Table of Content

12 April 2010, Volume 36 Issue 4

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Cloning and Analysis of GmCIL4 Gene in Glycine max L.

ZHANG Qing-Zhe,MA Jin-Hua,CHEN Xin-Jian,FU Yong-Fu

Acta Agron Sin. 2010, 36(4):  539-548.  doi:10.3724/SP.J.1006.2010.00539

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The model plant Arabosopsis thaliana has been identified to have four major flowering pathways. Among them, the photoperiod pathway integrates the light signal including light/dark cycle, light spectrum, light intensity, and light duration, to mediate flower initiation. CONSTANS(CO) is a key gene in photoperiodic flowering pathway and acts between genes of the circadian clock and meristem identity. CO encodes a protein containing two zinc finger regions (B-box I and II) near the amino terminus and a CCT (CO, CO-Like, TOC1) domain near the carboxy terminus. The CO from Arabidopsis thaliana is one member of the family comprised of 17 members, which can be classed into three subgroups based on their characters of functional domains. To elucidate the function of CO in flowering in soybean, cloned one of CO-like gene, named as GmCOL4, from Glycine max L. Kennong 18. Bioinformatics analysis revealed that GmCOL4 encoded a protein embedded two conserved domains, B-box and CCT, and belonged to subgroup III. Phylogenetic analysis based on the critical amino acid sequences indicated that GmCOL4 was much close to COL9 with similarity of 64.3%. The expression profiles of GmCOL4 by quantitative real-time RT-PCR (qRT-PCR) showed a similar pattern to that of COL9. GmCOL4 was largely regulated by biological circadian, while the light appeared weak effect on it. And GmCOL4 expressed mainly in leaves and had its highest amount in anthesis. The results suggested that GmCOL4 is one of the important genes in the regulation of flowering and photoperiodic in soybean. It paves a way to study the function of CO family in soybean and its application in soybean molecular breeding.

Origin Analysis of Resistance Gene to Soybean Mosaic Virus in Soybean Line ICGR95-5117

GUAN Rong-Xia,CHEN Yu-Bo,FANG Hong-Liang,LIU Shuo,TENG Wei-Li,et al.

Acta Agron Sin. 2010, 36(4):  549-554.  doi:10.3724/SP.J.1006.2010.00549

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Soybean mosaic virus (SMV) is a prevalent viral pathogen of soybean. The soybean mosaic virus N3 (SMV3) is the most toxic strain in Northeast China. Soybean lines ICGR95-5117 and ICGR95-5383 with high resistance to SMV3, which were all derived from ICGR661, are recently released from Chinese Academy of Agricultural Sciences. Several genes resistant to soybean mosaic virus have been identified and mapped on different soybean linkage groups by molecular markers. The resistance gene in ICGR95-5383 has been mapped on soybean linkage group F near Rsv1 gene. A dominant marker developed from the candidate gene of Rsv1 has been reported recently. The purpose of this research was to find the origin of the SMV3 resistance gene in ICGR95-5117 and the relationship of this resistance gene with Rsv1 by analyzing the pedigree. Thirty four SSR markers selected from linkage group F and two markers, SCAR marker (SCN11) tightly linked with resistance gene in ICGR95-5383 and Rsv1-f/r makers co-segregated with resistance gene Rsv1, were used to detect the materials in pedigree of ICGR95-5117. The similarity coefficient of the two lines between ICGR95-5117, ICGR95-5383 and ICGR661 was the highest. All the material except for Mangnolid(F-53)B had SMV3 resistance allele at locus SCN11. Williams82 and ICGR661 had the same allelic variation at Rsv1-f/r locus with ICGR95-5117, revealing that the Rsv1 gene in ICGR95-5117 was inherited from Williams 82 via ICGR661. But ICGR95-5117 had higher resistance than ICGR661, indicating it might inherit different genes from SMV3 resistance parent Ludou4.

Analysis of Viability Affecting on Genetic Integrity in Soybean Germplasm Zhong Huang 18 by AFLP Markers

WANG Dong,ZHANG Zhi-E,CHEN Xiao-Ling,XIN Xia,XIN Ping-Ping,LU Xin-Xiong

Acta Agron Sin. 2010, 36(4):  555-564.  doi:10.3724/SP.J.1006.2010.00555

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Using low temperature genebank is a main way for conserving crop germplasm resources. However, with the extension of storage time, the viability of seeds stored in the genebank will inevitably decline. Therefore, preserved seeds need to be regenerated periodically. In this study, soybean cultivar Zhonghuang 18 was used as a material and aged for different days (0, 112, 154, and 196 d) to obtain four populations G₀-1, G₀-2, G₀-3, and G₀-4. The germination percentages of the four populations were 98.0%, 95.0%, 81.0%, and 79.0%, respectively. These populations were regenerated twice in the field. The first descendant populations were marked as G₁-1, G₁-2, G₁-3, and G₁-4, and the second were marked as G₂-1, G₂-2, G₂-3, and G₂-4, respectively. Population G₀-1 was taken as the control. The genetic variation between the control and treated populations was detected using AFLP marker. Sixty individual seedlings derived from each population were detected by 12 AFLP primer combinations. The result showed that t-test probability values for allele frequencies were 1.00 between the control and treated populations, which indicated that there was no significant difference in the allele frequencies of the treated population compared with the control. The genetic similarity coefficient between population G₂-4 and G₀-1 was 0.9333, which manifested high genetic similarity between these two populations. The results of t-test showed that there was no significant difference in effective number of alleles per loci (Ae), index of genetic diversity (He), Shannon’s information index (I) between the control G₀-1 and G₁-1, G₂-1, G₁-2, and G₂-2. The index values of Ae, He,and I for the populations of G₀-3, G₀-4, G₁-3, G₁-4, G₂-3, and G₂-4 declined significantly compared with those of the control G₀-1. The number of rare alleles for the populations G₁-1, G₂-1, G₁-2, and G₂-2 did not change significantly compared with that for the control G₀-1 while that for populations of G₀-3, G₀-4, G₁-3, G₁-4, G₂-3, and G₂-4 declined greatly. Above results showed that the genetic diversity and the number of rare alleles for the descendant population of the populations with 98.0% and 95.0% germination percentages did not change significantly compared with those for the control G₀-1, but declined significantly for the populations with 81.0% and 79.0% germination percentages. Therefore, the viability decline had a greater impact on the genetic composition of soybean population than the regeneration times. It was recommended that soybean seeds with initial germination percentage of 98.0% should be regenerated before its germination percentage declined to 81.0%.

Identification of Mutants from Adzuki Bean (Vigna angularisi) Jingnong 6 seed Induced by Physical and Chemical Agents

TONG Xing,ZHAO Bo,JING Wen-Lin,ZENG Chao-Wu,LIU Hong-Xia,WU Bao-Mei,PU Shao-Jing

Acta Agron Sin. 2010, 36(4):  565-573.  doi:10.3724/SP.J.1006.2010.00565

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Mutational approaches have been widely exploited in breeding, genetics and gene function researches. We firstly developed a large collection of mutants from adzuki bean (Vigna angularisi) cultivar Jingnong 6 treated by 0.5%, 0.9%, and 1.4% EMS for 12 h and 24 h, 400 Gy ⁶⁰Co-γ ray and 100 Gy, 300 Gy, and 600 Gy electron beam. The results indicated that the maximum mutantions were induced by 0.5% or 0.9% EMS for 24 h. More seed color mutants including cream-colored and light red seeds, pod color mutants such as brown, dark brown and black pods were produced by o.5% EMS. Needle leaf, sword, kidney-shaped and small heart-shaped leaf mutants were obtained by 0.9% EMS treatment. The percentage of mutants with 100, 300, and 600 Gy electron beam treatment were 4.09%, 3.64%, and 2.22% respectively. The percentage of mutants treated by 400 Gy ⁶⁰Co-γ ray was 7.23%. Nine hundred thirty-seven EMS-induced M₃ lines and nine hundred thirty-four M₂ lines radiated by ⁶⁰Co-γ ray and electron beam were generated. A total of 1 490 mutants were collected. Mutations included in plant height, plant architecture, leaf shape and color, leaf size, seed shape and color, seed size, pod color, branching type and number, bushy leaf or branch, sprawl, definite growth, sterile, early and late mature, flowering time. The mutant populations are very useful to genetic analysis of gene, gene mapping and cloning, and further the research on functional genomics. These mutants will be useful to serve the adzuki bean improvement.

Mining and Identification of SNP from EST Sequences and Convertion of CAPS Markers in Soybean

SHU Yong-Jun,LI Yong,WU Na-La-Hu,BAI Xi,CAI Hua,JI Wei,ZHU Yan-Ming

Acta Agron Sin. 2010, 36(4):  574-579.  doi:10.3724/SP.J.1006.2010.00574

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SNPs widely distribute throughout genomes from non-coding regions to coding regions, constituting the most abundant molecular markers used in animal and plant genetic breeding. With the rapidly growing genome sequencing projects, a large amount of genomic and EST sequences has become available to the public. Many SNPs are identified by comparing genome sequences or ESTs obtained from genetically diverse lines or individuals in plants. However the SNP assay always relies on expensive equipments or reagent, which has limited the application of SNPs in genetics and breeding especially in plants. The CAPS marker, also known as PCR-RFLP marker, is the technique combining PCR and restriction enzymes digestion to detect the restriction fragment length polymorphisms. With the development of high-throughput sequencing technology, more and more SNPs are identified, among them many mutations have altered the restriction enzymes recognition sites. This provides an opportunity for high-through development of CAPS markers. With soybean genome sequences becoming available, high-throughput SNP marker development will significantly improve genetic mapping, map based cloning in soybean. To discover new SNPs in soybean, we aligned the ESTs with whole genome sequences in different soybean varieties and identified 537 EST-SNPs. The function of genes targeted by these EST-SNPs was analysed, the results showed that these genes participated in subcellular localization, protein binding or catalyzing, metabolic process and cell rescue, defense and disease resistance, etc. Most of these functions are involving in various physiological and biochemical processes influencing important agronomic traits. To develop easy assay method for these EST-SNPs, we identified the EST-SNPs which alter the restrict enzyme recognition sites by software EMBOSS, and 48 pair primers were designed to detect these EST-SNPs. forty-four pair primers amplified single bands (400–800 bp) from genomic DNA of Suinong 14 widely planted in the Northeast China. To verify the SNP polymorphisms, we used these primer pairs for PCR amplification from genomic DNA of Suinong 14, Hefeng 25, Acher, Evans, Peking, PI209332, Guxin wild soybean, Kefeng 1, Nannong 1138-2 and pool DNA of the nine soybean varieties. The PCR amplicons were sequenced, the traces of the 36 discordant ones were detected as candidate SNPs, which were then validated by re-sequencing the individuals. SNPs were identified using restriction enzymess of 26 pair primers with unequivocal restriction pattern were identified as CAPS markers. The SNPs discovery and CAPS markers conversion system developed in this study is fast, low cost and effecient, and holds great promise for molecular assisted breeding of soybean. , and the product

Cloning, Chromosomal Location, and Evolutionary Analysis of α-gliadin Genes from Aegilops tauschii and Common Wheat (Triticum aestivum L.)

ZHU Xi-Ping,LI Xin,LI Ya-Xuan,YAN Yue-Ming

Acta Agron Sin. 2010, 36(4):  580-589.  doi:10.3724/SP.J.1006.2010.00580

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Seven novel α-gliadin genes from common wheat cultivars (Yumai 34 and Yannong 19) andAegilops tauschii accessions (T9, T197, T48, T176, and T17) were amplified and cloned by using a PCR-based strategy. They were designated as Gli-YM34, Gli-YN19, Gli-T9, Gli-T197, Gli-T48, Gli-T176, and Gli-T17, respectively. Their length of the open reading frame (ORF) ranged from 846 to 891 bp, encoding the putative proteins of 282–297 amino acid residues. Comparative analysis showed that all genes isolated had typical structural characters of α-gliadin genes reported previously. Particularly, Gli-YM34 and Gli-YN19 α-gliadins from common wheat possessed an additional cysteine residue, suggesting a possible positive effect on dough quality. Both genes were assigned to Gli-D2 locus on the chromosome 6D by the analysis of four celiac disease toxic epitopes and glutamine residues in the polyglutamine domain as well as nullisomic-tetrasomic lines of Chinese Spring. A total of twenty-one single nucleotide polymorphisms (SNPs) and a 9 bp deletion among the four typical α-gliadin genes were identified. Phylogenetic and evolutionary analysis revealed that the α-gliadin genes are closely related to LMW-GS genes and their divergence occurred 43.69 million year ago. Less homology was found between α-gliadin genes and HMW-GS and ω-gliadin genes, and they diverged about 79.39 million year.

Inheritance and QTL Mapping of Waterlogging Tolerance at Seedling Stage of Soybean

SUN Hui-Min,ZHAO Tuan-Jie,GAI Jun-Yi

Acta Agron Sin. 2010, 36(4):  590-595.  doi:10.3724/SP.J.1006.2010.00590

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Flooding is a serious problem for soybean production in eastern and southern China. Development of cultivars with tolerance to waterlogging is one of the effective ways to cope with the stress problem. For which, the genetic knowledge of waterlogging tolerance is of essential importance. The present study was aimed at revealing the inheritance and mapping the QTLs for waterlogging tolerance of soybean at seedling stage. The materials used were 175 recombinant inbred lines (RILs) derived from the cross Su88-M21 (Tolerant) × Xinyixiaoheidou (Highly sensitive), designated as NJRISX. A pot experiment was held under 5–7 cm waterlogging stress for 20 days at V2 stage. Based on the correlation and principal component analysis of eight traits, we calculated the joint waterlogging tolerance index from the average of individual tolerance index of plant height increment, number of leaves at the end of waterlogging and plant height at maturity to evaluate the tolerances of the materials. There existed obvious transgressive segregation and significant differences among the RIL lines. The segregation analysis under major gene plus polygene mixed inheritance model showed that waterlogging tolerance of soybean was controlled by two linked major genes plus polygenes with major gene heritability of 62.83% and polygene heritability of 8.90%. By using composite interval mapping (CIM) and multiple interval mapping (MIM) of WinQTL Cartographer Version 2.5, two QTLs conferring waterlogging tolerance were mapped in the marker regions of Satt229–Satt527 and Satt527–satt286 on linkage groups L2, explaining 11.76% and 12.34% of the total phenotypic variation, respectively. Accordingly, the results from segregation analysis and QTL mapping are relatively consistent in NJRISX population.

Construction and Transformation of RNAi Vector of MsZFN Gene from Alfalfa (Medicago sativa L.)

QIN Zhi-Hui1,2,CHAO Yue-Hui1,YANG Qing-Chuan1,*,KANG Jun-Mei1,SUN Yan3,WANG Ping

Acta Agron Sin. 2010, 36(4):  596-601.  doi:10.3724/SP.J.1006.2010.00596

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Based on the sequence of Medicago sativa Zinc Finger Protein (MsZFN) gene (GenBank accession No. EU624138), two pairs of specific primers containing different enzyme sites were designed. With the template of full-length cDNA , positive-sense strand and antisense strand were obtained, which were separately inserted into the expression vector pART27. The RNAi vector pART-F-R containing a hairpin structure was constructed. Mediated by Agrobacterium tumefaciens, pART-F-R was transformed into alfalfas. PCR testing showed that three transgenic plants were obtained. Result of RT-PCR showed that transgenic alfalfas had lower expression level of MsZFN gene than wild alfalfas. Those results indicated that the RNAi vector pART-F-R containing a hairpin structure was constructed successfully and highly efficient for the simultaneous silence of MsZFN gene.

QTL Analysis of the Photoperiod Sensitivity-Related Traits at Different Developmental Stages in Maize(Zea mays L.)

KU Li-Xia,SUN Zhao-Hui,WANG Cui-Ling,ZHANG Jun,ZHANG Wei-Qiang,CHEN Yan-Hui

Acta Agron Sin. 2010, 36(4):  602-611.  doi:10.3724/SP.J.1006.2010.00602

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Maize is originally a short-day species and most tropical materials remain highly sensitive to photoperiod. Photoperiod sensitivity limits the potential for successful exchange of germplasm across temperate-tropical regions. Therefore, it would be very useful for breeders to better investigate the genetic basis of photoperiod sensitivity due to not only being benificial to expansion, improvement and innovation of germplasm but also enhancing adaptation of maize varieties to seasonal changes in the length of a day (photoperiod). For identifying the genetic controls underlying this adaptation at different development stages in maize, a set of 207 recombinant inbred lines derived from a temperate and a tropical inbred line cross was evaluated for leaf number and seedling or plant height at different developmental stages in a long-day environment. The results showed there was apparent difference in the average of leaf number and plant height for two parents. Leaf number and seedling height of the parent CML288 were less than those of Huangzao 4 at the beginning of plant development tested, but were more than those of Huangzao 4 at the later developmental stages. There was significant difference in the traits at the tested developmental stages for F₇ recombinant inbred lines. The unconditional and conditional QTLs for these traits were detected using genetic linkage maps constructed by 237 SSR markers with a total length of 1753.6 cM and an average space between two markers of 7.4 cM, and composite interval mapping (CIM). Eleven and twenty QTLs were detected for leaf number and plant height, respectively. But there was no effect of conditional QTL at all the tested developmental stages. The conditional and unconditional QTLs for leaf number and plant or seedling height were mapped on chromosomes 1, 9 and 10. Especially, the QTLs located on chromosome 10 (near to umc1873) were for two traits at the later developmental stages, accounting for 4.34–25.74% and 10.02–22.75% of total phenotypic variation by single conditional and unconditional QTL, respectively. These results showed that these regions might encompass some crucial candidate genes controlling photoperiod sensitivity.

Construction of Protein Two-Dimensional Polyacrylamide Gel Electrophoresis System for Brassica napus

GAN Lu,LI Dian-Rong,ZANG Xin,FU Chun-Hua,YU Long-Jiang,LI Mao-Teng

Acta Agron Sin. 2010, 36(4):  612-619.  doi:10.3724/SP.J.1006.2010.00612

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Two-dimensional polyacrylamide gel electrophoresis has been widely applied in proteomic researches. The approach can analyze dynamic changes of proteomics of biological samples under different conditions to identify specific proteins and genes. The two-dimensional gel systems for rice, Arabidopsis and other species have been established. The purpose of this research was to establish a suitable system for B. napus to analyze proteomics. Rapeseed variety of 08127 was used in the experiment, the proteins were obtained by the trichloroacetic extraction method with pH 4–7 gel brands under the improved IEF procedure, showing a clean two-dimensional electrophoresis map, so a proper system for B. napus wasformed. Then the system was validated by using the young seedlings, leaves and stems from other varieties, and the same results as those from variety 08127 were obtained. The proteomics profiling of seedlings in different ages of B. napus was analyzed by using the previous established protocol, we found 20 up-regulated and 51 down-regulated proteins with more than two times changes in 30 days old B. napus stems compared with in 15 days old B. napus stems and some of the different protein spots were successfully identified. The system established in this study is useful for B. napus proteomic research in the future.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

System Design of Free Air Temperature Increased (FATI) for Field Nighttime Warming Experiment and Its Effects on Rice-Wheat Cropping System

ZHANG Bin,ZHENG Jian-Chu,TIAN Yun-Lu,DONG Wen-Jun,CHEN Jin,YANG Fei,ZHANG Wei-Ji

Acta Agron Sin. 2010, 36(4):  620-628.  doi:10.3724/SP.J.1006.2010.00620

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There is evident asymmetry in climate warming between daytime and nighttime with the highest warming rate occurring at nighttime. Since there are high uncertainties in the projecting of climate warming effects on crop production using crop models, it is essential to design a reliable field warming system to study the responses of crop production system to nighttime warming in field. Therefore, based on existing field warming facilities in the world, we designed a rice-wheat warming system in Nanjing, Jiangsu province, the first facility of Free Air Temperature Increased (FATI) for crop production in China, to study the effects of nighttime warming on crop growing duration and yields during 2006–2009. The results showed that the warming effect of this facility was significant and well-distributed within 2 m × 2 m area. In sunny, rainy and cloudy days, the night temperatures on the field surface within the 4 m² warming area were increased by 2.4℃, 2.3℃, 2.1℃ on average on the tested turfgrass land. At the vertical dimension, the night temperatures of 5 cm underground, ground surface, 40 cm aboveground, and 90 cm aboveground were enhanced by 1.2℃, 2.3℃, 0.7℃, 2.2℃ on average. In the rice growing period, the night temperatures of 5 cm underground, field surface, the middle part of crop community and the canopy were 0.7℃, 0.6℃, 1.0℃, and 1.6℃ higher compared to the un-warming plots, respectively. In the winter-wheat growing period, the increments were 1.2℃, 1.5℃, 1.8℃, and 1.9℃, respectively. During the whole crop growing period, the trends of diurnal change of the above temperatures in warming plots were all similar with those in the un-warming plots. The distributed characteristics of soil moisture in wheat field were not significantly changed under this warming facility but with a slightly decreasing trend. The decrements of soil moisture in the 0–25 cm soil layers were all within the scale of 0.99–1.62 percentage points with no significant difference compared to the un-warming control. Under this warming facility, rice and wheat growing stages were significantly changed, and the durations of rice and wheat from the sowing date to the initial heading date were shortened by 2.5 d and 11.5 d respectively. Nighttime warming reduced rice yield by 4.51%, but increased wheat yield by 18.30% on average. Although, there existed significant differences in the warming rates among different stages of crop growing byusing the warming facility, evident seasonal discrepancy of warming rates also often occurred in the real fields under climate warming situation. Therefore, the above results suggest that this night warming facility meets with the temperature characteristics of climate warming and can be used for studies on the responses of crop production system to nighttime warming.

Relation between Light Qualities and Accumulation of Steroidal Glycoalkaloids as Well as Signal Molecule in Cell in Potato Tubers

WANG Wang-Tian,JI Yan-Lin,ZHANG Jin-Wen,TAO Shi-Heng,Wang Di,WU Bing

Acta Agron Sin. 2010, 36(4):  629-635.  doi:10.3724/SP.J.1006.2010.00629

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The potato steroidal glycoalkaloids (SGAs) are secondary metabolites, two major SGA in cultivated potato (Solanum tuberosum) are a-chaconine and a-solanine, and their total content in tubers should not exceed the safety limit of 20 mg per 100 g fresh weight, otherwise it can be toxic to humans. Accumulation of SGAs in potato tubers is influenced by many factors including the key environmental factors, temperature and light. In order to reduce the content of SGAs and research the accumulation mechanism of SGAs in potato tubers，in the present study we attempted to compare the contents of SGAs, second messengers—calmodulin and the G protein in potato tubers, treated with the treatments of red light, blue light, white light and darkness under the same temperature(15℃). The results indicated that red light significantly (P < 0.01) increased the average content of SGAs in potato tubers,with 26.02%, 55.50%, and 100.79% higher than that treated with blue light, white light and darkness, respectively. It was confirmed that light with different wavelengths has different effects on accumulation of SGAs in potato tubers. Among factors influencing the accumulation of SGAs in potato tubers, the red light took the first place and the blue light took the second place. Meanwhile, the content of second messengers－the G protein in potato tubers treated with red light was 0.95%, 2.01%, and 3.86% higher than that treated with blue light, white light and darkness, respectively. And the content of calmodulin in potato tubers treated with red light was 7.94%, 37.41%, and 87.24% higher than that treated with blue light, white light and darkness, respectively. It was inferred that the red light is the signal molecule for SGAs accumulation, which stimulates the acceptor (PHYB) of red light and participate in accumulation of SGAs in potato tubers, together with the second messenger G protein, calmodulin, and so on.

Heat Shock Protein 70 May Improve the Ability of Antioxidant Defense Induced by the Combination of Drought and Heat in Maize Leaves

HU Xiu-Li,LI Yan-Hui,YANG Hai-Rong,LIU Qun-Jun,LI Chao-Hai

Acta Agron Sin. 2010, 36(4):  636-644.  doi:10.3724/SP.J.1006.2010.00636

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In order to determine the mechanism of heat shock protein (HSP70) increasing crops endurance to the combination of drought and heat, we investigated the physiological characteristics of four maize varieties with different responses to drought and heat stresses. The results are as follows: (1) Under drought, heat, the combination of drought and heat, the increase of malondialdelehyde (MDA) content in leaf was the lowest in Zhuyu 309 without endurance to three stresses and the highest in Longyu 602 with endurance to three stresses; under drought, leaf MDA increase in Zhengdan958 with drought-endurance was less than that in Xundan 20 leaves with heat-endurance; under heat, leaf MDA increase was more in Zhengdan 958 than in Xundan20. (2) In Zhengdan958, Xundan20, Longyu602 leaves, the increase of ascorbate peroxidese (APX), glutathione reductase (GR), superoxide dismutase (SOD), catalase (CAT) activities was more than that in Zhuyu 309 leaves under drought, heat, the combination of drought and heat; under drought, APX, GR, SOD, CAT activities of Zhengdan 958 leaves increased significantly more than those of Xundan 20’, but those were contrary under heat; under the combination of drought and heat, APX, GR, SOD activities of Longyu 602 leaves increased significantly more than those of Zhengdan 958 and Xundan 20. (3) The pretreatment with HSP70 inhibitor quercetin (Q) significantly inhibited the increase of antioxidant enzymes activities in leaves of 4 maize varieties exposed to the three stresses. These results suggested that HSP70 involved in the increase of antioxidant enzyme activity in leaves of 4 maize varieties exposed to drought, heat and their combination, and APX, GR, SOD activities could be used as chemical and biological indicators to evaluate the crop endurance to drought, heat, and the combination of drought and heat stresses.

Characteristics of Leaf Senescence in Rice Genotypes with Different Nitrogen Use Efficiencies

WEI Hai-Yan,ZHANG Hong-Cheng,MA Qun,DAI Qi-Gen,HUO Zhong-Yang, et al.

Acta Agron Sin. 2010, 36(4):  645-654.  doi:10.3724/SP.J.1006.2010.00645

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Although excessive use of N fertilizer can result in the rapid decrease of N use efficiency and other serious environment problems, N fertilizer is yet the most important and largest input in modern rice production. Previous researches have been demonstrated that variation in N use efficiency existed among rice genotypes. Therefore, it is of urgent importance to elucidate the physiological mechanism of rice N absorption and utilization for increasing N use efficiency. In this research, field experiment with 225 kg ha^-1 N fertilizer application was carried out in 2006 on the farm of Yangzhou University, Jiangsu province, China. Twelve rice genotypes (six N efficient and six N inefficient) selected from one hundred and twenty rice cultivars grown in Yangzhou during 2004 and 2005 were adopted to investigate the characteristics of N absorption and accumulation. Compared with N inefficient genotypes, N efficient genotypes had more obvious advantages in N absorption rate, the amount and the percentage of N accumulation during the growth phases from elongating to heading and from heading to maturing. And of which the advantage during the growth phase from heading to maturing was particularly significant. Since rice organs aged and the plant physiological functions declined gradually from heading to maturing, the characteristics of rice senescence was then studied to understand the relationships between rice senescence and the N absorption and accumulation, and the N use efficiency. Results showed that, during the period of grain filling, the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in flag leaf of N efficient genotypes were obviously higher than those of N inefficient genotypes. Contrarily, content of malondialdehyde (MDA), which is the product of membrane lipid peroxidation, was lower in N efficient genotypes than in N inefficient genotypes significantly. After the stage of full heading, N use efficiency was positively correlated to the activities of SOD, POD, and CAT in flag leaf of rice and negatively correlated to the content of MDA. So it reveals that, at late growth stages of rice, the activities of SOD, POD, and CAT of N efficient genotypes were higher than those of N inefficient genotypes in flag leaves, which could eliminate reactive oxygen species, inhibit the membrane lipid peroxidation and decrease the content of MDA more efficiently in N efficient rice genotypes. Therefore, compared with the N inefficient genotypes, the leaf senescence of N efficient genotypes was relatively slower, which could prolong the functional period of leaves, enhance the organic matter accumulation and improve the efficiency of N absorption and utilization.

Effects of Water-Nitrogen Interaction on Absorption，Translocation and Distribution of Nitrogen,Phosphorus,and Potassium in Rice

SUN Yong-Jian,SUN Yuan-Yuan,LI Xu-Yi,ZHANG Rong-Ping,GUO Xiang,MA Jun

Acta Agron Sin. 2010, 36(4):  655-664.  doi:10.3724/SP.J.1006.2010.00655

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Hybrid rice Gangyou 527 was used to investigate the effects of three irrigation regimes (submerged irrigation, W₁; dry cultivation, W₃; and damp irrigation before booting stage plus shallow irrigation at booting stage plus wetting-drying alternation irrigation from heading stage to mature stage, W₂) and different amounts of nitrogen (N) application on absorption, transport and distribution of N, phosphorus (P), and potassium (K) in rice, and study on correlations of N, P and K absorption characteristics and its relationship with grain yield. The results showed that there was an obvious interaction between irrigation regime and among ofN application. Correlation analysis indicated that there existed significantly or highly significantly positive correlations between the amounts of N, P and K absorption, transfer, distribution, and between each of them and yield under water-nitrogeninteraction at the mainly growth stages, and there existed highly significantly positive correlations between yield and the accumulations of N, P before heading stage and the amount of K absorption at tillering stage. Combining N, P and K absorption characteristics and its relationship with grain yield performance, W₂ with suitable N application amount (N₁₈₀) was the best model in this paper referred as the water-nitrogen coupling management model, optimum N application amount was 180 kg ha^-1 forsubmerged irrigation, and 90–180 kg ha^-1 for dry cultivation conditions.

Effects of Different Levels of Boron Fertilizer on Alfalfa Photosynthesis and Source-Sink Translocation of Soluble Carbohydrate

ZONG Yu-Zheng,WANG Wen-Yue,HAN Qing-Fang*,DING Rui-Xia,JIA Zhi-Kuan,NIE Jun-Feng

Acta Agron Sin. 2010, 36(4):  665-672.  doi:10.3724/SP.J.1006.2010.00665

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Alfalfa, one of the uppermost leguminous grasses in the world, is widely cultivated in arid-semiarid areas of the loess plateau. Because the content of water-soluble Boron (B) is less than 0.5 mg kg^–1 in 56% soil in loess plateau and alfalfa is a highly sensitive crop to B, it is necessary to supply adequate B for perennial alfalfa growth. Previous studies showed that physiological characteristics of crops were influenced by B through its effect on the structure of chloroplast, promoting the transportation of sugar and adjusting the balance between moisture and nutrient, then indirectly on the oxidation and reduction process of photosynthesis and respiration of crops. Until now, most studies have concentrated on the effects of B on yield and quality of alfalfa, few reports on the impact of B on photosynthetic characteristics of alfalfa were available. This study focused on the effects of different B fertilizer levels on the photosynthesis and translocation of soluble carbohydrate by spraying B on the leaves surface of alfalfa grown in B deficient soil, and investigated the high-yield technology of applying B fertilizer in alfalfa. The results showed that photosynthesis and translocation of soluble carbohydrate between source and sink were differently influenced by spraying five concentrations of B fertilizer with different times (1, 2, or 3 times) at reviving, branching and early flower bud stages. Significant influences were observed on the increase of P_n, T_r, and chlorophyll content by 39%, 30%, and 70%, respectively, in the treatment of spaying three times of 0.3% borax solution compared with the control. Leaf area increased by 37% and soluble carbohydrate concentration in leaves decreased by 50% in the treatment of spraying three times of 0.2% borax solution. B content, P_n, and T_r in leaf were significantly increased by 51%, 33%, and 25%, respectively in the treatment of spraying two times of 0.4% borax solution compared with the control. However, B intoxication might occur, along with the decrease of photosynthesis capacity and retardness of growth by spraying 0.5% borax solution 1–3 times.

Effect of Shading at Post Flowering on Photosynthetic Characteristics of Flag Leaf and Reponse of Grain Yield and Quality to Shading in Wheat

GUO Cui-Hua,GAO Zhi-Qiang,MIAO Guo-Yuan

Acta Agron Sin. 2010, 36(4):  673-679.  doi:10.3724/SP.J.1006.2010.00673

Abstract ( 3104 )   PDF (478KB) ( 2010 )   Save

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Shading post flowering, caused by cloudy weather and the surrounding protective trees, often occurs in some wheat (Triticum aestivum L.) area in north China. In general, wheat yield is negatively influenced by shading post flowering, but the effect on grain quality is reported discrepantly. This study aimed at disclosing the effects of post-flowering shading on photosynthesis of leaf and yield and quality of grain in wheat, accordingly, giving suggestions to wheat production. Three treatments were designed with shading of 20%, 50%, and 80% for 30 d, respectively. The normal condition was taken as the control. The results showed that shading treatments had significant influences on photosynthetic characteristics of flag leaf. The shading treatments increased the number of sterile spikelet and reduced the grain weight per spike and the 1000-grain weight. As a result, the grain yield of the three shading treatments significantly decreased by 27.6%, 49.0%, and 60.2% compared with the control. In the shading treatments, the contents of the chlorophylls a and b increased, whereas the ratio of chlorophyll a to chlorophyll b decreased. Moreover, the net photosynthetic rate, the stomatal conductance, and the transpiration rate were also significantly reduced, but the intercellular CO₂ concentration was promoted. The shading depression on net photosynthetic rate became smaller in the process of grain filling, with the largest effect at early stage of grain filling and the smallest effect at late stage of grain filling stage. The contents of protein, wet gluten, glutenin, gliadin and the ratio of glutenin to gliadin in grains increased significantly with the increase of shading. The shading influence on glutenin was greater than that on gliadin. Although the shading treatments decreased grain yield obviously, it raised some quality parameters, such as extensibility, development time, stability time, and water absorption of dough. The responses of yield and quality of wheat grain to shading were different because of the discrepant synthesis mechanisms of starch and protein under weak light condition. In wheat protective areas, yield is a priority factor and the tree-wheat intercropping mode should be avoided.

RESEARCH ACTIVITIES

Genetic Analysis for Lysine Content of Rapeseed Cake (Brassic napus L.) at Different Periods after Anthesis

CHEN Guo-Lin,WU Jian-Guo,ZHANG Li,SHI Chun-Hai

Acta Agron Sin. 2010, 36(4):  680-687.  doi:10.3724/SP.J.1006.2010.00680

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Both conditional and unconditional analysis methods were applied to estimate the genetic main effects and the genotype × environment (GE) interaction effects from embryo (cotyledon), cytoplasmic and maternal plant at different periods after anthesis for lysine content of rapeseed cake by using two-year experimental data. Lysine content (LC) in rapeseed cake was simultaneously controlled by the genetic main effects and their GE interaction effects from different genetic systems, especially for the GE interaction effects. Therefore, the expression of genes conferring LC in the different genetic systems could be significantly influenced by the environments. Among the different genetic components, the maternal effects on LC of rapeseed cake were the most important at all periods after anthesis except for the larger embryo main effects at 36 day after flowering, in which both maternal dominance effect and maternal additive interaction effect were more visible. It was found that the new expression of quantitative genes on LC trait was most active at 23–29 days after flowering by using the conditional statistical analysis method. The discontinuity of gene expression in the developmental process of rapeseed was also observed. The total narrow-sense heritability of LC was high, of which the maternal heritability was important at most periods after anthesis. It was suggested that LC could be efficiently improved when selection is based on the holistic performance of maternal plants in generations. The study further suggested that Eyouchangjia and Gaoyou 605 were better than other parents for increasing LC of progenies.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Whole-Genome Sequence Characterization of Primary Auxin-Responsive Aux/IAA Gene Family in Sorghum (Sorghum bicolor L.)

WANG Yi-Jun,Lü Yan-Ping,XIE Qin,DENG De-Xiang,BIAN Yun-Long

Acta Agron Sin. 2010, 36(4):  688-694.  doi:10.3724/SP.J.1006.2010.00688

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The phytohormone auxin plays an important role in organism growth, development and differentiation. Membersof Aux/IAA gene family are responsive primarily to auxin induction. Despite the physiological importance, sequence characterization of Aux/IAA genes has not yet been reported in sorghum. Herein, we presented the isolation and characterization of Aux/IAA genes from sorghum using bioinformatic method. A total of 25 Aux/IAA gene family members were distributed on nine chromosomes in sorghum except chr. 6. Sequence alignment and phylogenetic analysis showed major sorghum Aux/IAA proteins shared four conserved domains. There were nineteen pairs of sorghum / maize and two pairs of sorghum / rice Aux/IAA proteins which were in the same clades of the dendrogram. Aux/IAA proteins partly demonstrated in maize is the closest relative of sorghum in the grass family. The results will be helpful to the auxin signal transduction cascade investigation and gene family research in other crops.

RESEARCH ACTIVITIES

Relationship between Quality Traits of Soft Red Winter Wheat and Cookie Diameter

YAO Jin-Bao,Edward SOUZA,MA Hong-Xiang,ZHANG Ping-Ping,YAO Guo-Cai,YANG Xue-Ming

Acta Agron Sin. 2010, 36(4):  695-700.  doi:10.3724/SP.J.1006.2010.00695

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Fifty-seven soft red winter wheat (Triticum aestivum L.) genotypes including two cultivars released in Jiangsu Province and 55 advanced lines were subjected to quality tests of sixteen parameters, such as solvent retention capacity (SRC) and RVA viscosity parameters. The results showed that there were great variations among wheat genotypes for quality traits and cookie diameter. Significant correlations were observed between cookie diameter and 1000-kernel weight (r = -0.3910, P < 0.01), flour yield (r = 0.5548, P < 0.01), flour protein (r = -0.3032, P < 0.05), flour particle size (r = -0.5667, P < 0.01), water SRC (r = -0.8579, P < 0.01), carbonate SRC (r = -0.8643, P < 0.01), lactic acid SRC (r = -0.6120, P < 0.01), sucrose SRC (r = -0.7566, P < 0.01), breakdown (r = 0.4337, P < 0.01), peak time (r = -0.2702, P < 0.05), and pasting temperature (r = -0.6158, P < 0.01). According to the cluster analysis, the 57 genotypes were classified into three groups and several subgroups. The cookie diameter of the three groups was 16.75, 15.14, and 18.45 cm. A total of nine lines were screened out with higher cookie diameter than Ningmai 9. These lines are recommended in soft wheat breeding program.

Photosynthetic Activity and Its Correlation with Matter Production in Non-foliar Green Organs of Cotton

ZHANG Ya-Li,FENG Guo-Yi,HU Yuan-Yuan,YAO Yan-Di,ZHANG Wang-Feng

Acta Agron Sin. 2010, 36(4):  701-708.  doi:10.3724/SP.J.1006.2010.00701

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In addition to the green leaves, commonly considered as the primary sources of photosynthate production, higher plants can potentially use almost all vegetative and reproductive structures to perform photosynthetic CO₂ assimilation. Study on photosynthetic activity of the different green organs is of great significance to develop the potential of photosynthesis of the whole plant. The green organs in cotton (Gossypium hirsutum L.) consist of leaf and non-foliar organs including bract, boll, and stem. Field experiments were conducted to evaluate the chlorophyll content, chlorophyll fluorescence, electron transport of photosynthetic apparatus and canopy photosynthesis rate, and the correlation of photosynthetic activity with matter production in different green organs of cotton. Three super high-yielding hybrid cotton cultivars, Lumianyan 25, Xinluzao 43, and Shiza 2, and two traditional cotton cultivars, Xinluzao 13 and Xinluzao 33, were grown with Under-Mulch-Drip irrigation in Xinjiang province. The results revealed that both the chlorophyll content and actual quantum yield of PS II were higher in leaf, followed by boll, bract and stem. Compared to traditional cotton, both hybrid cotton cultivars had higher actual quantum yield of PS II in boll and stem, whereas no differences were observed on leaf and bract. As expected, higher canopy photosynthesis rate was presented in non-foliar green organs of high-yielding hybrid cotton. Furthermore, there were significant correlations of dry matter production with adaptability of high-light and faster restoration after photoinhibition in non-foliar green organs of high-yielding hybrid cotton.

Observation and Analysis of Meiotic Behaviors of Pollen-Mother-Cell in Sorghum A₆ Cytoplasmic Male Sterile Line

LIANG Xiao-Hong,YI Zhi-Ben,DENG Xiao-Min,XIE Xiao-Li

Acta Agron Sin. 2010, 36(4):  709-712.  doi:10.3724/SP.J.1006.2010.00709

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Sorghum (Sorghum bicolor L. Moench) is one of the most important food crops in the world, and it is also one of the earliest crops, which the heterosis has been commercially used due to the discovery and utilization of cytoplasmic sterility (CMS). There are seven types of CMS in sorghum, including A₁, A₂, A₃, A₄, A₅, A₆, and 9E. In this study, A₆ cytplasmic male sterile line A₆ Tx398 and its isogonic maintainer line B₆ Tx398 were used to observe and analyze the chromosomal behaviors of A₆ CMS during the microsporic meiosis. Compared with maintainer line B₆ Tx398, the abnormal chromosomal behaviors were not observed under biologic photomicroscope until the diplotene in prophase I. From then on to the tetrad formation, various abnormal chromosomal behaviors were found within the pollen mother cells (PMCs): compared with its B₆ line in most of the PMCs in prophase I, the number of homologous chromosomes was twice (2n=40) that of its isogenic line (2n=20), i.e. 20 pairs of homologs in a cell. In anaphase I, some homologs became lagged or even not divided and stayed near the equatorial plane. Cytoplasm of most PMCs did not divide to form a dyad in telophase II, so that in prophase II 40 sister chromosomes presented in a cell, which were arranged ring-like,  dispersed or X-like. In telophase II, two, three or four chromosomal groups were found in a cell. Some PMCs divided into triad other than tetrad with unequal number of chromosomes in each monad. The disorders of chromosomal behaviors during the pollen mother cell meiosis of A₆ CMS made the incompletion of the normal meiotic process, leading to the abortion of microsporogenesis and development.