Table of Content

12 July 2010, Volume 36 Issue 07

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Mapping Male Fertility Gene with SSR Markers in Parents of Cytoplasmic- Nuclear Male-Sterile Line NJCMS3A in Soybean

LI Shu-Guang,ZHAO Tuan-Jie,GAI Jun-Yi

Acta Agron Sin. 2010, 36(07):  1061-1066.  doi:10.3724/SP.J.1006.2010.01061

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Utilization of the three lines (cytoplasmic-nuclear male-sterile (CMS) line, maintainer line and restorer line) in producing hybrids with heterosis has been very successful in a number of crops including soybean. The soybean CMS line NJCMS3A was developed through six consecutive backcross generations with N21566 as cytoplasm source and N21249 as nuclear donor. The objective of our study was to reveal the genetic mechanism and mapping the male fertility gene in the two parents of the CMS line NJCMS3A, i.e. N21566 and N21249. The male fertility of (N21566×N21249) F₂ and BC₁F₁ showed that the segregation ratio of fertile to sterile plants fitted the expected ratios of 3:1 and 1:1, respectively, indicating one pair of gene conferring male fertility in the parents of NJCMS3A with dominance allele in N21249 being male fertile. This gene might be one of the restorer genes for the male sterility of NJCMS3A. The mapping results on BC₁F₁ and F₂ showed that out of the 793 randomly selected SSR markers, Satt331, CSSR133 and Satt477 on linkage group O were linked to the male fertility gene Rf with their genetic distances of 8.1~10.4 cM, 11.4~16.4 cM, 13.3~19.2 cM, respectively, in a same order and its location between Satt331 and Satt477.

Cloning and Sequence Analysis of KAPP Gene in Brassica oleracea

WU Wui-Ru,ZHU Li-Quan,LI Cheng-Qiong,YANG Ku,TANG Zhang-Liang,REN Xue-Song,WANG Xiao-Jia

Acta Agron Sin. 2010, 36(07):  1067-1074.  doi:10.3724/SP.J.1006.2010.01067

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The gDNA and cdna fragments of KAPP gene were amplified from genomic DNA, bud Rna and leaf Rna in Brassica oleracea by PCR and RT-PCR and other molecular biology methods. We initially obtained a fragment of KAPP gDNA with length of 3 247 bp, a fragment of KAPP cDNA with length of 1 699 bp, as well as a bud cdna with length of 1 578 bp and a leaf cdna with length of 1 581 bp which were called KAPP2 cDNA of bud and KAPP2 cDNA of leaf respectively. Compared gDNA with cDNA of KAPP, we found that there were 11 introns in KAPP gene, and these introns all followed typical GU-AG rule. Between KAPP cDNA which we cloned and KAPP cDNA released there are six nucleotide differences, but they encode a same amino acid sequence. Sequences analysis of the KAPP2 cDNA which we cloned from bud cdna and leaf cdna in Brassica oleracea showed that they share 85.2% and 85.0% identity with the reported KAPP cDNA respectively.We also found that the nonsense mutation in 590 bp of KAPP2 of bud cDNA and 593 bp of KAPP2 of leaf cDNA led to the early appearance of termination codon, who’s Blast indicated that both of them shared more identity in Arabidopsis thaliana than in Brassica oleracea. Based on KAPP cDNA sequence of eight species released by NCBI and two sequences of KAPP2 cDNA cloned in this study, we constructed a phylogenetic tree of KAPP gene, which showed that the two KAPP2 sequences were in the same group with released KAPP cDNA in Brassica oleracea. Based on all the above analysis, as well as some view of the comparative mapping research, we speculated that KAPP gene may have more than one copy in the genome of Brassica oleracea,the KAPP2 sequence cloned in this study may be the other copies of KAPP gene. Moreover, they are likely to be the pseudogene which was inactivated by mutation during evolution process. It has an important significance for the deep research between KAPP and Self-incompatibility. The results will provide some new insights into the research of molecular mechanism in SI and molecular evolution in Brassica oleracea.

Identification and Expression Analysis of ZmERD16,a Ubiquitin Extension Protein Gene in Maize (Zea mays L.)

LU Yue-Shang, LIU Ying-Hui, ZHANG Deng-Feng, SHI Yun-Su, SONG Yan-Chun, WANG Tian-Yu, YANG De-Guang, LI Yu

Acta Agron Sin. 2010, 36(07):  1075-1083.  doi:10.3724/SP.J.1006.2010.01075

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Ubiquitin extension protein is a fusion prot0ein of an ubiquitin monomer followed by a ribosomal protein with 52–53 animo acids or 76–78 amino acids. Ubiquitin extension proteins have been paid attention that they play important roles in responding to stresses and regulating certain developmental processes in plants. We describe here the isolation, sequence characteristics and expression analysis of ZmERD16 gene encoding a homologue of ubiquitin extension protein. ZmERD16 includes a 390 bp open reading frame (ORF) encoding an ubiquitin monomer followed by 53 animo acids, with a predicted molecular mass of 14.7582 kD and pI of 9.94. The genomic DNA and the promoter region of ZmERD16 were obtained by PCR method. The genomic DNA was composed of four exons and three introns. Promoter had some motifs that were related to light, stress, defense, development, auxin and other stresses. The tissue-specific expression analysis suggested that ZmERD16 was constitutively expressed in maize different tissues. Quantitative real-time RT-PCR results showed ZmERD16 was a multiple stresses inducible gene, induced by various stresses, such as salt, dehydration, cold, heat, PEG, methy jasmonat (MJ) and salicylic acid (SA), but not by ABA and 2,4-D. These results suggested that ZmERD16 might play an important role in various signal transduction pathways of stresses in plant.

Comparison of Genetic Diversity between Peanut Mini Core Collections from China and ICRISAT by SSR Markers

JIANG Hui-Fang, REN Xiao-Peng, ZHANG Xiao-Jie, HUANG Jia-Quan, LEI Yong, YAN Li-Ying, LIAO Bo-Shou, Hari D UPADHYAYA, Corley C HOLBROOK

Acta Agron Sin. 2010, 36(07):  1084-1091.  doi:10.3724/SP.J.1006.2010.01084

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A core collection or mini core is a subset of accessions from the entire collection that covers most of available genetic diversity of a species. Extensive investigation of core collections is an efficient approach to enhance evaluation and utilization for crop germplasm. The mini core collections of peanut (Arachis hypogaea L.) from China consisting of 298 accessions and from International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) consisting of 168 accessions were comparatively analysed by SSR method. Twenty six polymorphic SSR markers screened from 206 primer pairs were used to investigate the similarity and genetic distance among the peanut accessions involved. The similarity coefficients between the genotype pairs among the 466 accessions ranged from 0.49 to 0.99. The largest genetic distance was between L2 Gangguo (a Chinese genotype) and ICG12625 (an ICRISAT genotype) with a similarity coefficient of 0.49. Among the six botanical types in peanut, accessions of fastigiata and hypogaea were more diversified than other types. There was considerable genetic difference between the Chinese peanut accessions and some ICRISAT accessions especially with the aequatoriana genotype ICG12625. The genetic diversity was greater among the Chinese peanut mini core than that among ICRISAT mini core in terms of the similarity coefficient and genetic diversity index.

QTL Mapping of Agronomic and Quality Traits in Soybean under Different Post-Flowering Photoperiods

WANG Ying, CHENG Li-Rui, LENG Jian-Tian, WU Cun-Xiang, HOU Wen-Sheng, HAN Tian-Fu

Acta Agron Sin. 2010, 36(07):  1092-1099.  doi:10.3724/SP.J.1006.2010.01092

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Most of agronomic and quality traits of soybean (Glycine max L. Merr.) are quantitatively inherited, and sensitive to photoperiod. In this study, 181recombinant inbred lines (RIL) of F₁₀ generation were used to analyze the post-flowering photoperiod effects on yield and quality traits of soybean, and 129 SSR markers were used to map QTLs associated with the above traits under both long day (LD) and short day (SD) conditions and their photoperiod sensitivity (PS). The results showed that photoperiod greatly affected the performances of agronomic and quality traits of soybean, and the photoperiod sensitivity of the traits were plant height.node number on the main stem>protein content and oil content>100-seed weight>pod number per plant>total percentage of protein and oil. By using CIM (composite interval mapping) method, a total of 12 QTLs associated with the agronomic and quality traits and their sensitivity to the post-flowering photoperiod were identified and mapped on eight linkage groups including A1, A2, B1, B2, C1, D1a, F and L. Among the QTLs mentioned above, four were identified under SD and could explain 11.37%–26.63% of phenotypic variation, and three were identified under LD condition and could explain 11.84%–27.85% of phenotypic variation. The other five were associated with photoperiod sensitivity of various traits and could explain 6.15%–21.44% of phenotypic variation. For the same individual agronomic or quality trait, no major QTL was detected under both SD and LD, indicating that post-flowering photoperiod dramatically regulates the expression of genes determining yield and quality traits, and the agronomic and quality traits of soybean are sensitive to environmental factors. It was drawn that photoperiod sensitivity is a key index for adaptability improvement of soybean. For breeding elite varieties with ideal yield potential, quality and stress tolerance, the photoperiod-insensitive genes related to various traits should be explored and pyramided with other needed genes.

Simulation Comparisons of Effectiveness among QTL Mapping Procedures of Different Statistical Genetic Models

SU Cheng-Fu, ZHAO Tuan-Jie, GAI Jun-Yi

Acta Agron Sin. 2010, 36(07):  1100-1107.  doi:10.3724/SP.J.1006.2010.01100

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QTL mapping has emerged based on the development and integration of molecular genetics and quantitative genetics. Along with the establishment and improvement of QTL mapping procedures, a great number of studies of QTL mapping in various crop species have been carried out. QTLs detected with high accuracy can be used for marker-assisted selection and map-based cloning, while the false-positive QTLs are meaningless, even mislead their usefulness. In the present study, the recombinant inbred line (RIL) populations were simulated based on four kinds of genetic models, including Model I, additive QTL; Model II, additive and epistatic QTLs; Model III, additive QTL and QTL×Environment interaction, and Model IV, additive, epistatic QTLs and QTL×Environment interaction. Two sets of RIL data for each of the four models were obtained, in a total of eight sets of RIL data designated as M-1~M-8. Six QTL mapping procedures, i.e. CIM (Composite interval mapping), MIMF (forward search of multiple interval mapping) and MIMR (regression forward selection of multiple interval mapping) of WinQTL Cartographer Version 2.5, ICIM (Inclusive composite interval mapping) of IciMapping Version 2.0, MQM (multiple-QTL model) of MapQTL Version 5.0, and NWIM (interval mapping) of QTLnetwork Version 2.0 were used for detecting QTLs of the eight sets of RIL data. The results showed: (1) Different mapping procedures fit different genetic models. CIM and MQM were only suitable for Model I data. MIMR, MIMF and ICIM were only suitable for Model I and Model II data. Only NWIM was suitable for all four models’ data. Therefore, the data from different genetic models corresponded to different optimal QTL mapping procedures. (2) Since the genetic model of the practical experimental data was unknown, a multiple model mapping strategy should be taken, i.e. a full model scanning with complex model procedure, such as QTLnetwork 2.0, followed by verification with another procedure corresponding to the scanning results.

QTL Analysis for Mesocotyl Length in Rice(Qryza sativa L.)

HUANG Cheng, JIANG Shu-Kun, FENG Ling-Ling, XU Zheng-Jin, CHEN Wen-Fu

Acta Agron Sin. 2010, 36(07):  1108-1113.  doi:10.3724/SP.J.1006.2010.01108

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To understand genetic basis underlying the relationship between mesocotyl elongation and hormone (GA) in rice (Oryza sativa L.), we genetically analyzed RILs population derived from a cross between two japonica rice cultivars, Shennong 265 (long mesocotyl) and Lijiangxintuanheigu (short mesocotyl), with its linkage map. QTLs for mesocotyl length were detected under water and GA germination conditions. The results showed that GA at 1.50 mmol L^-1 stimulated mesocotyl elongation dramatically. Total five QTLs for rice mesocotyl length, each accounting for 7% to 33% of the phenotypic variance (VE), were detected on chromosomes 1, 2, 3, 6, and 11 under two germination conditions (environments). The LOD value of each QTL was ranged from 3.65 to 15.52. Among the five QTLs, qML3, qML6, and qML11 were detected under both germination conditions and qml1 and qml2 were identified only under water germination condition. In comparison with other studies revealed that major QTL qML3 was easily re-detected in different populations and environments.

Molecular Markers for Estimating Distinctness, Uniformity, and Stability of Wheat Lines in Regional Trials

WANG Li-Xin, CHANG Li-Fang, LI Hong-Bo, JI Wei, LIU Li-Hua, ZHAO Chang-Ping

Acta Agron Sin. 2010, 36(07):  1114-1125.  doi:10.3724/SP.J.1006.2010.01114

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To determine the molecular markers for testing the distinctness, uniformity，and stability (DUS) of wheat (Triticum aestivum L.) lines in regional trials, 145 wheat cultivars were used to screen 1 334 pairs of primers of SSR, EST-SSR, and AFLP-SCAR markers. According to the even distribution of molecular markers on 21 wheat chromosomes, the higher polymorphism information content (PIC), the clear PCR bands, the easy discrimination of different alleles, and the stable PCR amplification, 105 pairs of primers, including 63 pairs of SSR primers, 21 pairs of EST-SSR primers, and 21 pairs of AFLP-SCAR primers, were selected for wheat cultivar (lines) DUS testing. A total of 754 alleles at 122 loci can be identified with 105 pairs of primers, with 5.8 loci per chromosome and 7.2 alleles per locus on average. The three kinds of molecular markers can amplify the DNA fragments that are inside/outside of genes and repeative/non-repetitive sequences. The 105 pairs of primers were classified into 21 pairs of core primers and 84 pairs of standby primers based on their pattern definition, distribution on 21 chromosoms, and PIC value. The 21 core primers distributing on 21 chromosoms could determine the distinctness test for about 80% of total cultivars (lines), the seed purity test for 95%, and the uniformity and stability test for 60%. The 84 standby primers were used as the first grade (29 pairs) and the second grade (55 pairs) to the homozygous DNA locus ratio of lines with no-homozygous loci of coer markers and the genetic similarities or the distinctness of similar cultivars (lines) pairs revealed by the core primers. At the same time, we determined the seed purity for the other 5% of lines. These 105 pairs of primers could finish DUS test for more than 90% of lines in the winter wheat regional trials in 3 cropping seasons from 2006 to 2009. Although less than 10% of lines should be evaluated in combination with phenotypic identification in the field, the effectiveness and efficiency of the 105 pairs of primers are satisfactory in bulk screening for wheat DUS test.

Wheat Leaf Rust Resistance in 28 Chinese Wheat Mini-Core Collections

DING Yan-Hong, LIU Huan, SHI Li-Hong, WEN Xiao-Lei, ZHANG Na, YANG Wen-Xiang, LIU Da-Qun

Acta Agron Sin. 2010, 36(07):  1126-1134.  doi:10.3724/SP.J.1006.2010.01126

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Leaf rust of wheat caused by Puccinia triticina Erikss is an important wheat disease worldwide. Application of resistant cultivars is considered as the most economical, environment-friendly, and effective way to control this disease. Wheat (Triticum aestivum L.) core collections act as an important germplasm resource for resistance breeding to leaf rust in China. To evaluate the leaf rust resistance of Chinese wheat mini-core collections, we chose 28 accessions with a wide range of leaf rust reaction (R, SR, MS and S) were chosen for resistance identification in seedling and adult stages and gene postulation. Thirty-nine near isogenic lines (or single gene lines) in Thatcher background with known leaf rust resistance genes were used as differential hosts. All genotypes were inoculated with eight pathotypes of P. triticina at seedling stage. The results indicated that Lr2b, Lr3bg, Lr10, Lr11, Lr14a, Lr16, Lr17, Lr20, Lr33, and some unknown resistance genes might exist. As revealed by 19 molecular markers that are closely linked or co-segregated with part of the known Lr genes, the 28 accessions from wheat mini-core collections were postulated to carry thirteen resistance genes, such as Lr17, Lr2b, Lr14a, Lr33 in Xinkehan 9; Lr26, Lr36, and Lr37 in Xingyi 4; Lr2b and Lr34 in Zipi; Lr1 in Dabaipi; Lr1, Lr10, and Lr34 in Bihongsui; Lr10 in Zhongyou 9507; Lr1 and Lr34 in Xiaobaimai, Hongli Dangnianlao, Laomai, Chanbuzhi, Sumai 3, and Chejianzi; Lr1, Lr34, Lr14a, and Lr2binHonghuazao; Lr34 in Jiangxizao, Paozimai, Sanyuehuang, Youmang Saogudan, Fuyanghong, Chengdu Guangtou and Jiangmai; Lr28 in Dunhua Chunmai and Gansu 96; Lr34, Lr16, Lr11, Lr3bg and Lr33 in Orofen; Besides, Xinkehan 9, Xingyi 4, Honghuazao, Hongli Dangnianlao, Orofen, Youmang Saogudan, Chengdu Guangtou, Gansu 96, Xiaohongpi, Dingxingzhai, Zhongyou 9507, and Hongdongmai may carry un-known resistance genes to leaf rust. However,the specific bands for Lr9, Lr19, Lr20, Lr21, Lr24, Lr29, Lr35, Lr38,and Lr47 were not amplified with the corresponding primers in the 28 accessions. This indicated that Lr9, Lr19, Lr20, Lr21, Lr24, Lr29, Lr35, Lr38,and Lr47 were not present in the 28 accessions. The occurrence degree of leaf rust at adult stage showed that 17 of 28 tested materials may carry slow rusting resistance genes and adult resistance genes. The results also showed that the resistance genes in response to leaf rust disease is relatively richer in the 28 Chinese wheat mini-core collections, and the Chinese wheat mini-core collections can be applied in breeding programs of leaf rust resistance.

Isolation and Expression of Two Fruit Ripening Related Genes SlPEL and SlAPL in Tomato (Solanum lycopersicum)

XIAO Dong, XIAO Yang, CA Ying-Fan, DENG Xiao-Feng, TUN Suo-Wei, ZHENG Xu, LI Wan-Chen, TUN Cui-Beng, BI Zhang-Jun, NIU Ying-Ze, YANG Jian-Beng

Acta Agron Sin. 2010, 36(07):  1135-1143.  doi:10.3724/SP.J.1006.2010.01135

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During ripening, fruits undergo complicated developmental changes with varying physiological and biochemical activities that affect color, flavor, and texture. In tomato, these changes include accumulation of ethylene, the red pigment lycopene and the cell wall hydrolase, polygalacturonase (PG). Recently, genes of PG, pectin esterase (PE), ACC synthetase, ACC oxidase, and ethylene syshetase etc. from tomato, banana, carica papaya, peach and mango have been cloned. In this report, a large tomato expressed sequence tag (EST) dataset (152 635 in total) from 27 different EST libraries was analyzed to gain insights into digital gene expressions of two fruit ripening related genes SlPEL and SlAPL in tomato. Their expression profiles were detected using semi-quantitative RT-PCR assays and real-time RT-PCR assays in tomato (cv. Meiweiyingtao) during fruit development and ripening. SlPEL expression increased in the fruit at 12 days after pollination, and reached the small peak 4-6 days later and the larger peak at 28 days after pollination; then dropped to the level of the small peak until red ripening stage. As SlPEL, SlAPL expression was also induced by the fruit ripening. But SlAPL expressed two weeks later than SlPEL. SlPEL expression achieved the small peak at 28-32 days after pollination and the large peak at 39 days after pollination; and kept the higher levels until red ripening stage. The results confirmed that the digital gene expression using different EST libraries is an effective way to check the research value genes.

Identification and Comparison of diploid and Tetraploid Hybrids of Oryza sativa X O.meyeriana

SONG Zhao-Jian,DU Chao-Qun,HU E-Ping,TANG Zhi-Qiang,CHEN Dong-Ling,HE Yu-Chi

Acta Agron Sin. 2010, 36(07):  1144-1152.  doi:10.3724/SP.J.1006.2010.01144

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Genomic in situ hybridization (GISH) was used to identify the trueness of diploid and tetraploid hybrids of Oryza sativa and O. meyeriana in this research. To explore the effect of polyploidization on diploid hybrid, compared and analyzed the cause of sterility and the application potency of hybrids, the agronomic traits and meiosis of diploid and tetraploid hybrids. GISH detection proved the trueness of hybrids, since O. meyeriana chromosomes gave off red fluorescence signals, while cultivated rice chromosomes had no signals. Many agronomic traits, such as plant height, flag leaf length, spikelets per panicle, spikelet length and width of tetraploid hybrid increased much more than those of diploid hybrid, showing obvious predominance of polyploid. The meiosis behaviors of diploid and tetraploid hybrids were also different from each other. The meiosis was disorder in diploid hybrid, but normal in tetraploid hybrid. Doubling of chromosomes improved the meiosis obviously, but tetraploid hybrid was still acarpous which may be related to the nucleo-cytoplasmic incompatibility. But the hybrids had the potential to be modified in rice breeding. Their characteristic of non-awn will also play an important part in genetic research and awn improvement in rice.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Effects of Planting Density on Yield Performance and Density-Tolerance Analysis for Maize Hybrids

CHEN Chuan-Yong, HOU Yu-Hong, SUN Rui, ZHU Ping, DONG Zhi-Qiang, ZHAO Ming

Acta Agron Sin. 2010, 36(07):  1153-1160.  doi:10.3724/SP.J.1006.2010.01153

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Plant density has been recognized as a major factor determining the grain yield. The photosynthetic performance changes as the density increases. The main objective of this research was to evaluate the response of the photosynthetic performance to planting densities in different hybrids of maize (Zea mays L.). Field experiments were conducted in Gongzhuling, Jilin province. Three corn hybrids were cultivated at 60 000 plants ha^-1, 75 000 plants ha^-1, 90 000 plants ha^-1 and 105000 plants ha^-1. Treatments were arranged in a split-plot design with three replications. Plant population density was the main-plot and hybrids the subplot. The results indicated that leaf area index (LAI), leaf area duration (LAD), mean leaf area index (MLAI), ear number m^-2(EN) increased and net assimilation rate (NAR), harvest index (HI), grains per ear (GN), grain weight (GW) decreased in all hybrids as plant density intensified, as a result, the assimilate transmission rate reduced, the leaf senescence accelerated, physiological activity declined. During the growth period, the changes of LAI, LAD showed a single peak curve. The peak of LAI appeared at silking, the peak of chlorophyll content appeared at grain filling and peak of high value duration of LAD appeared from full-grown to milky maturity. The peak of NAR appeared from seeding stage to jointing and from silking to grain filling respectively. The photosynthetic characteristics were different in plant density treatments. The highest grain yield of Xianyu 335, Zhengdan 958, Jidan 209 was obtained in the treatments of 90 000 plants ha^-1, 75 000 plants ha^-1, 90 000 plants ha^-1 respectively. Kernel yield per plant decreased in all hybrids as plant density intensified. The density-tolerance of hybrids was Xianyu335>Zhengdan958>Jidan209. The suitable planting density range was 90 000–105 000 plants ha^-1 for Xianyu 335, and 75 000–90 000 plants ha^-1 for Zhengdan 958 and Jidan 209.

Moisture Variationand Modeling of Cotton and Soybean Seeds under Different Storage Conditions

WANG Jing, JIANG Peng, LI Dong, MA Jiang, TAII Shu-Jin, ZUO Zhen-Peng, DONG Lu-Hao

Acta Agron Sin. 2010, 36(07):  1161-1168.  doi:10.3724/SP.J.1006.2010.01161

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The seed equilibrium moisture is an important indicator in evaluating dynamic changes of seed moisture absorption or moisture desorption. In this study, soybean and cotton seeds with different initial moisture contents (IMC) were used to explore the laws of the seed moisture absorption or moisture desorption under different storage conditions(temperature and humidity). The soybean seeds presented moisture desorption when the storage temperature(ST) was 15℃, 25℃, 40℃ and the relative humidity (RH) was less than 18.78% (4% IMC) or 48.10% (8% IMC and 12% IMC), and presented moisture absorption in other storage conditions. The cotton seeds presented moisture desorption under conditions of ST=15℃ and RH<7.49% (4% IMC), 18.78% (8% IMC) or 48.10% (12% IMC). The cotton seeds also presented moisture desorption when ST=25℃, RH<18.78% (4% IMC) or 48.10% (8% IMC and 12% IMC), or ST=40℃, RH<7.49% (4% IMC) or 48.10% (8% IMC and 12% IMC), and moisture absorption in other storage conditions. The safety water content of the cotton seeds with 4% IMC under the condition of ST=15℃ and RH>55%, ST=25℃ and RH>55%, or ST=40℃ and RH>50% was 10.5%, 9.5% and 6.5%, respectively. For cotton seeds with 8% IMC, the safety water content under the condition of ST=15℃ and RH>60%, ST=25℃ and RH>55%, ST=40℃ and RH>45% was 10.5%, 9.5% and 6.5%, respectively. The cotton seeds with 12% IMC had the same safety water content under the condition of ST=15℃ and RH>55%, ST=25℃ and the RH>55% or ST=4℃ and RH>45%. The equilibrium moisture of Liaodou 11 with 4%, 8% and 12% IMC under the condition of ST=15℃ and RH>65%, ST=25℃ and RH>55% or ST=40℃ and RH>45% was above its safety water content (12%, 11%, and 8%). The RH which was above its safety water content of Hedou 13 was about 5% higher than that of Liaodou 11. The equilibrium moisture was above its safety water content when ST=15℃, 25℃ and RH>55% or ST=40℃ and RH>60% for cotton seeds; As well as when ST=25℃ and RH>55% or ST=25℃, 40℃ and RH>60% for soybean seeds. The predictive model of equilibrium time (d) depends on IMC (x), RH (y) and temperature (z) was d =36.97+1.78x–0.58y–0.58z–0.016xy–0.021xz–0.0012yz +0.007y² for cotton seeds, and d=23.29+3.72x–0.19y–0.86z–0.02xy–0.09xz–0.008yz+0.005y²+0.03z² for soybean seeds. Through the model test, F<2.39, which indicated that the conformity was high between the predictive value and the test value. The predictive model for Hedou 13 was d=48.64+0.36x–0.44y–1.49z–0.008yz+0.006y²+0.026z². The predictive models we constructed are very useful in predicting moisture equilibrium time.

Antioxidative Activities of Transgenic Yeast with Ferritin Gene from Wheat

ZHAO Yong-Liang, CHEN Jing, WANG Dan, WANG Wei-Guo, LI Yun-Hui

Acta Agron Sin. 2010, 36(07):  1169-1175.  doi:10.3724/SP.J.1006.2010.01169

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Ferritin, a key protein to store iron, is widely distributed in animal, plant, and microbe. Ferritin can regulate the balance in iron metabolism and decrease the oxidative damage caused by ferrous ion. It is generally recognized that the antioxidant activity of ferritin is mainly caused by integrating ferrous ion among cells, and thereby decreasing the generation of Fenton reaction. In addition to the antioxidant pathway against hydrogen peroxide (H₂O₂), less information is available on other antioxidative pathways and mechanism of ferritin. In this study, a ferritin gene was cloned from wheat (Triticum aestivum L.), and its expression vehicle of eukaryotic cell was constructed and transformed into yeast (Saccharomyces cerevisiae). Compared with the control yeasts, the transgenic yeasts were able to scavenge H₂O₂,O₂^?and ·OH effectively. The half lethal density (LD₅₀) of transgenic yeasts induced by the three types of active oxygen (·OH, O₂^?and H₂O₂) was 0.40, 1.00, and 36.91 mmol L^-1, which increasedby37.93%, 47.06%, and 77.03% compared with the control respectively. The abilities for eliminating ·OH, O₂^?, and H₂O₂ of the trsnsgenic yeast per unit concentiation were quantitated with cubic polynomial, logarithmic, and negative exponential equations based on yeast concentration respectively. These results demonstrated that expressed products of wheat ferritin gene in eukaryotic orgamism can effectivly in eliminate various types of active oxygen with different and complex mechanisms.

Nonlinear Screening Indexes of Drought Resistance at Rice Seedling Stage Based on Support Vector Machine

YUAN Zhe-Ming, TAN Xian-Sheng

Acta Agron Sin. 2010, 36(07):  1176-1182.  doi:10.3724/SP.J.1006.2010.01176

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Screening indexes of drought resistance in crops is a puzzler with a few samples, multi-index and non-linear characteristics. Rationality of linear regression model and the indexes obtained by linear screening based on empirical risk minimization are debated. On the contrary, support vector machine based on structural risk minimization has the advantages of non-linear characteristics, fitting for a few samples, avoiding the over-fit, strong generalization ability and high prediction precision, etc. In this paper, setting the survival percentage under repeated drought condition as the target and support vector regression as the nonlinear screen tool, six integrated indicators including plant height, proline, malondialdehyde, leaf age, area of the first leaf under the central leaf and ascorbic acid, were highlighted from 24 morphological and physiological indicators in 15 paddy rice cultivars. The results showed that support vector regression model with the six integrated indicators had a more distinct improvementin fitting and prediction precision than the linear reference models. Considering the simplicity of indicators measurement, the support vector regression model with the only six morphological indicators including shoot dry weight, area of the second leaf under the central leaf, root shoot ratio, leaf age, leaf fresh weight and area of the first leaf under the central leaf was also feasible. Furthermore, an explanatory system including the significance of regression model and the importance of single indicator was established based on support vector regression and F-test.

Effects of Delayed Irrigation at Jointing Stage and Irrigation Level on Consumption Amount and Resources of Water in Wheat and Farmland Evapotranspiration

WANG Hong-Guang, YU Zhen-Wen, ZHANG Yong-Li, WANG Dong

Acta Agron Sin. 2010, 36(07):  1183-1191.  doi:10.3724/SP.J.1006.2010.01183

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Water-saving irrigation is a hotspot in cultivation research of winter wheat (Triticum aestivum L.). Many investigations have been carried out to reduce the irrigation frequency and water amount. However, the conclusions are quite different due to the great discrepancies on precipitation and experimental condition. In this study, a strategy of water-controlled irrigation based on measuing soil water content was adopted, and several delayed irrigation treatments were tested for their effects on water consumption, water use efficiency (WUE), and wheat yield in two sites of Shandong province, China in 2007–2008 and 2008–2009 growing seasons. The expected water content of 0–140 cm soil layer was designed for 65–80% in different treatments, and two irrigations were given at jointing or 10 d after jointing and flowering stages. In the treatments irrigated at the same time, the daily water consumption from jointing to flowering stage and the water consumption amount in the whole growth duration increased with promoting the level of supplemental irrigation, but the soil water consumption amount in 0–120 cm soil layer decreased. The consumption amount of soil water showed an increase–decrease trend, and its percentage to the total water consumption amount decreased. Simultaneously, the comsumption percentage of precipitation to the total water consumption amount was also reduced. Under the same irrigation level, compared with normal irrigation at jointing, the delayed irrigation (at 10 d after jointing) reduced the daily water consumption from jointing to 10 d after jointing stage, but promoted the daily water consumption at flagging stage. From jointing to flowering stage, the comsumption amont of soil water in 80–120 cm soil layer, the total water comsumption amount increased with the more irrigation water supplied. However, the comsumption percentages of precipitation, supplemental irrigation, and soil water were in minor changes.At early filling stage, the flag leaf area and the transpiration per unit area of soil decreased and the evaporation increased in the delayed irrigation treatment. Although reduced spike number per hectare, the grain number, thousand-grain weight, grain yield, WUE, and irrigation production efficiency were higher in the delayed irrigation treatment than in the treatment of irrigation at jointing stage. Under the experimental condition (2007–2008 growing season), the first supplemental irrigation at 10 d after joining with a relative water content of 75% in 0–140 cm soil layer and the second irrigation at flowering with a relative water content of 70% were considered to be an optimal water-saving management for wheat high-yielding production.

Grain Yield and Agronomic Traits of Winter Wheat Varieties in Response to Fertilization in Dryland

ZHOU Ling, WANG Zhao-Hui, LI Sheng-Xiu

Acta Agron Sin. 2010, 36(07):  1192-1197.  doi:10.3724/SP.J.1006.2010.01192

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The effects of phosphorus and nitrogen fertilizers on yield and its components have been widely studied in wheat (Triticum aestivum L.), and it is generally understand that phosphorus fertilizer has the increase potential of spike number and 1000-kernel weight, whereas, nitrogen fertilizer may promote the spike number and grain number per spike but reduce the 1000-kernel weight. However, these conclusions were obtained in studies with high inputs of phosphorus and nitrogen. To gain insights into the effect of fertilizer input level on the yield response of wheat in dryland, we planted nine winter wheat varieties in the field where no fertilizer applied for six years. Compared with the control (zero input of fertilizer), dry matter and kernel yield increased by 17% and 20% in the treatment of low fertilizer, and by 35% and 40% in the treatment of high fertilizer, respectively. In the low-fertilizer treatment, spike number and kernel number per spike were 11% and 8% greater than those in the control, respectively. In the high-fertilizer treatment, larger values of the two traits were observed (25% and 10%, respectively). The increments of dry matter, spike number, and kernel number per spike were greater in high-yielding varieties than in low-yield ones, showing a stronger response of high-yielding variety to the input of fertilizer. However, there was no effect of fertilizer rate on 1000-kernel weight. The results implied that yield, dry matter, spike number, and kernel number per spike of different varieties had diverse responses to the level of fertilizer input under dryland condition. High-yielding varieties were characterized with high levels of dry matter, spike number, and kernel number per spike, and their sensitive responses to fertilizer rates contributed greatly to higher yields when more fertilizer was applied.

Vascular Anatomical Traits of Caryopsis in Different Positions and Its Relationship with Quality Traits of Japonica Rice

YU Xiao-Gang, ZHANG Wen-Zhong, HAN Ya-Dong, HUANG Li-Li, XU Hai, ZHAO Ming-Hui, GAO Dong-Chang, XU Zheng-Jin, CHEN Wen-Fu

Acta Agron Sin. 2010, 36(07):  1198-1208.  doi:10.3724/SP.J.1006.2010.01198

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Typical Japonica rice Liaojing294 and Yanfeng47 were used to analyze the dorsal vascular anatomical traits of caryopsis and its relation to grain quality traits on primary and secondary rachises at 4–22 days after flowering (DAF). The results indicated that the section of dorsal vascular bundle was all near ellipse and its area and short axis length changed as parabola along with development of caryopsis of these two varieties. Caryopsis weight reached the maximum value at 12 DAF for Liaojing 294 and at 10 DAF for Yanfeng 47, respectively. The long axis length showed a monotonic increaseranked as follows: grains on top primary rachis > grains on bottom primary rachis > grains on top secondary rachis > grains on bottom secondary rachis. And these values of Liaojing 294 were larger than those of Yanfeng 47 at the same grain position. There was significantly negative correlation of the section area of vascular bundle and its long axis length with chalky rice rate and chalkiness. A significantly positive correlation of the vascular section area, long axis length, short axis length, sieve tube width and vessel number with caryopsis dry weight, caryopsis plumpness and grain plumpness was identified. So, the structure of dorsal vascular bundle is considered as the important morphological and anatomical basis for the difference of rice chalkiness, caryopsis plumpness and other organic matter accumulation related characters. with caryopsis development and grain filling. The dorsal vascular bundle, that is composed of centered vessels and circumjacent sieve tubes, showed a shape trend of wide to thin from bottom to top. At the same DAF, the vascular section area, long axis length, short axis length, sieve tube width, vessel number, caryopsis volume and caryopsis dry weight of these two varieties were all

RESEARCH NOTES

Effect of Genotype and Growing Environment on Anther Culture in Wheat

HAN Xiao-Feng, DAO Li-Li, YIN Gui-Xiang, LIU Xiao-Lei, DU Li-Pu, WEI Yi-Qi, YAN Yue-Ming, YE Xing-Guo

Acta Agron Sin. 2010, 36(07):  1209-1215.  doi:10.3724/SP.J.1006.2010.01209

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Wheat anther culture is affected greatly by many factors, such as wheat genotype, culture medium, and the temperature during the growing period of donors. For further improving the regeneration efficiency from wheat anthers and understanding the genetic control of wheat anther culture ability, some wheat genotypes including Verry, Xinchun 9, Chinese Spring, and Ningchun 4, and their F_{1 hybrids by crossing each other were used for anther cultures in different years, and the callus induction frequencies were evaluated. The results indicated that haploid calli were easily induced from the anthers of Alondra, Verry, Shi 4185, Xinchun 9, and Bainong 3217. The frequency of callus production ranged from 25.3% to 51.9%. Shi 4185 and Xinchun 9 showed higher potentials for wheat haploid breeding because of their good agronomic traits and high anther culture response. Some F1environment conditions for the donor plants of the anthers were long vegetative growing period, moderate temperature during the tillering period, and high temperature during the hybrids derived from Ningchun 4 had high callus production rates, indicating that Ningchun 4 had high combining ability with some crossing parents in anther culture. However, the F1 hybrids from the parents with high anther culture response were not certain to perform high callus frequency, which was more than 10.0% in majority of the crosses. This suggested that the genetic control of wheat anther culture appeared to be complicated and performed as a quantitative trait. The optimal late jointingperiod. Haploid plantlets could be induced directly from wheat anthers in the liquid media with low concentrations of auxin and glucose. It was also found that 2,4-D was better than dicamba in liquid media for callus induction. Besides, the frequency of callus induced from wheat anthers showed increase trend with the promotion of temperature during the growing period of wheat donor plants, which was caused by climate warming.}

FISH Analysis of Resynthesized Allotetraploid Arabidopsis

LI Fang, ZHANG Gai-Sheng

Acta Agron Sin. 2010, 36(07):  1216-1220.  doi:10.3724/SP.J.1006.2010.01216

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Allopolyploidy breeding or introduction of preferential gene(s) via allopolyploidization is widely attempted in production of new crops. Thus at the onset of establishment of new allopolyploids, the functional gametes are reproduced conditioning that normal events such as synapsis and pairing and correct segregation of homologous chromosomes are guaranteed with the avoidance of possible interference of homoeologous chromosomes during meiosis. In the present study, we reported on meiotic synapsis and pairing of homologous chromosomes during the development of pollen mother cells in the newly resynthesized allotetraploid Arabidopsis aided with DAPI staining and FISH technique. The results showed that the correct number of nuclear chromosomes and balanced segregation were frequently observed with DAPI staining, and FISH analysis further provided the improved resolution of synapsis and pairing of homologous chromosomes, and the investigated nuclear chromosomes derived from different parental lines had no interference with each other, and the synapsis and pairing of homologous chromosomes were clearly identified. Therefore, the results indicated that the newly resynthesized allotetraploid Arabidopsis may achieve the normal meiosis and propagate the functionalized gametes for fertilization, confirming a potential vigor of intra/interspecific hybridization and a cytological basis for allopolyploid breeding.

Cloning and Expression Analysis of a bZIP Transcription Factor Gene in Wheat Induced by Stripe Rust Pathogen

ZHANG Yi, XIA Ning, ZHANG Gang, GUO Jun, HUANG Li-Li, KANG Zhen-Sheng

Acta Agron Sin. 2010, 36(07):  1221-1225.  doi:10.3724/SP.J.1006.2010.01221

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In plant, basic leucine zipper (bZIP) transcription factors play various roles in developmental processes and in response to biotic and abiotic stimuli. In the present study, a novel bZIP gene, designated as TabZIP, was isolated from wheat leaves infected by Puccinia striiformis f. sp. tritici using in silico cloning and reverse transcription PCR approaches. TabZIP was predicted to encode a 356 amino-acid protein, which contained a bZIP transcription factor basic domain signature and a leucine zipper motif. Multiple alignment analysis based on the amino acids encoded by different bZIP genes from rice (Oryza sativa), maize (Zea mays), Arabidopsis thaliana, indicated that TabZIP was conserved among the three species of plants with highly sequence similarity. The transcript level of TabZIP was relatively high in root, but low in stem and leaf. Real-time PCR analysis revealed that TabZIP gene was rapidly and dramatically induced during incompatible interaction, whereas there was no significant effect in compatible interaction. Meanwhile, the expression of TabZIP was also induced by exogenous methyl jasmonate and ethephon. On the basis of these results, we postulate that the transcription factor encoded by gene TabZIP may be involved in wheat defense response to stripe rust fungus infection through ethylene- or jasmonic acid-dependent signal transduction pathways.

Effects of Planting Density and Row Spacing on Canopy Apparent Photosynthesis of High-Yield Summer Corn

YANG Ji-Shun, GAO Hui-Yuan, LIU Peng, LI Geng, DONG Shu-Ting, ZHANG Ji-Wang, WANG Jing-Feng

Acta Agron Sin. 2010, 36(07):  1226-1233.  doi:10.3724/SP.J.1006.2010.01226

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With different plant population densities (6.75´10⁴, 9.00´10⁴, and 11.25´10⁴ plants ha^-1), the effects of the deneity and row spacing on grain yield and canopy apparent photosynthesis were studied in this article. The results were as follows: with the increase of planting density, grain yield, leaf area index (LAI) and capture efficiency of photosynthestically active radiation(PAR) in upper leaf layer, as well as canopy apparent photosynthesis (CAP) and canopy respiration (CR) and dry matter quantity increased accordantly; but, chlorophyll content and capture efficiency of PAR in the middle and lower layers of canopy decreased. Within different row spacing treatments, the wide-narrow row spacing were not superior to the uniform one significantly at 6.75´10⁴ plants ha^-1. However, at 9.00´10⁴ and 11.25´10⁴ plants ha^-1, grain yield, LAI, chlorophyll content, capture efficiency of PAR in middle leaf layer and average rate of CAP after anthesis in row spacing of “80 cm+40 cm” were remarkably higher than those in other three row spacings (uniform, 70 cm + 50 cm, 90 cm + 30 cm); while CR/TCAP (ratio of canopy respiration to total canopy apparent photosynthesis) in row spacing of ’80 cm+40 cm’ was the lowest, compared to the others. From the above, it was suggested that at higher plant density the row spacing of ’80 cm+40 cm’ could enlarge photosynthetic area, enhance PAR in middle leaf layer, increase CAP, reduce CR and improve grain yield.