Table of Content

12 April 2011, Volume 37 Issue 04

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

GmCHS8 and GmIFS2 Gene Co-Determine Accumulation of Isoflavonoid in Soybean

YI Jin-Xin, XU Zhao-Long, WANG Jun-Feng, ZHANG Da-Yong, HE Xiao-Lan, ZULFIQAR Ali, ZHU Hong-Run, MA Hong-Xiang, SANGEETA Dhaubhade

Acta Agron Sin. 2011, 37(04):  571-578.  doi:10.3724/SP.J.1006.2011.00571

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Soybean isoflavonoids (isoFLVs) are natural secondary compondsproduced in Phenylpropanol metabolism Pathway. In past ten years, the isoFLVs were proved with anti-cancer activity to human health and therefore intensively included in nowadays food industry. However, the low content in natural soybean germplasm is a major limit to be weed in desired population. Herein we report that expression patterns of 18 362 genes were monitored by using Microarray between 30 to 70 days after pollination (DAP) during the soybean seed development. The expression profile of CHS8 and IFS2 revealed by both Microarray and RT-PCR indicated these two genes may play critical roles in determination of the accumulation of isoFLV in soybean seeds. According to Agrobacterium rhizogenes transformation system, over-expression of individuals of CHS8 and IFS2 resulted in 65.9% and 34.4% isoFLV increase respectively, but not significant in Duncan’s multiple test at 0.05 probability level. However, co-expression of CHS8+ IFS2 significantly increased (P<0.0001) the isoFLV content up to 82.3% when comparing to non-transgenic control. Conclusively, both IFS2 and CHS8 gene co-determine the accumulation of isoFLV in soybean.

Detection of Interactions between SCR and SRK in Brassica oleracea L. by Yeast Two-Hybrid System

LUO Bing, XUE Li-Yan, SHU Li-Quan, ZHANG He-Cui, PENG Yi-Bei, CHEN Song, YANG Hong, YANG Hun, LI Cheng-Qiong, WANG Xiao-Jia

Acta Agron Sin. 2011, 37(04):  579-586.  doi:10.3724/SP.J.1006.2011.00579

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For further study on mechanism of the mutual recognition between S-locus receptor kinase (SRK) and S-locus Cysteine-rich protein (SCR) in Brassica, the extracellular domains of SRK (named as eSRK) and SCR were amplified by nested PCR using Brassica oleracea L. ‘D3’ with the trait of typical self-incompatibility (SI), and the interactions between eSRK and SCR was detected by the yeast two-hybrid system. Then the full-length eSRK and the SCR were fused to the Gal4 DNA activation domain (designated pGADT7eSRK) and the Gal4 DNA binding domain (designated pGBKT7SCR) by the gene homologous recombination technique respectively. Then the pGADT7eSRK plasmid and the pGBKT7SCR were transformed into the Y187 yeast strain and the Y2HGold yeast strain respectively. The two transformed yeast strains did not exhibit autoactivation. The diploids, which were fused by the transformed Y2HGold yeast strain and the transformed Y187 yeast strain, grew on selective agar plates (SD/–Ade/–His/– Leu/–Trp/X-a-Gal/AbA), and the resulting colonies were blue, which strongly indicated that eSRK and SCR could combine with each other.

Cloning of Cold-Inducible Gene SlCMYB1 and Its Heterologous Expression in Rice

ZHANG Xin, CHENG Zhi-Jun, LIN Qi-Bing, WANG Jiu-Lin, WAN Jian-Min

Acta Agron Sin. 2011, 37(04):  587-594.  doi:10.3724/SP.J.1006.2011.00587

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We isolated a cDNA clone, designated SlCMYB1 (for Solanum lycopersicum Cold MYB 1), from tomato by analyzing the previous microarray data of the low temperature transcriptome of tomato. SlCMYB1 encodes a R2R3-MYB family gene, which contains a conserved DNA-binding domain composed of two repeat motifs. The SlCMYB1-GFP fusion protein was localized to the nucleus in a transient expression assay. Expression of SlCMYB1 was not only strongly induced by cold and salt, but also by dehydration and abscisic acid (ABA). To understand function of SlCMYB1 in crop plants under stress conditions, we generated transgenic plants in rice over-expressing SlCMYB1 under control of the CaMV 35S promoter. Preliminary results showed that overexpression of SlCMYB1 in rice induced constitutive expression of the cold-responsive gene OsP5CS1 and OsWCOR413 and might be conferred enhanced tolerance to cold treatments for non-acclimated transgenic plants, compared with wild type plants. Our data suggest that SlCMYB1 might play an important role in plant responses to cold stress by regulating cold-responsive gene expression and might be a useful gene for improving cold tolerance in crop plants.

Genetic Diversity of Chinese Faba Bean (Vcia faba L.) Germplasm Revealed by ISSR Markers

WANG Hai-Fei, GUAN Jian-Ping, MA Yu, SUN Xue-Lian, ZONG Xu-Xiao

Acta Agron Sin. 2011, 37(04):  595-602.  doi:10.3724/SP.J.1006.2011.00595

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Faba bean is an important world grain legume crop with high seed-protien content. It plays a critical role in crop rotation. China is the largest faba bean producer in the world. However, little is known about the genetic potential of indigenous faba bean germplasm from China. The assessment of genetic diversity in faba bean germplasm is important for its utilization in breeding programs. To evaluate genetic diversity and relationship of faba bean germplasm in China, we characterized a total of 527 accessions of faba bean from autumn and spring sowing regions in China with 11 ISSR primers. There were 278 unambiguous bands generated, 268 of which were polymorphic, with the rate of polymorphic bands of 0.96. Nei’s gene diversity and Shannon’s information index ranged from 0.1267–0.2509 and 0.1932–0.3767, respectively, in different geographic groups. The Inner Mongolia group showed the highest value, followed by the Yunnan and Gansu groups. Accessions from Jiangxi showed lowest diversity. The spring faba bean germplasm was clearly separated from winter faba bean germplasm, based on principal component analysis and UPGMA clustering analysis. Germplasm from Zhejiang and Sichuan was quite distinct from that from other provinces. The results indicated that the genetic relationship and diversity of faba bean in China are closely associated with their growth habit, geographical origin, and ecological distribution.

QTL Identification of Drought Tolerance to Soybean in Selection Population

LI Can-Dong, JIANG Hong-Wei, LIU Chun-Yan, GUO Tai, WANG Zhi-Xin, WU Xiu-Gong, ZHENG Wei, QIU Peng-Cheng, ZHANG Wen-Bo, SONG Ying-Bo, LUAN Yi-Na, CHEN Qiang-Shan, HU Guo-Hua

Acta Agron Sin. 2011, 37(04):  603-611.  doi:10.3724/SP.J.1006.2011.00603

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A primary backcross introgression of soybean population was constructed by using Hongfeng 11 as recurrent parent and Clark as donor parent. After screening under drought stress, the genotypes of selective population were obtained with the whole genome SSR markers, and the frequency of donor genes segments were analyzed. QTLs of five drought-tolerance traits were mapped by Chi-testcombined GGT linkage group analysis. In total, 23 SSR excessive introgression loci on 10 chromosomes were detected with χ²test. The QTL identification was conducted by one-way ANOVA (for single marker analysis, P<0.01). Eight QTLs of RWC (relative water content) were located on A₁, B₁, C₂, E, L, and N linkage groups, nine QTLs of RRL (relative root length) on C₂, F, G, and I linkage groups, 11 QTLs of RRW (relative root dry weight) on A₂, B₁, B₂, E, F, K, L, M, and O linkage groups, 12 QTLs of RGY (relative grain yield) on B₁, D₁a, E, F, G, I, L, M, and O linkage groups and seven QTLs of RMB (relative microbial biomass) on E, F, G, K, L, and N linkage groups. The QTL at Sat_136 on E linkage group was identical for RWC, RRW, RGY, and RMB, and QTL at GMRUBP on F linkage group for RRW and RMB, QTL at Satt586 on F linkage group for RRL, RRW, and RGY, QTL at Satt167 on K linkage group for RRW and RMB, QTL at SOYPRP1 on K linkage group for RRL and RMB, QTL at Satt398 on L linkage group for RRL and RGY, QTL at Satt694 on L linkage group for RWC and RMB, QTL at GMSL514 on L linkage group for RRW and RGY. All above QTLs were coincident with those detected by excessive introgression of χ² test. Thirty-three QTLs were mapped by χ² test or one-way ANOVA, and among them 17 QTLs were detected by both methods. So these QTLs should be essential for drought tolerance. The results provide a foundation for fine mapping, cloning and molecular breeding of favorable genes related with drought tolerance.

Arabidopsis bZIP1 Transcription Factor Binding to the ABRE Cis-Element Regulates Abscisic Acid Signal Transduction

SUN Xiao-Li, LI Yong, CA Hua, BAI Xi, JI Wei, JI Zuo-Jun, ZHU Yan-Meng

Acta Agron Sin. 2011, 37(04):  612-619.  doi:10.3724/SP.J.1006.2011.00612

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Abscisic acid (ABA) is a phytohormone and mediates the response and adaptation of higher plants to various environmental stresses during vegetative growth. The basic leucine zipper (bZIP) transcription factors are also important regulators of plant development and abiotic resistance, acting through either ABA-dependent or ABA-independent mechanisms. In this study, we investigated and characterized the involvement of the AtbZIP1 gene in plant responsiveness to ABA. As confirmed by PCR and RT-PCR, AtbZIP1 has been silenced in mutant Arabidopsis ko-1 (SALK_059343) and ko-2 (SALK_069489C). The AtbZIP1 knockout plants demonstrated reduced sensitivity to ABA both at the seed germination stage and the seedling stage, with improvements in rates of germination, leaf opening/greening and primary root length. In order to investigate whether the regulation of AtbZIP1-mediated ABA responsiveness depended on the ABA-responsive elements (ABRE), we expressed the AtbZIP1 HIS6 fusion protein in E. coli andfound that the AtbZIP1 HIS6 specifically bound to the ABRE cis-elements. Semi-quantitive RT PCR showed that AtbZIP1 disruption altered expressions of some ABA responsive genes such as NCED3, RD22, KIN1, and RD29A. Our results indicated that AtbZIP1 regulates abscisic acid signal transduction by binding to the ABREs and altered the expressions of the ABA responsive genes.

Expression Characteristic on TaPDC-E1a Gene and Its regulatory Enzymes Gene in Male Sterile Line of Wheat (Triticum aestivum)

ZHANG Long-Yu, YUAN Lei, YANG Shu-Ling, ZHANG Gai-Sheng-*, WANG Jun-Sheng, SONG Yu-Long, ZHAO Zhuo-Jun, NIU Na, MA Shou-Cai

Acta Agron Sin. 2011, 37(04):  620-628.  doi:10.3724/SP.J.1006.2011.00620

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To deeply study the mechanism of male sterility induced by gametocide SQ-1 in wheat (Triticum aestivum L.), we isolated TaPDC-E1a gene using silcon cloning technique. The open reading frame of this gene is 1 401 bp in length, putatively encoding 388 amino acids. This gene possesses the conserved TPP domains. Two potential phosphorylation sites of serine residues might be present in the TaPDC-E1a protein of wheat. According to semi-quantitative RT-PCR analysis, the expression levels of TaPDC-E1a in the physiological and genetic male sterile lines were lower than those in fertile lines. Compared with fertile lines, the expression of PDK was obviously down-regulated in the physiological male sterile line induced by SQ-1. However, PDK gene was highly expressed in the genetic male sterile lines. The expression levels of PDP gene were similar in fertile and male-sterile lines. These results suggest that the pathway of energy metabolism of sterile line induced by SQ-1 is more susceptible than that of genetic male-sterile line.The upstream signal mechanism of mediating PDK gene may be inconsistent between male-sterile line induced bySQ-1 and genetic male-sterile line.

Gene Mapping of a Novel Mutant ahl in Rice

WANG Zeng, LI Yun-Feng, MA Jiao, REN De-Yong, WANG De-Zhong, YU Xiao-Qiang, SANG Xian-Chun, HE Guang-Hua

Acta Agron Sin. 2011, 37(04):  629-634.  doi:10.3724/SP.J.1006.2011.00629

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Theresearch on rice flower development gene is very important in molecular breeding of rice for related traits. A rice flower mutant abnormal hull and lodicule (ahl) was identified from Jinhui 10 (Oryza sativa L. ssp. indica) treated by EMS. In ahl mutant, lemma and palea minished and significantly twisted along with the apparently elongated apical lodicules. This minished lemma and palea led toabnormal kernelsafter grain filling, meanwhile, the 1000-grain weight decreased. The trait wassteadily inherited, and controlled by a pair of recessive gene.Using bulked segregation analysis method AHL was restricted between SSR markers RM14153 and RM14167, with genetic distances of 1.34 cM and 1.19 cM respectively, which covered an approximate 226 kb region on the chromosome 2. The result is useful for further map-based cloning and functional analysis of AHL gene.

Genetic Diversity and Relationship of Flax Germplasm as Revealed by AFLP Analysis

LI Ming

Acta Agron Sin. 2011, 37(04):  635-640.  doi:10.3724/SP.J.1006.2011.00635

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Flax (linum usitatissimum) is one of the major fibre and oil yielding crops. AFLP is very useful molecular marker for a number of plant species. To reveal the genetic diversity and find ways to broaden the genetic background of Chinese fibre flax varieties, we analyzed 18 Chinese fibre flax cultivars and other 67 accessions (including linseed, landrace and wild species) from different countries in the world by using AFLP marker. In total, 168 polymorphic alleles were detected with seven pairs of AFLP primer. For each pair of primer, 24 alleles on the average was detected in all accessions. Unweighted pair-group method with arithmetical averages (UPGMA) cluster analysis was used to estimate the genetic distances and to construct a dendrogram by NTSYS 2.1. The results showed that all 85 accessions were classified into four groups at 0.53 of similarity coefficient, which distinguish the varieties of flax (Linum usitatissimum) from three wild flax species. All varieties of flax were classified into five sub-groups (all fibre flax accessions were in one sub-group and the most of linseed accessions divided into other four sub-groups) at 0.67, indicating linseed possessed genetic basis broader than the fibre flax. In Chinese fibre flax varieties, Heiya cultivars had high genetic similarity, and its genetic basis was narrower than that of Shuangya variety. The results also showed that there were close relationship between Linum bienne and Linum usitatissinum, and sustained the hypothesis that fibre flax has evolved from linseed.

Molecular Cloning and Tissues Expression Analysis of Three Actin Genes from Mulberry (Morus alba)

LI Jun, ZHAO Ai-Chun, WANG Qian-Ling, ZHANG Qiong-Yu, LI Ji-You, JIN Xiao-Yun, LI Tian-Gang, TU Mao-De

Acta Agron Sin. 2011, 37(04):  641-649.  doi:10.3724/SP.J.1006.2011.00641

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Actins play many extremely important roles in plant, but none full-length cDNA actin genes were reported in mulberry until now. Three core fragments, two full CDS and one full-length genomic sequence of actin genes from mulberry were obtained with the strategies of homologous cloning and PCR in this research. Three mulberry actin genes obtained were designated as MaACT1, MaACT2, and MaACT3, respectively. The full-length of MaACT2 was 1 704 bp, which consisted of four exons and three introns, and 377 amino acidswere encoded by 1 134 bp of a putative CDS of MaACT2. The expression profile of three actins in leaf, stem, fruit and root was analyzed by RT-PCR. The results showed that MaACT1 was expressed low in stem, highen with the development of stem and high in young leaf. While MaACT2 and MaACT3 were expressed highly and stably in root, leaf and stem. The results showed MaACT3 was a good candidate for a control gene in the mulberry expression study because it can be expressed highly and stably in different tissues during their development.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Effects of Leaf Number of Stock or Scion in Graft Union on Scion Growth and Development of Soybean

GU Zhen, TUN Cun-Xiang, WANG Miao, SUN Hong-Bei, HOU Wen-Qing, JIANG Bing-Jun, HAN Tian-Fu

Acta Agron Sin. 2011, 37(04):  650-660.  doi:10.3724/SP.J.1006.2011.00650

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To elucidate whether there exist floral stimuli and inhibitors in flowering process, what the underlying mechanism is, and how they regulate plant growth and development, we used the early-maturing soybean cultivar Heihe 27 and late-maturing cultivar Zigongdongdou as stock and scion, respectively to make graf in which scions and stocks had different leaf numbers in combination with defoliation, and to study the effect of leaf number of stock and scion on the reproductive development. Under long-day (16 h) conditions, Zigongdongdou scions flowered at day 30 after being grafted onto Heihe 27 stocks, while its self-grafts failed to flower until the experiment finished (over 120 days). It suggested that under noninductive photoperiods (long-day), the transmissible floral stimuli were produced in the leaves of the early-maturing Heihe 27 and moved to the apical meristem of the late-maturing Zigongdongdou to induce the scion to flower. And the effect of the stock on the flowering of the scion was dependent on the number of leaves remained in the stock. It indicated that there exists an accumulative effect of the transmissible stimuli on soybean flowering. Defoliation on scions promoted flowering and increased flower number, which showed that some floral inhibitors were produced in the leaves of scions under long-day conditions. The number of flowers and pods on scions negatively correlated with the number of remained scion leaves. It indicated that the floral inhibitors suppress the development of the reproductive organs, and the inhibitions have an accumulative effect as well. The node location where scions were defoliated also had an effect on the flowering development. It was proposed that, during the growth and development of soybean, leaves regulate the amount and balance of floral stimuli and inhibitors based on photoperiodic signals, consequently trigger the proceeding from vegetative growth to the reproductive development to ensure the completion of life cycle.

Effects of Potassium and Calcium on Root Exudates and Grain Quality during Grain Filling

LIU Li-Jun, CHANG Er-Hua, FAN Miao-Miao, WANG Zhi-Qin, YANG Jian-Chang

Acta Agron Sin. 2011, 37(04):  661-669.  doi:10.3724/SP.J.1006.2011.00661

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Potassium (K) and Calcium (Ca) play important roles in regulating plant growth and development. The purpose of this study was to investigate how K and Ca nutrients affect the changes in the root exudates and their relations with appearance quality, eating and cooking quality using two rice cultivars, Yangdao 6 (indica) and Yangjing 9538 (japonica). Five treatments, 0K (without K), 1/2K (1/2 K of the standard Espino nutrition solution), 0Ca (without Ca), 1/2Ca (1/2 Ca of the standard Espino nutrition solution), and CK (standard Espino nutrition solution) were conducted from the heading stage to maturity. The results showed that 0K significantly decreased root activity, ATPase activity and the concentrations of citric acid, and Ca²⁺, K⁺, and NH₄⁺ in the root exudates, accelerated root senescence. The treatment of 0Ca significantly decreased the concentrations of oxalic acid, Ca²⁺, K⁺ and NH₄⁺ in the root exudates. The concentration of oxalic acid was very significantly and positively correlated with chalky kernel percentage, chalkiness and gel consistency in rice. And the concentration of citric acid was very significantly and negatively correlated with chalky kernel percentage, chalkiness and the value of breakdown, whereas very significantly and positively correlated with the value of setback. The concentrations of K⁺ and Ca²⁺ in root exudates during early or middle grain filling period (10 d or 20 d after heading stage) were significantly or very significantly and negatively correlated with chalky kernel percentage, chalkiness and amylose content. The concentration of NH₄⁺ in the root exudates was also very significantly and negatively correlated with amylose content in rice grains. These results indicate that root exudates are closely associated with grain quality, and K and Ca could regulate root exudates, and consequently, affect grain quality in rice.

Effect of Plant Growth Regulators on the Growth of Rice Tiller Bud and the Changes of Endogenous Hormones

LIU Yang, DING Yan-Feng, WANG Jiang-Cheng, LI Gang-Hua, HU Dun-Xu, LIU Zheng-Hui, WANG Chao-Hua-*

Acta Agron Sin. 2011, 37(04):  670-676.  doi:10.3724/SP.J.1006.2011.00670

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Hormones have substantial effect on tiller bud growth of rice. However, little is known on the relation between endogenous hormonal changes and the growth of rice tiller bud induced by exogenous hormones. In present study, two rice cultivars (Yangdao 6 and Nanjing 44) were used to investigate the effect of exogenous ABA, GA₃ and NAA on tiller bud outgrowth and the changes of endogenous hormones. The results showed that exogenous GA₃ and NAA completely inhibited the tiller bud growth, while applied ABA did not, but ABA slowed the growth rate of it. Both exogenous GA₃ and NAA increased the ABA contents and decreased the Z+ZR contents in tiller node and tiller bud, and exogenous GA₃ increased the IAA content in tiller node, and IAA and Z+ZR changed earlier than ABA. In conclusion, IAA and Z+ZR may play key roles in regulating the growth of rice tiller bud, while ABA may not, although ABA can affect the growth velocity of tiller bud; the effect of exogenous hormones on rice tiller bud growth is through regulating the contents of ABA, IAA and CTK in plants.

Population Production Capacity of Direct-Seeding Rice in Central Jiangsu Region and Effects of Nitrogen Application

ZHANG Jie-Jian, XIE Cheng-Lin, XIE Ren-Kang, LANG Wei-Zhong, YANG Lan, ZHANG Ju-Fang, SHU Qiang-Sen

Acta Agron Sin. 2011, 37(04):  677-685.  doi:10.3724/SP.J.1006.2011.00677

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In recent years, cultivation area of direct-seeding rice in Jiangsu and nearby regions has been expanding rapidly, but the specific research on cultivation and breeding is very little. In this study, based on investigation of the productivity levels of direct-seeding rice in central Jiangsu province, we carried out a test of nitrogen application amount and nitrogen application ratios for direct-seeding rice, to explore the response of dry matter growth and yield to nitrogen fertilizer application. The result showed that, the average yield of direct-seeding rice in central Jiangsu province was 7 710 kg ha^-1, which was significantly lower than that of mechanical and manual transplanted rice; the nitrogen fertilizer rate was generally more than 270 kg N ha^-1, and the unreasonable application of nitrogen was widespread. Plot experiments showed that the application rate of nitrogen affected yield through panicles per unit area and spikelets per panicle, while the application ratio of nitrogen mainly had influence on spikelets per panicle. In the experimental condition, the highest yield was gained when the nitrogen rate was 270 kg N ha^-1 and the ratio of basal : tillering : panicle was 4:3:3. When the fertilization is in the optimum conditions, the direct-seeding rice will have more reasonable population structure, higher dry matter production capacity both for individuals and population, more suitable harvest index (0.53 or so) and higher resistance to lodging. The pathway to increase yield and the characteristics for high-yielding direct seeding rice population were also discussed.

Effects of Lucerne Removal Time on Soil Water and Productivity in a Lucerne- Wheat Rotation on the Western Loess Plateau

LI Ling-Ling, HUANG Gao-Bao, ZHANG Ren-De, CA Li-Qun, LUO Zhu-Zhu, JIN Xiao-Jun, ZHANG En-He, BELLOTTI Bill, UNKOVICH Murray

Acta Agron Sin. 2011, 37(04):  686-693.  doi:10.3724/SP.J.1006.2011.00686

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Rainfed spring wheat (Triticum aestivum L.) is the most important cereal crop on the Western Loess Plateau. Lucerne (Medicago sativa L.) has been very popular. There are problems associated with both continuous cropping and with perennial lucerne systems. The key challenge for rain-fed cropping systems is to adopt strategies that make optimal use of water. Developing lucerne-wheat rotation systems will have significant benefits for agriculture development on the Loess Plateau，nevertheless, it is very important to terminate lucerne at the right time as it affects soil moisture. However, very little research has been done on the timing for termination of old lucerne in the semiarid areas of the Western Loess Plateau. Based on field experiments conducted in a typical semiarid area on the Western Loess Plateau, this paper aimed to investigate the soil water and termination timing of 30a old lucerne on the productivity of lucerne-wheat rotation. The results showed that the soil profile after long-term lucerne was very dry down to 3 meters, the three year experiment period was not sufficient to allow soil water recharge, even after a high rainfall year. Time of 30a old lucerne removal (in spring or later in the year) had no significant effect on soil water regimes. As a result, weeds became more competitive, the old lucerne stand showed poor dry matter, yield, had no response to 1kg ha^-1 of N application, and was overdue for termination. Following spring wheat made no response to 1kg ha^-1 of N fertilizer due to dry soil profile after 30 years lucerne growing.

Growth and Yield Formation of No-Tillage Direct-Seeding Rapeseed in Hubei Double Cropping Rice Area

WANG Cui-Cui, CHEN Ai-Wu, WANG Ji-Jun, ZHANG Dong-Xiao, SHANG Song, ZHOU Guang-Sheng, HU Li-Yong, WU Jiang-Sheng, FU Ting-Dong

Acta Agron Sin. 2011, 37(04):  694-702.  doi:10.3724/SP.J.1006.2011.00694

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After harvest of late rice, most farmlands in the Yangtze River basin are often fallow through winter due to tight rotation and heavy clay soil. For evaluating the possibility in application of the no-tillage and direct-seeding model for rapeseed production in the double cropping rice area, the split-plot experiments were carried out in the three locations in double cropping rice area of Hubei. Several parameters related to growth in terms of plant individual and population, grain yield and its components were measured under the three nitrogen levels and at four planting densities. The results showed that: (1) the no-tillage and direct-seeding decreased  growth duration, especially the seedling stage, and biomass accumulation from emergence to the early budding stage, while increased growth at the late budding stage in spring; (2) nitrogen rate and planting density had significant effects on growth and yield of rapeseed by improving the individual and population qualities; (3) the yields of rapeseed achieved 2 250 kg ha^–1 at the planting densities of 45×10⁴–60×10⁴ plants hm^–2 under the nitrogen level of 270 kg ha^–1, which exceeded the average yield in Hubei. The results suggested the no-tillage and direct seeding model for rape planting could be applied in double cropping rice area of Hubei, and the optimization in nitrogen rate and planting density could result in high yield of rapeseed.

Changes of Photosynthetic Characteristics in Top Three Leaves of Rice (Oryza sativa L.) Cultivars in Released Different Years in Jilin Province

JIANG Nan, DI Yu-Ting, XU Ke-Zhang, ZHAO Guo-Chen, LING Feng-Lou, WU Zhi-Hai, ZHANG Chi-An

Acta Agron Sin. 2011, 37(04):  703-710.  doi:10.3724/SP.J.1006.2011.00703

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In order to understand the changes of photosynthetic characteristics in top three leaves and its relationship with yield in the genetic improvement of rice, 33 typical japonica rice cultivars released from 1958 to 2005 were planted under field conditions. to determine net photosynthetic rate (P_n), photosynthetic capacity and leaf sources capacity (LSC) after heading stage. The result indicated that the P_n, photosynthetic capacity and LSC of flag-leaf at heading had the most contribution to plant photosynthetic capacity, which was account to 42.45%, followed by those of top 2nd leaf with 28.27% and those of top 3rd leaf with 15.69%. While, within 47 years genetic improvement of rice cultivars, the increase of P_n, photosynthetic capacity and LSC of the top 3rd leaf were the maximum, and those of flag-leaf was the minimum.The correlations of P_n, photosynthetic capacity and LSC of flag-leaf and top 2nd leaf with yield were not obvious enough to reach significant level after heading. The P_n of top 3rd leaf and the photosynthetic capacity of plant were significant positive correlation with yield at heading and 10 days after heading. The photosynthetic capacity and LSC of top 3rd leaf were highly significant positive correlation with yield after heading, and those of flag-leaf and top 2nd leaf were not. Our studies indicate that the significant increase of P_n, photosynthetic capacity and LSC in the top 3rd leaf is mainly resulted from the yield genetic improvement of rice cultivars for 47 years in Jilin province, but there has been no obvious change in photosynthetic capacity of flag-leaf.

Physiological Basis of Improving Soluble Sugar Content in Sweetpotato for Table Use by Humic Acid Application

LIU Hong-Juan, LI Zuo-Mei, SHI Chun-Yu, ZHANG Li-Ming

Acta Agron Sin. 2011, 37(04):  711-716.  doi:10.3724/SP.J.1006.2011.00711

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Soluble sugar content is a main index of edible quality in storage root of sweetpotato for table use.  Previous research showed that soluble sugar content in storage organs of plants was increased significantly by application of humic acid (HA), butthere have been little research on their physiological basis. The objective of this study was to clarify the physiological basis of soluble sugar content improvement in storage root of sweetpotato by using humic acid. The typical varieties of sweetpotato for table use (Beijing 553) was grown in a replicated experiment at agricultural experiment station of Shandong Agricultural University in two summer growing seasons of 2008 and 2009. The treatments included the control and treatment applied HA. The changes of starch content, soluble sugar content and relative enzymes activity during root tuber development, and sucrose content and relative enzymes activity in functional leaves were determined by using periodic sampling during storage root development. The results showed that compared with the control, sucrose phosphate synthase (SPS) activity and sucrose content in functional leaves were increased significantly, with the average increase of 30.90% and 9.48% during whole growth period, while sucrose synthase (SS) activity in storage root was decreased significantly with the average declines by 11.04%, that could promote accumulation of sucrose and fructan in storage root in treatment of HA. Amylase activity in treatment of applying HA was increased significantly with the average increase of 11.33% and 15.70%, respectively for α-amylase and β-amylase activity, that enlarged the accumulation of fructose and glucose in storage root. At harvest, the soluble sugar content was increased by 15.49% and the starch content was decreased by 3.56%. The increase of sucrose content, the decrease of the inversion quantity from soluble sugar to starch and the hydrolysis enhancement of starch in storage root are the physiological basis of increasing soluble sugar of storage root.

RESEARCH NOTES

Genetic Analysis and Mapping of glup-t Gene for 57H Mutant in Rice

TIAN Meng-Xiang, CHEN Chao, ZHANG Ya-Dong, ZHU Zhen, ZHAO Qiang-Yong, ZHOU Li-Hui, YAO Shu, WANG Yan-Peng, WANG Cai-Lin

Acta Agron Sin. 2011, 37(04):  717-722.  doi:10.3724/SP.J.1006.2011.00717

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Glutelins are major storage protein and account for 80% of the total protein found in starchy endosperm in rice. They are synthesized on rough endoplasmic reticulum as 57 kD precursors, and then processed into acidic and basic subunits in PB-II. Mutation of the gene controlling the synthesis of glutelin will result in an formation with high amount of 57 kD glutelin precursor, named 57H mutant. In this study, we reported a novel rice 57H spontaneous mutant, Xilaoshuya, which showed increased amount of 57 kD and 13 kD polypeptides, the decreased amounts of 37–39 kD and 22–23 kD polypeptides. Four F₂ segregation populations derived from crosses between Xilaoshuya and Wuyunjing 7, 02428 were used to study the inheritance and gene mapping for 57H mutant. The results suggested that, the mutant trait in Xilaoshuya was controlled by a pair of recessive nuclear gene and designated tentatively as glup-t. By means of molecular marker technique, the glup-t gene was mapped between CAPS4-3 and Indel4-7, Indel4-8 on the long arm of chromosome 4, and all of the genetic distances to the three markers were 0.26 cM.

Cloning and Analysis of β-Glucan Synthase Gene AsCSLH in Avena sativa L.

WU Bin, ZHANG Zong-Wen

Acta Agron Sin. 2011, 37(04):  723-728.  doi:10.3724/SP.J.1006.2011.00723

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Beta-glucan [(1→3, 1→4)-β-D-glucan] is one of the important components in oat (Avena sativa L.) that has the function of health protection for human beings. Cloning the β-glucan synthase gene is of significance to reveal the molecular mechanism of β-glucan accumulation and guide oat breeding for β-glucan enhancement. A β-glucan synthase gene, designated AsCSLH, and its genomic DNA sequence were cloned from the oat landrace Xiayoumai using rapid amplification of cDNA ends (RACE) and GenomeWalk from the cDNA, respectively. The AsCSLH gene contains a 2 277 bp open reading frame and encodes a peptide of 758 amino acid residues. Six introns were found in AsCSLH gene with typical GT/AG characteristic after comparison of its sequences of genomic DNA and cDNA. Sequences analysis showed that AsCSLH gene shared the highest identity with rice CSLH gene (BK000084). Structure analysis of predicted encoded protein also confirmed that this cDNA sequence was the oat β-glucan synthase gene. The tissue-specific expression analysis by semiquantitative RT-PCR assays suggested that AsCSLH was expressed in different tissues of oat with the highest level in immature seeds. These results suggested that AsCSLH plays an important role in oat β-glucan synthesis.

Status of Nutrient Use Efficiencies of Rapeseed in the Yangtze River Basin

ZOU Juan, LU Jian-Wei, CHEN Fang, LI Yin-Shui

Acta Agron Sin. 2011, 37(04):  729-734.  doi:10.3724/SP.J.1006.2011.00723

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Nutrient use efficiency is an important index not only for fertilizer recommendation on the field scale but also for forecasting fertilizer demand on the regional and national scales, however, exact nutrient use efficiencies of rapeseed in the Yangtze River Basin have not been well known yet. In this paper, data from 74 field experiments were collected and used for analysis and evaluation of partial factor productivity (PFP), agronomic efficiency (AE), apparent recovery efficiency (RE), physiological efficiency (PE), and fertilizer contribution index of rapseed. The results indicated that AE averaged 6.2 kg kg^–1 N, 6.3 kg kg^–1 P₂O₅, and 2.6 kg kg^–1 K₂O, respectively. RE averaged N 34.0%, P₂O₅ 17.4%, and K₂O 36.9%, respectively. The averages of PE were 18.5 kg kg^–1 N, 35.5 kg kg^–1 P₂O₅, and 9.1 kg kg^–1 K₂O. The contribution of N, P and K fertilizer to rapeseed yield was 41.9%, 21.4%, and 11.5%, respectively. It was concluded that nutrient use efficiencies of rapeseed in the Yangtze River Basin were low. Thus, rapeseed yield and nutrient use efficiencies should be improved simultaneously to ensure sustainability for rapeseed production.

Root Characteristics of Super High-Yield Spring Maize

ZHANG Yu-Qin, YANG Heng-Shan, GAO Ju-Lin, ZHANG Rui-Fu, WANG Zhi-Gang, XU Shou-Jun, FAN Xiu-Yan, BI Wen-Bo

Acta Agron Sin. 2011, 37(04):  735-743.  doi:10.3724/SP.J.1006.2011.00735

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Using cultivar Jinshan 27 as test material and high-yield maize cultivar as the control, we analyzed the root characteristics of super high-yield maize. The results showed that the percentage of roots in deep soil was higher, the biggest roots width tended to be deeper, the number of root per plant in deep soil layer increased for super high-yield maize, and the difference of root parameters enlarged with the increase of the soil depth compared with the control. The root dry weight was first up then down in the growing process, and the maximum value appeared at silking stage and showed extremely difference from the control. The percentage of root weight at 0–20 cm soil layer was lower obviously than the control, and that at the soil layer over 40 cm was more than the control at every growing stage. Ratio of shoot/root was close to the control at early growth stage, and lower than the contrastat later growing stage. Changes of rootvigor showed a single apex curveingrowing and the peak value appeared at silking stage. Root vigor at every growing stage changed as a single apex curve with the increase of soil depth under super high-yield cultivation, but root vigor of the control changed greatly in different growing stages. The activities of SOD&POD of root system per soil layer were higher than the control at silking and milking stages in super high-yield maize, but MDA content was lower than the contrast. The root growing condition and nutrient supply were improved by deep ploughing, optimizing fertilization and high planting density, which not only improve the deep root growing, but also keep root a higher physiological activity, providing a basis for production of super high-yield maize.