Table of Content

12 September 2019, Volume 45 Issue 9

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REVIEW

Mechanisms underlying plant resistance to the acetohydroxyacid synthase- inhibiting herbicides

XU Qian-Yu,LAN Yu,LIU Jia-Xin,ZHOU Xin-Yu,ZHANG Gang,ZHENG Zhi-Fu

Acta Agronomica Sinica. 2019, 45(9):  1295-1302.  doi:10.3724/SP.J.1006.2019.93003

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The acetohydroxyacid synthase (AHAS)-inhibiting herbicides have been widely used in agricultural industry. However, the herbicides can sometimes cause phytotoxicity for those crops susceptible to them. Thus, it is important to create a series of new crop varieties resistant to different types of herbicides. This review presents our current understanding about the categories and characteristics of the AHAS-inhibiting herbicides, the properties of their respective target enzymes and their roles in the synthesis of branched chain amino acids, and the mechanisms underlying two types of plant resistance to the herbicides (namely, target- and non-target-site-based resistance), as well as our perspectives on the future trends in these research areas, which is expected to promote the research and development of herbicide-resistant crops.

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Genome-wide association study of silique length in rapeseed (Brassica napus L.)

SUN Cheng-Ming,CHEN Song,PENG Qi,ZHANG Wei,YI Bin,ZHANG Jie-Fu,FU Ting-Dong

Acta Agronomica Sinica. 2019, 45(9):  1303-1310.  doi:10.3724/SP.J.1006.2019.94021

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Silique length is a key agronomic trait of rapeseed. Moderately increasing silique length is conducive to high seed yield by enlarging photosynthetic area and seed volume. A collection of 496 representative rapeseed accessions was genotyped by the Illumina 60K SNP array, and phenotyped for silique length in four environments. The genome-wide association study (GWAS) of silique length was performed via the MLM (Mixed linear model) and GLM (General linear model). Seven loci and 25 loci were detected with MLM and GLM, which explained 25.01% and 41.77% of the phenotypic variance, respectively. Combining the common loci between two models, we finally got 27 unique loci, of which seven were overlapped with reported QTLs, and 20 were new one. Bn-A09-p29991443, the most effective locus, was located on chromosome A09, accounting for 13.89% and 12.86% of the phenotypic variance in MLM and GLM, respectively. Silique length of accessions with the favorable allele of Bn-A09-p29991443 was averagely 0.89 cm longer than that with the unfavorable allele. The cloned silique length genes ARF18 and BnaA9.CYP78A9 in rapeseed was found to be colocalized with Bn-A09-p29991443. Besides, five candidates including GID1b, FUL, EOD3, DOF4.4 and GA20ox1, orthologous to documented Arabidopsis silique length genes, were found near our GWAS loci. The results provide an insight into the genetic basis of silique length and lay a foundation for further mechanism exploration and breeding for this trait in B. napus.

Function analysis of 5′ untranslated region introns in drought-resistance gene TaSAP1

CHANG Jian-Zhong,DONG Chun-Lin,ZHANG Zheng,QIAO Lin-Yi,YANG Rui,JIANG Dan,ZHANG Yan-Qin,YANG Li-Li,WU Jia-Jie,JING Rui-Lian

Acta Agronomica Sinica. 2019, 45(9):  1311-1318.  doi:10.3724/SP.J.1006.2019.81053

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Stress associated proteins (SAPs), a group of A20/AN1 zinc-finger domain-containing proteins, are mainly involved in responding to abiotic stresses in plant. TaSAP1 involved in the responses of wheat to several abiotic stresses has two introns in the 5' untranslated region intron (5UIs). In this study, the two 5UIs were removed respectively by using overlapping PCR, and the expression vectors were constructed and transformed into Brachypodium distachyon via Agrobacterium-mediated transformation. The functions of TaSAP1 promoter and 5UIs were analyzed according to GUS activity. The activity of TaSAP1 promoter (P1) was up-regulated under the stresses of drought, cold and exogenous abscisic acid (ABA) by 10, 6, and 4 folds, respectively. The 5UIs were absolutely necessary for the promoter activity that lost in the double mutants of 5UIs. Intron-1 deletion led to 2.7-fold decrease (P<0.05) in GUS activity, whereas Intron-2 deletion resulted in that P1 was not able to respond to drought, low temperature and exogenous abscisic acid. These results provide basic information for further study in biological function of TaSAP1 5UIs.

Genetic dissection of combining ability and heterosis of rice agronomic traits based on pathway analysis

XIANG Li-Yuan,XU Kai,SU Jing,WU Chao,YUAN Xiong,ZHENG Xing-Fei,DIAO Ying,HU Zhong-Li,LI Lan-Zhi

Acta Agronomica Sinica. 2019, 45(9):  1319-1326.  doi:10.3724/SP.J.1006.2019.82062

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In order to provide theoretical foundation of cultivating and improving rice, under North Carolina design II, we constructed test cross population and conducted pathway analysis of phenotype performance, combining ability and heterosis of agronomic trait in present study. The experiments’ results reveal that the filled grains per panicle, 1000-grain weight, main panicle length, primary/secondary branch of main panicle, plant height, spikelet per panicle, tillers per plant, and yield per plant were separately related to pathway of biological regulation, cysteine and methionine metabolism, snare interactions in vesicular transport, DNA-dependent transcription, macromolecular metabolism, recognition of pollen, hydrolase activity, purine nucleoside binding and so on. Therefore, in order to obtain elite hybrids with high combining ability and heterosis, it is feasible to start from studying related pathways of a certain trait and related genes regulating the pathway.

Expression of OsUBA and its function in promoting seed germination and flowering

ZHANG Shuang-Shuang,WANG Li-Wei,YAO Nan,GUO Guang-Yan,XIA Yu-Feng,BI Cai-Li

Acta Agronomica Sinica. 2019, 45(9):  1327-1337.  doi:10.3724/SP.J.1006.2019.82069

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Autophagy is a cellular process by which dysfunctional or unnecessary cellular components are degraded. Autophagy plays important roles in growth and development, and makes responses to nutritional deficiency and biotic/abiotic stress responsiveness in eukaryotes. NBR1 (Next to BRCA1 gene 1, NBR1) proteins were the most important autophagy cargo receptors found in plants. Up to date, only limited reports about NBR1 were available in plants, and the function of NBR1 proteins in rice remains unclear. An UBA (Ubiquitin associated, UBA) domain-containing gene was cloned from cDNA of rice (Oryza sativa L. japonica cv. Nipponbare) seedlings and was named as OsUBA. The open reading frame of OsUBA is 2538 bp in length and encodes 845 amino acids residues. Conserved domain prediction and phylogenetic analysis suggested that OsUBA belongs to NBR1 proteins. Promoter analysis suggested that many motifs related to light-, stress-, and hormone responsiveness were predicted in OsUBA promoter sequence. Gus staining of the rice plants harboring OsUBA p:Gus showed that OsUBA was highly expressed in anthers, germinating seeds, and roots, OsUBA transcripts could also be detected in stems and leaves. Expression of OsUBA was dramatically inhibited by 200 μmol L ^-1 ABA treatment, and slightly increased by 100 μmol L ^-1 GA treatment. Compared with the wild type control, the OsUBA-overexpressors germinated more quickly and flowered obviously earlier. The seed germination of the OsUBA-overexpressed rice lines was obviously inhibited by 3 μmol L ^-1 ABA treatment, and promoted slightly by 100 μmol L ^-1GA treatment. These results suggested that the expression and function of OsUBA may be related to regulations of flowering time, seed germination and biotic/abiotic stress responsiveness in rice.

QTL mapping of oleic acid, linoleic acid and linolenic acid contents in Brassica napus L. using DH and IF₂ populations

MENG Jiang-Yu,FU Ying,HE Ya-Jun,QIAN Wei

Acta Agronomica Sinica. 2019, 45(9):  1338-1348.  doi:10.3724/SP.J.1006.2019.84172

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DH and IF₂ populations, consisting of 261 and 234 lines respectively, constructed using the German winter rapeseed cultivar ‘Express’ (female) and the Chinese semi-winter line ‘SWU07’ (male), were used to detect QTLs related to oleic acid, linoleic acid and linolenic acid contents in different years. A total of 71 QTLs were detected in DH population in four-year environment and 4 QTLs in IF₂ population in two-year environment. After eliminating the overlapped QTLs detected in different years or different populations, totally 51 QTLs for the three traits were obtained, 15 QTLs of which were persistently detected in more than two years. These 51 QTLs were located on 13 linkage groups. Among them, 18 QTLs related to oleic acid content were located on A01, A02, A04, A05, A07, A09, and C01, respectively, explaining phenotypic variation ranging from 3.44% to 13.97%, 12 QTLs related to linoleic acid content were located on A02, A06, A09, C01, and C02, respectively, explaining phenotypic variation ranging from 3.84% to 19.51%, and 21 QTLs related to linolenic acid content were located on A01, A02, A03, A04, A05, A08, A09, C01, C02, C03, and C06, respectively, explaining phenotypic variation from 2.86% to 11.91%. These results provide more genetic information for the improvement of fatty acid quality in rapeseed breeding.

Identification of rice stress-related gene co-expression modules by WGCNA

LI Xu-Kai,LI Ren-Jian,ZHANG Bao-Jun

Acta Agronomica Sinica. 2019, 45(9):  1349-1364.  doi:10.3724/SP.J.1006.2019.82061

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Weighted Gene Co-expression Network Analysis (WGCNA) is a systematic biological method describing gene association patterns among different samples. It can be used to identify synergistically altered gene sets. In this study, 47 transcriptome data of rice tissues specimens were used to explore the regulation relationship between genes under harsh environmental conditions (cold, drought, and salt) try WGCNA method. By filtering the low expressed genes, the co-expression matrix was finally constructed using the screened 30,339 expressed genes. Subsequently, 15 modules were obtained. The reports of cloned key genes under those three stresses existed in each module, so the GO enrichment analysis was performed on the predicted target genes. The differentially expressed genes were analyzed by transcriptome data under harsh conditions, and combined with the reported stress-related genes, two stress-related modules were selected to construct the gene regulatory network. In consideration of a large number of genes related to the mentioned harsh situations in the green module, the GO functional enrichment analysis was carried out for the three kinds of stress genes under the green module, and the gene regulatory network was constructed for the common genes. In summary, 2599 harsh environmental situations-related genes were mined. Meanwhile, 25 key genes related to stress resistance were predicted. Our results on stress resistance and comprehensive stress resistance open a new window for future studies.

Genome-wide characterization and transcriptional analysis of the protein disulfide isomerase-like genes in barley (Hordeum vulgare)

SHI Li-Jie,JIANG Cong-Cong,WANG Fang-Mei,YANG Ping,FENG Zong-Yun

Acta Agronomica Sinica. 2019, 45(9):  1365-1374.  doi:10.3724/SP.J.1006.2019.81087

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Protein disulfide isomerase (PDI) and PDI-like proteins (PDILs) belong to a protein family that are usually located on endoplasmic reticulum and highly conserved across eukaryotes. The main function of PDILs is catalyzing the redox and isomerization of disulfide bonds in protein precursors via the thioredoxin (TRX) domain. PDILs have been also reported as chaperones in folding and unfolding of proteins, thus being important in growth and development, as well as biotic or abiotic stress responses of plant. In this study, we identified by bioinformatics analysis 10 members of barley PDILs (HvPDILs), which were subjected for analyzing the physical location, protein structure and subcellular localization. The phylogenetic analysis revealed eight sub-branches of plant PDILs, and barley PDILs showed a high sequence homology with wheat PDILs. The transcriptional analysis revealed large variation of the transcription abundance of PDILs in different tissues and development stages. Notably, mechanical inoculation of Barley mild mosaic virus (BaMMV) resulted in transcriptional re-programming of several HvPDILs. This result suggests the association between PDILs and BaMMV infection, despite that the functional mechanism remains largely unknown and needs further studies.

TILLAGE & CULTIVATION· PHYSIOLOGY & BIOCHEMISTRY

Plant type and canopy light interception characteristics in double cropping rice canopy under different nitrogen rates

LI Yan-Da,HUANG Jun-Bao,YE Chun,SHU Shi-Fu,SUN Bin-Feng,CHEN Li-Cai,WANG Kang-Jun,CAO Zhong-Sheng

Acta Agronomica Sinica. 2019, 45(9):  1375-1385.  doi:10.3724/SP.J.1006.2019.92005

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The interception of photosynthetically active radiation (PAR) within canopy direct affects double cropping rice photosynthesis and yield formation. The objective of this study was to elucidate the spatial and temporal distribution characteristics of plant type and canopy interception of PAR in double cropping rice under different development stages, cultivar types and nitrogen rates. Field experiments were conducted using four early and late rice cultivars with four nitrogen application rates at Jiangxi in 2016 and 2017. The plant morphology and canopy interception rate of PAR (IPAR) in different canopy heights at different development stages were measured. The nitrogen application rate had significant effects on the plant height, ear length, leaf length and basic leaf angle. All of them increased with increasing nitrogen application rate. The layer leaf area index (LAI) and upward accumulated LAI of early and late rice were greater at booting stage than at 12 d after heading. The layer LAI was greater in mid canopy than in upper and basal canopy. The maximum layer LAI appeared at 0.58 of relative canopy height. The layer LAI and upward accumulated LAI in upper and mid canopy of early and late rice increased with increasing nitrogen application rate. The distribution of upward accumulated LAI followed sigmoid curve with relative height, which could be quantitatively described with Logistic equation (R ² > 0.99). The canopy IPAR of early and late rice was greater at booting stage than at 12 d after heading, and increased with increasing nitrogen application rate. The diurnal variation of IPAR was smaller at noon than in the morning and afternoon. Lower canopy IPAR was observed for the compact plant type of early and late rice cultivars. The relationship between canopy IPAR and downward accumulated LAI could be quantitatively described with an equation of IPAR = a (1-e ^{- b ×LAI}) (R ²> 0.88). IPAR on horizontal plane of the three-dimensional distribution was smaller, with a greater variation of light flecks in upper and mid canopy than in basal canopy. The IPAR at the same canopy height was non-uniform on the horizontal plane. These results would provide a support on cultivation for high yield and optimal design of plant type in double cropping rice.

Effects and physiological mechanisms of sowing depth on the growth progress and leaf senescence of peanut

ZHEN Xiao-Yu,YANG Jian-Qun,LI Xin-Xin,LIU Zhao-Xin,GAO Fang,ZHAO Ji-Hao,LI Ying,QIAN Bi-Chang,LI Jin-Rong,YANG Dong-Qing,LI Xiang-Dong

Acta Agronomica Sinica. 2019, 45(9):  1386-1397.  doi:10.3724/SP.J.1006.2019.94074

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A 2-year field study was conducted using Shanhua 108 with seven levels of sowing depth (SD3, SD5, SD7, SD9, SD11, SD13, and SD15) by ridging and mulching under the suitable soil moisture condition to identify and assess the effects of sowing depth on growth progress, chlorophyll content, photosynthetic characteristics, dry matter accumulation, antioxidant enzyme activities and yield formation in peanut. The sowing depth significantly affected the emergence time of peanut. Compared with SD5 treatment, the seedling emergence time of SD15 was delayed five days (d), and the yield formation period was shortened 2.5 d. The shallow seeding treatment (SD3) and deep-planting treatments (depth ＞7 cm) significantly reduced the height of main stem and the length of branch, resulting in a decrease in leaf area index (LAI). Moreover, the chlorophyll content and net photosynthetic rate during yield formation period of those treatments were significantly decreased, leading to a decrease of dry matter accumulation of plants. At the same time, increasing sowing depth significantly reduced soluble protein content, superoxide dismutase (SOD) and peroxidase (POD) activities, increased malonaldehyde (MDA) content during the yield formation period. The pod yield and seed yield in SD5 treatment was the highest due to the highest pod number per plant, the single pod weight and shelling rate, and deep-sowing (depth >7 cm) was adverse to yield. Therefore, the appropriate sowing depth should be 5 cm in the peanut cultivation practice.

Effect of above- and below-ground interaction intensity on photosynthetic characteristics of wheat-maize intercropping

DU Jin-Yong,CHAI Qiang,WANG Yi-Fan,FAN Hong,HU Fa-Long,YIN Wen,LI Deng-Ye

Acta Agronomica Sinica. 2019, 45(9):  1398-1406.  doi:10.3724/SP.J.1006.2019.81093

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A field experiment of wheat-maize intercropping was conducted from 2015 to 2017, with three root separation treatment adopted to produce the different below-ground interactions: (i) root separation with producing plastic cloth no below-ground interaction (P); (ii) root separation with producing nylon mesh partial below-ground interaction (N); and (iii) no root separation, producing complete below-ground interaction. Two planting densities; M1 and M2 (with 45,000 and 52,500 maize plants per hectare), were employed to create the different above-ground interactions. The above- and below-ground complete interaction significantly improved the leaf area duration (LAD), net assimilation rate (NAR) of the intercropped, and net photosynthetic rate (P_n) of the intercropped maize. Compared with low density treatment, the LAD of high maize density was improved by an average of 12.4%. Compared with nylon mesh and plastic sheet root barriers no root barrier increased LAD by 10.3% and 29.0%. Maize P_n was improved by 11.2% under high density than under low density. No root barrier improved P_n by 4.7% and 7.7% as compared with nylon mesh and plastic sheet root barriers, respectively. There was no significant effect of maize density on NAR of the intercropping system. No root barrier improved NAR by 11.5% and 14.8% as compared with nylon mesh and plastic sheet root barriers, respectively. During the late growth period, grain yield was significantly correlated with LAD. The above- and below-ground interactions synergistically affected LAD and P_n, which influenced NAR of the intercropping system. Therefore, the synergistic effect could be promoted by increasing maize density and above- and below-ground interactions, which would promote the intercropping system productivity.

Spatial and temporal patterns of drought risk for winter wheat grown in Hebei province in past 60 years

ZHANG Li,CHEN Fu,LEI Yong-Deng

Acta Agronomica Sinica. 2019, 45(9):  1407-1415.  doi:10.3724/SP.J.1006.2019.81074

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Drought is a major natural disaster that causes crop yield losses. Study on the cause mechanism and spatio-temporal patterns of drought is of great significance for regional food security. Based on long-term climate data during 1958-2016, we analyzed the spatial and temporal patterns of drought risk of winter wheat in Hebei province in the past 60 years by calculating Crop Water Deficit Index (CWDI). The water requirement and drought risk during the growth period of winter wheat increased at first, then decreased and then increased. Drought risk was the highest in jointing-heading stage, followed by heading-maturity stage. Winter wheat suffered severe drought during the whole growing periods, particularly in the middle and late stages of yield formation. The Hei-long-gang region in southeastern Hebei faced an extreme high drought risk. Drought risk of winter wheat was affected by various factors such as precipitation, temperature, humidity. The most important impact factor was precipitation, and temperature was the key factor affecting the CWDI of winter wheat in the later stage. With climate changed in recent decades, the temperature during crop growth season showed a clear upward trend, increasing the water consumption of winter wheat. The results of this study reveal the spatio-temporal patterns of drought risk of winter wheat, identify high drought risk areas and key growth stages, and provide a reference for regional water irrigation management and drought disaster mitigation in a changing climate.

Screening and comprehensive evaluation of aluminum-toxicity tolerance during seed germination in Brassca napus

GAO Huan-Huan,YE Sang,WANG Qian,WANG Liu-Yan,WANG Rui-Li,CHEN Liu-Yi,TANG Zhang-Lin,LI Jia-Na,ZHOU Qing-Yuan,CUI Cui

Acta Agronomica Sinica. 2019, 45(9):  1416-1430.  doi:10.3724/SP.J.1006.2019.84169

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Seed germination is an important stage of plant morphogenesis in rapeseed. Aluminum toxicity is one of the main factors affecting seed germination in acidic soil. Therefore, it is important for rapeseed production and research to screen Al-tolerant germplasms during seed germination. In this study, five Brassica napus cultivars (lines) were used to screen the optimum treatment concentration of Al toxicity at germination stage, which was determined at 90 μg mL ^-1. The germination vigor, germination rate, fresh weight, dry weight, root length and bud length of 148 cultivars (lines) of Brassica napus were measured at germination stage. The comprehensive evaluation value (A value), average subordinate function value (ASF value), weighted tolerance coefficient (WAC value), correlation coefficient, frequency, principal component, grey relational degree, clustering and stepwise regression were used to identify the Al tolerance at germination stage. A comprehensive evaluation model of Al tolerance at germination stage was established, suitable evaluation and identification indexes were selected. There were significant differences in the germination parameters of 148 Brassica napus germplasm, and aluminum-tolerant Brassica napus varieties (lines) during germination stage were screened, including 01188, WH-20, A109, and Jiayu 31 peng. The results of grey correlation and regression analysis indicated that the root length, bud length, fresh weight, germination rate and germination potential measured at the germination stage of rapeseed, and the A value of the indices estimated by regression equation, could be preliminarily judged the aluminum tolerance of rape germplasm.

RESEARCH NOTES

Effects of salt stress on physiological indexes and differential proteomics of oat leaf

CHEN Xiao-Jing,LIU Jing-Hui,YANG Yan-Ming,ZHAO Zhou,XU Zhong-Shan,HAI Xia,HAN Yu-Ting

Acta Agronomica Sinica. 2019, 45(9):  1431-1439.  doi:10.3724/SP.J.1006.2019.81088

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MDA content, SOD and POD activities, free proline content of oat leaves were determined under salt stress (molar NaCl: Na₂SO₄=1:1), and the differentially expressed proteins in leaves were analyzed by using Label-Free technique. The results showed that the activities of MDA, SOD and POD in oat leaves decreased by 16.7%, 23.4%, and 21.2% respectively, and free proline content increased by 1.12% compared with the control. There were 76 differential proteins with P-value ≤ 0.05 and ratio > 2 (51 proteins up-regulated and 25 proteins down-regulated). The GO annotation indicated that 27 differential proteins were significantly enriched in 16 metabolic pathways, of which the oxidation-reduction process was 33.9%. The biological processes of level 3 statistical enrichment were oxygen binding and oxidoreductase activity. Twenty-two differential proteins were obtained using KEGG annotation, which was significantly enriched in 10 biochemical metabolic pathways, mainly including four processes: protein processing in endoplasmic reticulum, longevity regulating pathway-multiple species, antigen processing and presentation, estrogen signaling pathway. The STRING protein interaction network showed that 10 of the 21 differential proteins involved in post-translational modification, protein turnover, and molecular chaperone function, and HSP70 and HSP90 interacted with the most core proteins of the whole network. It is speculated that the up-regulation of core protein is one of the reasons for the salt tolerance of oats.

Molecular identification and chromosomal mapping of exogenous Bt gene in two insect-resistant cotton varieties

ZHOU Xiang-Yang,ZHAO Liang,DI Jia-Chun,CHEN Xu-Sheng

Acta Agronomica Sinica. 2019, 45(9):  1440-1445.  doi:10.3724/SP.J.1006.2019.84167

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Molecular identification and chromosomal localization of Bt genes in two insect-resistant cotton varieties GK19 from China and 33B from the United States were conducted to explore the molecular basis of the differences between the two transgenic cotton varieties in perspective of exogenous gene transformation events. GK19 was a domestic Bt transgenic insect-resistant cotton variety, its Bt gene was located on cotton Chr.20, and linked to a total of 16 pairs of SSR polymorphic markers, flanking sides were markers NAU3907 and NAU2579 with genetic distance of 2.4 cM and 1.5 cM, respectively. The Bt gene in 33B was located on cotton Chr.26, with a total of 20 pairs of SSR polymorphic markers linking to the Bt gene, the target Bt gene was located between markers NAU460 and dc40260, with genetic distance of 3.6 cM and 2.0 cM, respectively. This study revealed that GK19 and 33B were from different transgenic events.

Grain filling, dehydration characteristics and changes of endogenous hormones of summer maize hybrids differing in maturities

WAN Ze-Hua,REN Bai-Zhao,ZHAO Bin,LIU Peng,ZHANG Ji-Wang

Acta Agronomica Sinica. 2019, 45(9):  1446-1453.  doi:10.3724/SP.J.1006.2019.83078

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This study was expected to explore the relation of grain-filling and dehydration characteristics with changes of endogenous hormones of summer maize hybrids differing in maturities, providing theoretical references for mechanized harvest of grains, high-yield, high-efficiency production and breeding of summer maize hybrids in the Huang-Huai-Hai Rivers region. The early maturity hybrids Denghai 518 (DH518), Hengzao 8 (HZ8) and the late maturity hybrids Zhengdan 958 (ZD958), Denghai 605 (DH605) were used to measure changes of dry matter accumulation, water content and endogenous hormone content in the process of kernel formation. Compared with the late maturity hybrids, the early maturity hybrids had shorter grain-filling duration, earlier beginning of dehydration, higher dehydration rate, lower kernel weight at physiological maturity stage, and lower yield. but among the early maturity hybrids, DH518 had significantly higher yield than HZ8. The endogenous hormones content and their changes in different hybrids were different, but the trend that the same hormone changed with grain development was the same. The ABA content of the early maturity hybrids in grain was higher than that of the late maturity hybrids, especially in the middle-late grain-filling stage. Both grain filling and dehydration rate were related to endogenous hormone, the dehydration rate of the early hybrids was positively correlated with ZR content.