DOU Ru-Na, ZHAO Cai-Tong, ZHANG Zhi, LI Wen-Bin, JIANG Zhen-Feng
      Acta Agronomica Sinica. 2023, 49(1):  62-72.  doi:10.3724/SP.J.1006.2023.24007
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      The objective of this study is to explore the effects of temperature and exogenous GA on the development of soybean internode and the key genes related to gibberellin (GA) signal transduction pathway. The soybean variety ‘Charleston’ was grown in chambers or in pots under outdoor condition, and subjected to the treatments with different temperature and concentration of GA solutions. Phenotype observation, section with hand, LC-MS analysis, and RNA-seq experiments were performed to investigate the internode changes and the genes involved in the GA signal transduction pathway. Different temperature and exogenous GA all induced the internode elongation and the longer the length increased, the slender the internode became. Exogenous GA had an evident elongating effect on the cell length of the internode despite of no effect on the cell width. The internodes grown in 30℃ growth condition were longer than those in 25℃ growth condition. GA2-oxidase, GA19, GA53, GA20, and bioactive GA3 were detected in the elongation zone of soybean internode, suggesting that GA2-oxidase might play an important role in the developmental process of soybean internode. Tissue-specific genes in DELLA, GAI, and PIF gene families could be identified and facilitate the gene selection to regulate the internode growth and plant height from GA signal transduction pathway. Soybean internode was regulated by temperature and exogenous GA. From GA53 to GA19 to GA20 and ultimately to GA3 was an important GA synthesis pathway. GA2-oxidase played an important role on the internode development of soybean. The GA-GID1-DELLA complex was expressed specifically in soybean internode. The candidate genes related to the internode development could be filtered from GID1 and DELLA gene family.

      Genome-wide identification and relative expression analysis of DGATs gene family in sunflower
      ZHANG Cheng, ZHANG Zhan, YANG Jia-Bao, MENG Wan-Qiu, ZENG Ling-Lu, SUN Li
      Acta Agronomica Sinica. 2023, 49(1):  73-85.  doi:10.3724/SP.J.1006.2023.14217
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      Diacylglycerol acyltransferase (DGAT) plays an important role in plant oil metabolism and stress resistance. To explore the evolution of DGAT gene in sunflower (Helianthus annuus L.) and its function in oil biosynthesis and response to abiotic stresses, 18 homologous gene sequences of DGAT were obtained from the sunflower genome database by alignment with Arabidopsis thaliana AtDGATs genes. Then, chromosome distribution, gene structure, conserved protein motifs, phylogenetic relationship, tissue-specific expression of HaDGATs, and their expressing patterns under abiotic stresses were systematically investigated. The results showed that sunflower DGATs genes were divided into four subfamilies (DGAT1, DGAT2, DGAT3, and WSD), and the members of the same subfamily shared similar gene structures and conserved motifs. The promoter regions of HaDGATs harbored multiple cis-elements related to environmental stresses and plant hormone response. The main factor for HaDGATs amplification was fragment duplication. The qRT-PCR indicated that HaDGAT1, HaDGAT2, and HaDGAT3 were mainly expressed in the early and middle stages of sunflower seed development, which coincided with the rapid accumulation period of oil in seeds, while HaWSD subfamily genes were mainly expressed in stems, leaves, and petals. Most of HaWSD genes could be induced by NaCl, low temperature, drought, and ABA treatments in sunflower roots, stems, and leaves, indicating that they might play essential roles in dealing with various abiotic stresses. The results revealed that HaDGATs had functional differentiation in regulating lipid biosynthesis and abiotic stresses. This study provides an important foundation for further understanding the function of sunflower DGAT genes.

      Genome-wide association analysis of indica-rice heading date based on NCII genetic mating design
      XU Kai, ZHENG Xing-Fei, ZHANG Hong-Yan, HU Zhong-Li, NING Zi-Lan, LI Lan-Zhi
      Acta Agronomica Sinica. 2023, 49(1):  86-96.  doi:10.3724/SP.J.1006.2023.12079
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      Heading date is jointly regulated by light and temperature resources and gene network, affecting crop yield and regional adaptability of varieties. Identification of significant loci and genes associated with trait variation by genome-wide association analysis (GWAS) is of great significance to analyze the genetic basis of the heading date in rice. In this study, according to the North Carolina design II (NCII), 115 indica rice varieties as the male parents and 5 sterile lines as the female parents had been made test cross, and 575 F1 test-cross lines were obtained. GWAS was performed on the phenotypic value of the heading date of the male parental varieties (V) and testcross lines (TC), the general combining ability (GCA) of the male parent lines, the special combining ability (SCA), and better parent heterosis (BPH) of testcross lines. (1) A total of 104 significantly associated locus were located and distributed on 12 chromosomes. Of these, 16 significantly associated locus were detected on chromosome 4. There were six, five, fifteen, fifty-seven, and twenty-one significantly associated locus detected in V, GCA, TC, SCA, BPH data sets, respectively. Phenotypic variation analysis of significantly associated sites in these five data sets revealed that the total contribution rate (phenotypic variation explained, PVE) of significantly associated loci to phenotypic variation in V, GCA, TC, SCA, and BPH data sets was 79.57%, 10.51%, 33.35%, 56.42%, and 54.86%, respectively. Twenty-five significantly associated locus were simultaneously detected in two or more than two datasets, that probably was hotspot genomic region of heading date in rice. (2) By comparing all significantly associated locus with the annotation information of the Nipponbare reference genome, five cloned genes related to heading date were found. Among them, three of the five genes within 200 kb from the significantly associated locus detected in this study. Compared with the haplotype combinations in the three genes with the superior haplotype of individual clone gene, we found that the average grain yield per plant of male parental varieties with the haplotype combination SDG724 (Hap. A)_Hd17 (Hap. E)_Ghd7 (Hap. A) was higher and the heading date period was longer. The results indicated that the pyramiding superior haplotype of genes related to heading date would extend the heading date period of conventional rice varieties and improve their yield. However, the situation was different for testcross population, the haplotype combination form of SDG724 (Hap. I)_Hd17 (Hap. K)_Ghd7 (Hap. I) had the superior yield but median heading date period. None superior haplotype pyramiding resulting in high yield or long heading date was found in the testcross lines population, indicating that the genetic basis of heading date of testcross hybrids was more complicated than rice varieties. The combination of genome-wide association analysis and haplotype analysis can utilize the linkage disequilibrium information provided by multiple SNPs, which improves the efficiency of gene detection and facilitates the cultivation of high-yield rice varieties.

      Gene cloning and expression analysis of ScPR10 in sugarcane under Acidovorax avenae subsp. avenae infection
      LI Juan, ZHOU Jing-Ru, CHU Na, SUN Hui-Dong, HUANG Mei-Ting, FU Hua-Ying, GAO San-Ji
      Acta Agronomica Sinica. 2023, 49(1):  97-104.  doi:10.3724/SP.J.1006.2023.14239
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      PR10 is a pathogenesis-related protein (PR), which plays critical roles in the growth and development and various environmental stress responses in plants. This study demonstrated that two ScPR10 genes were cloned from the leaf samples of ROC22 (resistant to red stripe) and Mintang 11-610 (susceptible to red stripe) by RT-PCR, and then RT-qPCR, transcriptome, and proteomics assays were carried out to explore the expression patterns of two genes in varieties ROC22 and Mintang 11-610 post inoculation with red stripe pathogen Acidovorax avenae subsp. avenae (Aaa). Sequence analysis showed that the two ScPR10 genes encoding 187 amino acids had more 27 amino acids than PR10 proteins from other plants, which contained the conserved domains P-loop and Bet v 1. ScPR10 obtained in this study shared high homology with these published PR10 proteins encoded by Saccharum spp., Sorghum bicolor, and Erianthus arundinaceus. The RT-qPCR analysis showed that the relative expression levels of ScPR10 genes were significantly increased by 27.2 times and 39.7 times in the resistant and susceptible varieties under Aaa infection, especially at 24 hours post inoculation (24 hpi), compared with the controls (0 hpi), respectively. Meanwhile, the transcriptome data revealed that the relative expression levels of ScPR10 genes were significantly increased by 5.3-5.4 folds [log2(Fold Change)] in the two varieties under Aaa infection, particular at 72 hours post inoculation (72 hpi). Prediction of protein interaction revealed that ScPR10 would interact with the pleiotropic drug resistance (PDR) protein of ABCG transporter subfamily (Cluster-13677.282407) and protein kinase (Cluster-13677.166559). Proteomics analysis referred that the relative expression of ScPR10 proteins were increased by 1.65-1.69 folds (log2FC) evaluated by 24 hpi versus 0 hpi in resistant and susceptible varieties. Similarly, the relative expression levels of the ABC transporter (Cluster-13677.282407) were upregulated to a certain extent in two varieties, but the relative expression levels of protein kinase (Cluster-13677.166559) were only enhanced in Mintang 11-610, not in ROC22. In conclusion, the ScPR10 may synergize with the ABC transporter (Cluster-13677.282407) involving in the defense response in sugarcane in response to Aaa infection.

      Transcriptional expression profiling of soybean genes under sulfur-starved conditions by RNA-seq
      WANG Hui, WU Zhi-Yi, ZHANG Yu-E, YU De-Yue
      Acta Agronomica Sinica. 2023, 49(1):  105-118.  doi:10.3724/SP.J.1006.2023.24004
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      Soybean is an important grain and oil crop. Few researches focused on soybean sulfur utilization. Here, the tolerance of Yunmengliuyuehuaye (YM) and Qinyangdadou (QY) to low sulfur were evaluated. The gene expression profiles of roots and leaves of the two materials under the control (+S) and sulfur deficiency (-S) environments were analyzed via RNA resequencing. The results showed that YM was tolerance to low sulfur and QY was susceptibility to low sulfur. 9064 and 9795 differentially expressed genes (DEGs) were identified in leaves of YM and QY, and 3185 and 5006 DEGs were identified in roots of YM and QY, respectively. KEGG enrichment revealed that nine pathways were common in the two material leaves, of which MAPK signaling pathway—plant specially enriched more upregulated expressed genes. There were 18 common pathways in both roots. Nine of them responded consistently to low sulfur in YM and QY, of which four contained more up-regulated genes and five contained more downregulated genes. In the remaining nine pathways, YM contained more upregulated expressed genes. Soybean sulfate transporter genes were important for the absorption and transportation of sulfate. In the transcriptome, 27 soybean sulfate transporter genes were identified. These genes belonged to 4 subgroups respectively. Most of the genes in subgroups 1, 2, and 4 were induced by low sulfur, and the genes in subgroup 3 responded to low sulfur in a complex way. KEGG showed that the upregulated gene of GmEIL1 (ethylene-insensitive 3-like) in the MAPK signaling pathway-plant was clone. The gene was involved in the regulation of soybean sulfur utilization in the soybean chimeras with transgenic hairy root. These results provide a basis for deeply exploring the genetic mechanism of soybean sulfur utilization efficiency and candidate genes for soybean tolerance to low sulfate breeding in the future.

      Mapping of QTLs for heading date of rice with high-density bin genetic map
      ZHAO Ling, LIANG Wen-Hua, ZHAO Chun-Fang, WEI Xiao-Dong, ZHOU Li-Hui, YAO Shu, WANG Cai-Lin, ZHANG Ya-Dong
      Acta Agronomica Sinica. 2023, 49(1):  119-128.  doi:10.3724/SP.J.1006.2023.12089
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      Identification of new loci and genes related to heading date is very important for the genetic mechanism research and molecular improvement in rice. A recombinant inbred lines (RILs) was developed by crossing the japonica rice TD70 and the indica rice Kasalath with obvious difference in heading date. A high-density genetic linkage map with 12,328 recombination Bin markers was constructed based on the re-sequencing data of parents and RILs. The RILs and two parents were planted at the Jiangsu Academy of Agricultural Sciences, in Nanjing in 2018 and 2021. QTLs that controlled the heading date were analyzed by IciMappingv3.4 software with inclusive compound interval mapping method. 15 QTLs related to heading date of rice were detected, distributed on chromosome 3, 6, 7, 8, 10, and 12 in two years. The phenotype variation explained (PVE) and LOD value of single QTL ranged from 3.29%-14.73% and 2.58-10.68, respectively. Among them, seven QTLs were found to locate in the same interval or adjacent to previously QTLs, and four QTLs were detected in two years indicating their genetic stability. According to the annotation and sequences analysis of genes located in the region of repeatable QTLs, we found that seven annotated genes had non-synonymous mutations in the coding regions between TD70 and Kasalath. Based on the mutations in the coding regions, the haplotypes of seven genes were identified in RIL population. The heading date of RILs had significant difference between the RILs with different haplotype of four genes, indicating that they might be the candidate genes for heading date. These results could be useful for subsequent functional studies and molecular marker assisted breeding of heading date.

      Functional identification of sucrose transporter protein IbSWEET15 in sweet potato
      WU Xu-Li, WU Zheng-Dan, WAN Chuan-Fang, DU Ye, GAO Yan, LI Ze-Xuan, WANG Zhi-Qian, TANG Dao-Bin, WANG Ji-Chun, ZHANG Kai
      Acta Agronomica Sinica. 2023, 49(1):  129-139.  doi:10.3724/SP.J.1006.2023.24023
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      SWEET proteins play important regulatory roles in plant growth and development, stress response and sugar metabolism, but few research has been reported on SWEET proteins in sweet potato. It is of great theoretical and practical significance to carry out functional studies on sweet potato SWEET proteins to reveal their functions in sugar transport and starch and sugar metabolism. Based on the transcripts of SWEET encoding gene differentially expressed in sweet potato storage roots with different starch-related traits, specific primers were designed and the full-length cDNA sequence of IbSWEET15 was cloned using RACE method. IbSWEET15 bioinformatics was performed using online software, and its classification was clarified by phylogenetic tree analysis. The subcellular localization of the protein encoded by IbSWEET15 gene was identified by transient expression of IbSWEET15-GFP fusion protein in Nicotiana benthamiana, while yeast mutant complementation experiments were carried out to identify the sugar transport function of IbSWEET15 in yeast. The relative expression pattern of IbSWEET15 genes in various organs of sweet potato were analyzed by qRT-PCR. IbSWEET15 expression vector was constructed and transformed into Arabidopsis wild-type Col-0 by floral dip method to obtain IbSWEET15 heterologously expressed Arabidopsis lines, and the starch and sugar contents of the transgenic plants were measured and compared with those of wild-type Arabidopsis plants, and the function of IbSWEET15 in starch and sugar metabolism was identified. IbSWEET15, with an open reading frame of 879 bp, encoded a 292 amino acid sucrose transporter protein with two MtN3_slv conserved structural domains and seven transmembrane structural domains, and was a member of clade III of the SWEET protein family. The protein encoded by IbSWEET15 localized at the plasma membrane and did not transport sucrose and hexose in yeast mutant. IbSWEET15 gene had the highest expression in sweet potato branches, followed by stems and leaves, and the lowest expression in storage roots. The leaf soluble sugar contents of the IbSWEET15 heterologously expressed Arabidopsis lines were significantly decreased, while the seed soluble sugar and starch contents were higher than wild type. We proposed that IbSWEET15 played an important role in phloem loading during the source to sink transport of photosynthetic product as well as sugar and starch accumulation. This study provides the critical information for understanding the function of IbSWEET15 in starch and sugar metabolism, and formation of important quality traits in sweet potato.

      Genome-wide association study and candidate gene prediction of kernel starch content in maize
      WANG Rui-Pu, DONG Zhen-Ying, GAO Yue-Xin, BAO Jian-Xi, YIN Fang-Bing, LI Jin-Ping, LONG Yan, WAN Xiang-Yuan
      Acta Agronomica Sinica. 2023, 49(1):  140-152.  doi:10.3724/SP.J.1006.2023.23020
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      Maize is an important food crop worldwide, and about 70% of its grain weight comes from starch. Starch is not only the main energy resource for human and other animals but also an important raw material for chemical industries. In this study, an association panel including 711 maize inbred lines was used for the examination of both wet-base starch content and dry-base starch content of maize kernel from two environments combined with 2799 single nucleotide polymorphism (SNP) markers spaning the whole genome of maize, genome-wide association study (GWAS) was carried out using FarmCPU model. 67 significant SNPs were identified, of which 23 highly reliable significant SNPs (HRS-SNPs) could be repeatedly associated in different environments. Three HRS-SNPs were reported for the first time by our study, and the remaining 20 HRS-SNPs were either located within the known quantitative trait loci (QTLs) or within 1 Mb of known SNPs associated with mazie kernel starch content. Through gene function annotation, gene ontology (GO) analysis and gene expression analysis, a total of 45 important candidate genes, involving starch biosynthesis, carbohydrate metabolism, sugar metabolism, hormone metabolism, and other pathways were identified within 200 kb regions around the HRS-SNPs. And two genes Ae1 and Pin1 which had been reported to regulate the maize kernel starch content were also detected. Furthermore, elite alles of the nine major SNPs was identified by allelic variation effect analysis. Our study provides new genetic information for further disecting the genetic mechanism of maize kernel starch content and provides important gene resources for accelerating the breeding of new maize varieties with high yield and quality.

      Protein and physiological differences under cold stress, and identification and analysis of BnGSTs in Brassica napus L.
      MA Li, BAI Jing, ZHAO Yu-Hong, SUN Bo-Lin, HOU Xian-Fei, FANG Yan, WANG Wang-Tian, PU Yuan-Yuan, LIU Li-Jun, XU Jia, TAO Xiao-Lei, SUN Wan-Cang, WU Jun-Yan
      Acta Agronomica Sinica. 2023, 49(1):  153-166.  doi:10.3724/SP.J.1006.2023.14207
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      Glutathione S-transferases (GST) are involved in regulating many aspects of plant growth, development, and response to adversity stress. In this study, the differentially expressed proteins of ‘16VHNTS309’ under cold stress were analyzed using bidirectional electrophoresis and mass spectrometry, and proteins involved in the cold stress response, such as BE, APX, SOD, and GST, were identified based on GO and KEGG analyses. The key protein GST was identified using qRT-PCR and physiological indicators in response to cold stress, and the GST gene of ‘16VHNTS309’ was cloned using homologous cloning. This gene CDS length was 642 bp, and encoded 213 amino acids, which was an unstable protein and belonged to the GST_N_3 glutathione S-transferase family. The sequence similarity with Brassica napus ‘ZS11’ was 99.22%, and a comparison of the amino acid sequences of both ‘ZS11’ and ‘Vision’ revealed a mutation from leucine (L) to proline (P) at position 127. The gene family analysis showed that 153 BnGSTs members were identified in Brassica napus and were classified into seven main types according to their functions: Zeta, Phi, Theta, CHQ, DHAR, Lambda, and Tau. Most BnGSTs belonged to Phi and Tau types. Phylogeny divided BnGSTs into 12 subfamilies, subfamilies I and VIII contained more members. BnGSTs were unevenly distributed on 18 chromosomes, and the number of BNGSTs genes on C06 chromosome was the largest, it contained 10 conserved protein motifs. There were 99 pairs of genes in the BnGSTs gene family that were colinearly related, 131 genes from gene duplication events, and segmental duplication events played an important role in the evolution of BnGSTs genes. Significantly higher expression of BnaA02g35760D, BnaC06g20450D, BnaC06g35490D, BnaA02g03230D, and BnaA02g35980D in strong cold-resistant varieties was 7-12 times higher than that in weak cold-resistant varieties under cold stress. And the strong cold-resistant varieties had higher physiological enzyme activities. In addition, a number of key candidate genes were identified for transient and sustained expression under freezing stress. This result lays the foundation for further studies on the molecular regulation of BnGSTs genes for cold resistance in strong cold resistant for Brassica napus.

      TILLAGE & CULTIVATION · PHYSIOLOGY & BIOCHEMISTRY
      Spatiotemporal variation of high temperature stress in different regions of China under climate change
      SHANG Meng-Fei, SHI Xiao-Yu, ZHAO Jiong-Chao, LI Shuo, CHU Qing-Quan
      Acta Agronomica Sinica. 2023, 49(1):  167-176.  doi:10.3724/SP.J.1006.2023.23007
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      Analysing the spatial-temporal distribution and the change of high temperature damage during crop growth period is of great significance for developing management techniques of crop cultivation under climate change. Based on the daily data of 558 meteorological stations and maize phenology period in China, we explored the spatiotemporal variation of heat degree days (HDD) and its trend of different maize growth periods from 1961 to 2020. The results showed that the HDD exhibited a general increased trend during the whole growth period and every growth stage of maize in China from 1961 to 2020, with HDD increased 1.19-9.27℃ d (10a)-1 of different farming regions. The HDD increase range was higher in Sichuan Basin farming region, south China farming region and northwest farming region, and it increased significantly by 8.79, 9.27, and 5.81℃ d (10a)-1, respectively. The change trend of HDD at different growth stages had obvious variation in different regions. HDD increased greatly in the early growth period of northern farming regions, while HDD increased greatly in late growth period of southern farming regions. During maize sowing-tassel period, the HDD increased significantly by 2.67 and 2.00℃ d (10a)-1 in northwest farming region and north China farming region, respectively, and it increased by 1.41℃ d (10a)-1 in Huang-Huai-Hai farming region, both of them were higher than that in other farming regions. During tassel-milk period, the HDD of southern farming regions increased greatly, which increased significantly by 3.68 and 2.11℃ d (10a)-1 in south China farming region and Sichuan Basin farming region, respectively. During milk-maturity period, the HDD of southern farming regions increased higher by 0.88-5.31℃ d (10a)-1 than -0.01-0.59℃ d (10a)-1 in northern farming regions. In conclusion, to cope with the increasing risk of high temperature stress of maize, northern farming regions should focus on the impact of high temperature during maize sowing-milk period, and southern farming regions should focus on the impact of high temperature after maize tasseled.

      Spatial-temporal variations for agronomic and quality characters of soybeans varieties (strains) tested in America from 1991 to 2019
      BAI Zhi-Yuan, CHEN Xiang-Yang, ZHENG A-Xiang, ZHANG Li, ZOU Jun, ZHANG Da-Tong, CHEN Fu, YIN Xiao-Gang
      Acta Agronomica Sinica. 2023, 49(1):  177-187.  doi:10.3724/SP.J.1006.2023.24026
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      America is an important soybean producer in the world, and there is a large gap in terms of soybean production level between China and America. It is of great significance to explore the spatial-temporal evolution patterns of the main characters of American soybean varieties in China’s soybean production. This study was based on the observation data of 102,244 variety-site-year observations from 213 soybean regional test sites in America from 1991 to 2019, which explored the spatial-temporal variations of agronomic and quality traits of American soybean regional trial varieties (strains) during the recent 30 years by using linear regression model, spatial analysis and structural equation model. The results showed that: (1) The number of soybean regional test varieties (strains) and soybean yield in America had an upward trend from 1991 to 2019, soybean yield was stable with the mean value of 3000 kg hm-2 from 1991 to 2003, which increased significantly with an average annual rate of 46.4 kg hm-2 since 2004, and the average soybean yield was 3525 kg hm-2 during the recent 15 years; the western-corn belt and eastern-corn belt were the high soybean yield regions in America, the yield level higher than 4000 kg hm-2 accounting for 22.6% of the regional test sites from 2004 to 2019, which was mainly distributed in the western-corn belt and eastern-corn belt. (2) The 100-grain weight of American soybean varieties (strains) had a downward trend during the recent 30 years, but there were no significant changes in plant height and growth period; specifically, the 100-grain weight decreased by 0.12 g per year from 1991 to 2003, while it kept stable since 2004. (3) In the recent 30 years, the protein content of American soybean regional test varieties (strains) experienced decreasing trend, and the average protein content decreased from 41.3% in 1991-2003 to 40.0% in 2004-2019, the protein content in the southern America was 1.4% higher than the northern parts; the oil content indicated decreasing trend while showed increasing trend afterwards, the average oil content increased from 20.3% in the 1991-2003 period to 21.3% in the 2004-2019 period; 59.2% of the regional test sites in America had soybean oil content higher than 21% from 2004 to 2019. (4) The yield level and oil content of American soybean regional test varieties (strains) increased synergistically from 2004 to 2019, while the restrictive effects of soybean agronomic traits on yield decreased. This study revealed the spatial-temporal variations of agronomic and quality traits of soybean varieties (strains) during the recent 30 years, and determined the constraint relationship between yield and various traits of regional trial varieties (strains) of American soybean in different periods, which could provide references for the coordinated development of high-yield and high-quality of soybean in China.

      Relationship between root architecture and root pulling force of summer maize
      ZHANG Jing, WANG Hong-Zhang, REN Hao, YIN Fu-Wei, WU Hong-Yan, ZHAO Bin, ZHANG Ji-Wang, REN Bai-Zhao, DAI Ai-Bin, LIU Peng
      Acta Agronomica Sinica. 2023, 49(1):  188-199.  doi:10.3724/SP.J.1006.2023.23004
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      To screen out the summer maize varieties with high root-lodging resistance and provide theoretical basis for the breeding of root-toppling resistance maize varieties to achieve resistant to lodging and high and stable yields in summer maize, the relationship between root architecture and root-lodging resistance was studied. In this experiment, to analyze the relationship between root morphology and root lodging resistance, 104 summer maize varieties widely planted in Yellow-Huaihe-Haihe Rivers region were used as materials, and the root pulling force and root related characters of different maize varieties were measured at flowering stage, and were evaluated by principal component analysis and cluster analysis. The results showed that the root pulling force of 104 varieties conformed to normal distribution with a range of 862-1092 N. There was a significant positive correlation between root pulling force and root angle, root numbers, total root number, root length, root dry weight, and yields. Based on the comprehensive root traits of different maize varieties, the experimental varieties were group into six groups according to the root lodging resistance from strong to weak. Among them, the varieties with strong root resistance were as follows: Lianyan 155, Dika 517, Qiminyu 6, Jinhai 13, Laiyu 721, Fengle 365, Liangxing 579, Denghai 605, Denghai 518, and Dedan 179. This group of maize varieties had the characteristics of higher root dry weight, root number, total root number, root angle, root length, and grain yield.

      Effects of nitrogen panicle fertilizer application on physicochemical properties and fine structure of japonica rice starch and its relationship with eating quality
      JIANG Yan, ZHAO Can, CHEN Yue, LIU Guang-Ming, ZHAO Ling-Tian, LIAO Ping-Qiang, WANG Wei-Ling, XU Ke, LI Guo-Hui, WU Wen-Ge, HUO Zhong-Yang
      Acta Agronomica Sinica. 2023, 49(1):  200-210.  doi:10.3724/SP.J.1006.2023.12083
      Abstract ( 357 )   HTML ( 27 )   PDF (578KB) ( 324 )   Save
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      To clarify the variations of physicochemical properties and the fine structure of japonica rice starch under different nitrogen panicle fertilizer treatment and to explore the relationship between eating quality and starch properties and structure, three panicle fertilizer nitrogen application levels (0, 45, and 135 kg N hm-2) were set under same basal and tiller fertilizer with Nanjing 9108 and Nanjing 0212 as the materials. Starch properties and structure of japonica rice under different treatments were determined, and the relationship between starch characteristics and eating quality was examined. The result indicated that application of nitrogen panicle fertilizer reduced the eating value of japonica rice, and there was significant difference in the high nitrogen treatment. Hardness, resilience, the absolute value of stickiness and balance, and the total protein content increased as nitrogen application rate were increased, while the apparent amylose content had the opposite trend. In terms of starch properties and structure, application of nitrogen panicle fertilizer increased starch solubility and swelling power, gelatinization enthalpy, small starch granules, relative crystallinity, and infrared ratio of 1045/1022 cm-1, while decreased retrogradation enthalpy and percentage, large starch granules, starch average diameter and infrared ratio of 1022/995 cm-1, and the trend appeared obvious especially under high nitrogen treatment. In conclusion, applying nitrogen panicle fertilizer can reduce the apparent amylose content, improve the surface order of starch and the stability of crystal region, decrease the starch granules size, thereby hindering the starch swelling and gelatinization, leading to the increase of rice hardness, eventually deteriorating the eating quality. Appropriate application of nitrogen panicle fertilizer can realize the coordination of excellent quality and high yield of japonica rice.

      Effect of amount of nitrogen fertilizer applied on photosynthetic physiological characteristics of drip irrigated spring wheat leaves
      WANG Hai-Qi, WANG Rong-Rong, JIANG Gui-Ying, YIN Hao-Jie, YAN Shi-Jie, CHE Zi-Qiang
      Acta Agronomica Sinica. 2023, 49(1):  211-224.  doi:10.3724/SP.J.1006.2023.11100
      Abstract ( 385 )   HTML ( 18 )   PDF (1736KB) ( 390 )   Save
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      The objective of this study is to clarify the regulatory effects of different N fertilizer applications on photosynthetic characteristics and assimilate accumulation in drip irrigated spring wheat leaves under the climatic conditions of northern Xinjiang. A split-zone experimental design was used to investigate the effects of N application on the photosynthetic enzyme activities, gas exchange parameters, chlorophyll fluorescence parameters, dry matter accumulation partitioning, and yield of wheat leaves at CK1 (300 kg hm-2), A1 (255 kg hm-2), B1 (210 kg hm-2), and CK2 (0 kg hm-2) levels, in order to investigate the effects of N application on the activities of key photosynthetic enzymes, gas exchange parameters, chlorophyll fluorescence parameters, dry matter accumulation distribution, yield, and NUE of wheat leaves. The results showed that the photosynthetic key enzyme activity, gas exchange parameters, chlorophyll fluorescence parameters, aboveground dry matter accumulation (SDM), reproductive organ dry matter accumulation (SPDM), and yield all had an increasing trend followed by a decreasing trend with increasing N application. There were high RuBPC activity, PEPC enzyme activity, net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), maximum photochemical efficiency (Fv/Fm), actual photochemical efficiency (ΦPSII), SDM, SPDM, yield and NUE in A1 treatment, which were 6.10%-30.45% higher than the rest of the treatments and 10.51%-64.95%, 7.05%-64.95%, 7.49%-26.66%, 11.61%-63.44%, 5.72%-49.85%, 1.68%-28.55%, 5.00%-46.01%, 18.95%-96.45%, 22.95%-177.44%, 4.15%-46.88%, 6.30%-25.42%, and intercellular CO2 concentration (Ci) was reduced by 11.73%-20.95% compared to the rest of the treatments. Correlation analysis revealed that the yield, dry matter accumulation, NUE and Pn, Gs, Tr, ФPSII were highly significantly positively correlated and highly significantly negatively correlated with Ci. The reciprocal effects of N application and variety intercropping reached significant levels for RuBPC enzyme activity at anthesis stage, PEPC enzyme activity from anthesis to milking, Fv/Fm and ΦPSII at nodulation and anthesis. Therefore, the moderate N reduction (255 kg hm-2) under the drip irrigation pattern in Xinjiang improved the photosynthetic performance of wheat and facilitated the distribution and transport of photosynthetic products to reproductive organs on the basis of increased dry matter accumulation, which was beneficial to yield formation.

      Physiological and transcriptional regulation mechanisms of nitrogen alleviating drought stress in peanut
      DING Hong, ZHANG Zhi-Meng, XU Yang, ZHANG Guan-Chu, GUO Qing, QIN Fei-Fei, DAI Liang-Xiang
      Acta Agronomica Sinica. 2023, 49(1):  225-238.  doi:10.3724/SP.J.1006.2023.24020
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      Nitrogen application has an important effect on plant growth and development under drought stress. The aim of this study is to clarify the physiological and transcriptional regulation mechanism of nitrogen for improving drought resistance in peanut. The physiological indexes and root transcriptome of peanut under nitrogen application, drought stress and drought and nitrogen application simultaneously exist treatments were determined. The results showed that the drought and nitrogen application simultaneously exist treatment increased peanut biomass and the relative water content of leaves under drought stress. The content of total phenols and flavonoids in peanut roots were increased by nitrogen application under drought stress. Meanwhile, the activities of POD and CAT were increased, the content of MDA was decreased, which improved the drought resistance of peanut. Transcriptome analysis showed that the relative expression of 5396 genes changed due to nitrogen application. These genes were mainly involved in glutathione metabolism, nitrogen metabolism, and carbon metabolism, as well as stress and defense responses. Under drought stress, the drought and nitrogen application simultaneously exist treatments, the differentially expressed genes of secondary metabolite biosynthesis, transportation and catabolism and carbohydrate transport and metabolism were enriched. Among the three pathways related to phenolic metabolites, 51 differential genes were up-regulated and 207 genes were down-regulated under the drought and nitrogen application simultaneously exist treatment. In conclusion, the application of nitrogen fertilizer could enhance the antioxidant capacity of peanut plants under drought stress through regulating secondary metabolites and carbohydrate metabolism, and thus improve the drought resistance of peanut.

      Effects of calcium application on the distribution of photosynthetic carbon in plant-soil system at different peanut pod development stages
      ZOU Xiao-Xia, LIN Yi-Min, ZHAO Ya-Fei, LIU Yan, LIU Juan, WANG Yue-Fu, WANG Wei- Hua
      Acta Agronomica Sinica. 2023, 49(1):  239-248.  doi:10.3724/SP.J.1006.2023.24009
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      Investigating the effects of calcium application on the distribution of photosynthetic carbon in the plant-soil system at different stages of the development of peanut pods will help improve the management of calcium fertilizer, and increase the yield of peanut, and the concentration of soil organic carbon. In this study, the common large peanut variety ‘Huayu 22’ was selected, and four gradients of calcium were applied. They included CaO 0 kg hm-2, 75 kg hm-2, 150 kg hm-2, and 300 kg hm-2, and were designated T0, T1, T2, and T3, respectively. These treatments were established to explore the effects of calcium application on peanut yield and the distribution of photosynthetic carbon in the plant-soil system at different stages of peanut pod development. The results showed that the total dry matter accumulation of peanut plants was not affected by the application of different amounts of calcium. The application of a suitable amount of calcium significantly reduced the number of peanut fruit and kernel per kilogram, increased the kernel percent, full pod percent and pod yield, and in 2018 and 2019, the T2 treatment increased the pod yield by 17.5% and 25.1% compared with T0, respectively. A fitting analysis of the calcium applied with the peanut pod and kernel yield revealed that the highest peanut pod and kernel yield could be obtained when the calcium applications were 165 kg hm-2 and 173 kg hm-2, respectively. The application of a suitable amount of calcium significantly increased the photosynthetic 13C accumu-lation in peanut plants at the young fruit and pod bulking stages, increased the proportion of 13C in peanut kernels at different pod development and the pod setting and kernel filling stages. The proportion of 13C in the peanut kernels under the T2 and T3 treatments was 33.4%-37.2% and 38.7%-40.0%, respectively. The proportion of 13C in the soil also increased when a suitable amount of calcium was applied. The increase was as high as 52.6% (T2), but with the development in peanut pods, the proportion of 13C in soil decreased gradually. In conclusion, the application of an appropriate amount of calcium can regulate the distribution of photosynthetic 13C in the plant-soil system at different pod development stages of peanut and significantly improved the peanut yield and proportion of photosynthetic 13C in peanut kernel and soil. Under the conditions of this study, the recommended amount of calcium to apply was 173 kg hm-2.

      Effects of arbuscular mycorrhizae fungi on maize physiological characteristics during grain filling stage, yield, and grain quality under different nitrogen fertilizer forms
      CHEN Bing-Jie, ZHANG Fu-Liang, YANG Shuo, LI Xiao-Li, HE Tang-Qing, ZHANG Chen-Xi, TIAN Ming-Hui, WU Mei, HAO Xiao-Feng, ZHANG Xue-Lin
      Acta Agronomica Sinica. 2023, 49(1):  249-261.  doi:10.3724/SP.J.1006.2023.23010
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      Clarifying the effect of arbuscular mycorrhizae fungi (AMF) on maize physiological characteristics and grain yield and their quality at grain filling stages could provide a theoretical basis for the reasonable application of biological fertilizer in farmland, which can increase maize yield and improve grain quality. In maize growing season of 2018 and 2019, the two-factors pot experiments were carried out by compartment box devices. The factors were nitrogen (N) fertilizer forms (NH4+-N: ammonium nitrogen fertilizer; NO3--N: nitrate nitrogen fertilizer), and arbuscular mycorrhizal fungi (M0: neither root nor arbuscular mycorrhizal fungi could enter the hyphal chamber from the growth chamber; M1: only arbuscular mycorrhizal fungi could enter the hyphal chamber from the growth chamber). The key enzymes activities of N metabolism in grains and ear leaves, grain yield, plant biomass, plant N accumulation, and root characteristic parameters were measured. The results showed that AMF could increase leaf chlorophyll content and leaf area, promote photosynthesis, and regulate the key enzymes activities of N metabolism at grain filling stage, thus improving maize yield and quality. This effect was different between N fertilizer forms. Compared with M0, maize yield and grain N accumulation of M1 for NH4+-N fertilizer treatment increased by 85% and 140%, respectively. For NO3--N treatment, maize yield and grain N accumulation of M1 increased by 36% and 81%, respectively. Compared with M0, crude protein content, crude starch content, and lysine content of M1 for NH4+-N fertilizer treatment increased by 9%, 6%, and 7%, while crude fat content reduced by 19%, respectively. For NO3--N treatment, crude protein content and lysine content of M1 increased by 10% and 8%, while crude fat content reduced by 32%, respectively. In conclusion, AMF could improve maize yield, increase crude protein content, and lysine content in maize grain, thus improving maize grain quality.

      Tuber sugar-end adaptability, stability, and screening of French fries processing varieties in potato
      DUAN Hui-Min, WANG Yu, CHENG Li-Xiang, SA Gang, XIA Lu-Lu, ZHANG Feng
      Acta Agronomica Sinica. 2023, 49(1):  262-276.  doi:10.3724/SP.J.1006.2023.24024
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      French fries need to have a bright and uniform color in the process of potato processing. Potato tuber sugar-end would make the fried fries brown ends. Screening the French fries processing varieties with sugar-end resistance by analyzing component content and color parameters related to sugar-end in the tuber and combining the genotype + genotype and environment interactions (GGE) model would provide a theoretical basis for the selection and planting of French fries processing varieties. Eight varieties (lines) with excellent comprehensive agronomic traits were selected and planted in two different ecological areas of Hexi irrigation area (Yongchang) and Alpine humid area (Weiyuan). After harvest, the tubers were stored at room temperature (20℃) and low temperature (4℃), respectively. Then, the contents of starch, fructose, glucose, sucrose, and free amino acids at the basal and apical tubers were measured after 15 days and 60 days storage. The color of basal and apical ends of French fries was measured for evaluating tuber sugar-end type. Meanwhile, the effects of locations, varieties, storage conditions, and their interactions on tuber sugar-end were analyzed. Combining with the GGE model, the adaptability and stability of the tested varieties showed that six varieties had tuber sugar-end in Yongchang, among which five varieties were basal sugar-end and one variety was apical sugar-end. In Weiyuan, nine varieties had tuber sugar-end, among which four varieties were basal sugar-end and five varieties were apical sugar-end. The low color difference at the basal and apical ends of potato varieties indicated that the sugar-end degree was low in Yongchang location. The variance analysis indicated that the environment and interaction effects were the primary factors that determined tuber sugar-end. Among the interaction effects, the interaction between environment and genotype played a role in determining sugar-end. The GGE model revealed that the composition of basal ends was higher adaptability than the apical end of tubers. Moreover, the sucrose and free amino acids of tubers were higher stability than starch and reducing sugar in each location. The suitable location for planting fries processing potatoes was Yongchang, and more accurately discriminability location for the tuber sugar-end was Weiyuan. The sugar-end varieties can be better identified under room temperature storage. In conclusion, H0940 was a material with sugar-end resistance and Gannongshu 7 was a processing variety with sugar-end resistance.

      RESEARCH NOTES
      Effects of foliar spraying of urea post anthesis on nitrogen uptake and utilization and yield in winter wheat
      CHEN Jia-Jun, LIN Xiang, GU Shu-Bo, WANG Wei-Yan, ZHANG Bao-Jun, ZHU Jun-Ke, WANG Dong
      Acta Agronomica Sinica. 2023, 49(1):  277-285.  doi:10.3724/SP.J.1006.2023.11116
      Abstract ( 407 )   HTML ( 12 )   PDF (715KB) ( 317 )   Save
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      Foliar spraying of nitrogen fertilizer can delay senescence and increase yield of wheat post anthesis, but few studies of its effect on nitrogen use efficiency of wheat is known. In this study, Jimai 229, a strong gluten winter wheat variety, was used as experimental material, and a two-factor random block design was used to set two periods of urea spraying on leaves, namely 7 d (S) and 21 d (T) post anthesis. Setting 4 urea solution concentrations (0, 2%, 6%, and 10%) was to explore the effects of foliar urea spraying post anthesis on nitrogen absorption and accumulation, grain yield, and nitrogen use efficiency in winter wheat. The results showed that grain yield of wheat increased first and then decreased with the increase of spraying urea solution concentration, and reached the highest at 2% concentration (5.1% higher than the control), mainly due to the increase of 1000-grain weight (3.3% higher than the control). Spraying 2% urea solution at different times post anthesis promoted the redistribution of pre-flowering storage nitrogen to grains, and increased the amount of post-flowering assimilation nitrogen to grains by 8.8% and 21.1%, respectively. Grain nitrogen accumulation per unit area and nitrogen harvest index increased by 10.9% and 7.9%, respectively, resulting in significantly increasing the grain nitrogen content, protein content, and nitrogen use efficiency. When 2% urea solution was applied foliar spraying, and the spraying time was delayed from 7 days post anthesis to 21 days post anthesis, the increase of grain nitrogen accumulation, grain yield and nitrogen use efficiency was greater. In conclusion, spraying 2% urea solution on leaves post anthesis can promote the absorption of nitrogen and the redistribution of temporary storage nitrogen in vegetative organs to grains post anthesis, thus significantly improving grain protein content and yield, grain yield, and nitrogen use efficiency. Grain protein content and yield, grain yield and nitrogen use efficiency were increased more by spraying at the middle and late filling stages than at the early filling stage.

      Effects of shading postanthesis on flag leaf chlorophyll content, leaf microstructure and yield of different wheat varieties
      LI Xiu, LI Liu-Long, LI Mu-Rong, YIN Li-Jun, WANG Xiao-Yan
      Acta Agronomica Sinica. 2023, 49(1):  286-294.  doi:10.3724/SP.J.1006.2023.11118
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      Low light from flowering to maturity is one of the environmental stresses in wheat production. In this study, four commercial varieties, Zhengmai 9023, Xiangmai 55, Yangmai 158, and Fumai 1228 from Jianghan Plain, were used to investigate the influence of low light on wheat yield and the mechanisms of plants’ adaptation to low light. Shading (AS) treatments were started from flowering till maturity with normal light treatment as the control (CK). Traits monitored from flowering to maturity included chlorophyll contents, chlorophyll a/b and leaf microstructure in flag leaves, and low-light tolerance indicators of superoxide dismutase enzyme activity, dry matter, and yield. Results showed that compared with controls, shading postanthesis resulted in increasing SPAD value of flag leaf, superoxide dismutase (SOD) activity, chlorophyll a and chlorophyll b contents, decreased palisade tissue thickness of spongy tissue, tightness of leaf tissue structure, dry matter accumulation, and grain yield of all varieties. Varieties revealed different responses to low light treatment with the morphology and distribution of mesophyll cells of the flag leaf of Xiangmai 55 and Yangmai 158 being less affected than Zhengmai 9023 and Fumai 1228. Compared with Zhengmai 9023 and Fumai 1228, the SPAD value, chlorophyll a content, chlorophyll b contents, and superoxide dismutase activity of flag leaves of Xiangmai 55 and Yangmai 158 increased significantly, while the chlorophyll a/b decreased significantly. Shading treatment caused yield reductions were much less in Xiangmai 55 (29%) and Yangmai 158 (34%) than Zhengmai 9023 (38%) and Fumai 1228 (47%), indicating that Xiangmai 55 and Yangmai 158 were capable of maintaining high productivity resulted in a high level of adaptability to low-light environments. The ability to maintain a higher physiological activity of flag leaf was the major physiological mechnism for higher productivity of wheat under insufficient light conditions.

Co-sponsored:
the Crop Science Society of China
the Institute of Crop Science, CAAS
China Science Publishing & Media Ltd.
Published: Science Press
Editor-in-chief: Wan Jian-min
Associate Editors-in-Chief:
Chen Xiao-ya Yang Jian-chang Zhang Xian-long Wang Jian-kang Xu Ming-liang Liu Chun-ming Wang Dao-wen Sun Chuan-qing Ding Yan-feng Jin Wei-wei Chu Cheng-cai Cheng Wei-hong
Director of the editorial department:
Yan Chun-ling
CN 11-1809/S
ISSN 0496-3490
Post subscription code: 82-336

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  • Started in 2013
  • Covered by SCIE
  • Open access in ScienceDirect

Editor in chief: Wan Jian-min
CN 10-1112/S
ISSN 2095-5421, 2214-5141(online)
Online published:
https://www.sciencedirect.com/journal/the-crop-journal
Submission: https://www.editorialmanager.com/cj/
E-mail: cropjournal@caas.cn
Tel: 8610-82108548

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