Table of Content

12 May 2009, Volume 35 Issue 5

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Identification and SSR Mapping of Two Powdery Mildew Resistance Genes in Wild Emmer (Triticum dicoccoides) Accessions IW3 and IW10

LI Gen-Qiao,FANG Ti-Lin**,ZHANG Hong-Tao,XIE Chao-Jie,YANG Zuo-Min,SUN Qi-Xin,LIu Zhi-Yong

Acta Agron Sin. 2009, 35(5):  761-767.  doi:10.3724/SP.J.1006.2009.00761

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Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a major wheat disease in the world. Deployment of resistant varieties is considered the most economical and effective way for controlling the disease. Wild emmer is one of the important genetic resources for wheat disease resistance genes. Two wild emmer accessions, IW3 and IW10, collected from Mount Hermon, Israel, are highly resistant to prevailing Bgt isolate E09. Genetic analyses of the F₂ populations and F₃ progenies derived from the crosses between Triticum durum cultivar Langdon and IW3 or IW10 indicated that each accession possessed a single dominant gene, temporarily designated MlIW3 and MlIW10, respectively, conferred resistance to Bgt isolate E09. Bulked segregant analysis (BSA) and SSR mapping revealed that both MlIW3 and MlIW10 were flanked by SSR markers Xbarc84 and Xwmc326 with genetic distances of Xbarc84–4.6 cM–MlIW3–1.6 cM–Xwmc326 and Xbarc84–6.6 cM–MlIW10–0.6 cM–Xwmc326. Both MlIW3 and MlIW10 were physically mapped on the distal bin of chromosome 3BL using Chinese Spring nullisomic–tetrasomic, ditelisomic, and deletion lines. According to the collecting geographic sites of IW3 and IW10 in Israel and the SSR mapping data, MlIW3 and MlIW10 appear to be the same or allelic to wild emmer derived powdery mildew resistance gene Pm41 or in the same cluster with it.

Gene Expression Profile and Main Function Genes during Ear Development in a Highly Heterotic Hybrid of Maize

LI Bo,ZHANG Deng-Feng,JIA Guan-Qing,ZHANG Ti-Fu,DAI Jing-Rri,WANG Shou-Cai*

Acta Agron Sin. 2009, 35(5):  768-777.  doi:10.3724/SP.J.1006.2009.00768

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The development of ears is mostly responsible for the yield of maize (Zea mays L.), however, the molecular basis is unclear. To disclose the differential expression genes involved in the development of maize ear and their expression patterns, the gene expression at genome level of a highly heterotic hybrid (C8605-2×W1445) was detected from ear spikelet differentiation initiation to the later 8 d using microarrays with approximately 58 000 probes. The result of microarray analysis was verified using quantitative real-time PCR. A total of 671 genes expressed differentially which consisted of four expression patterns. These genes were involved in several biological processes, such as metabolism, development, responses to stimulus, cell signal transduction, and transport. Most genes for cell division, cell wall structure, and the modified protein of cell wall structure were identified to be upregulated during the ear development. Thus, these genes may play important roles in cell differentiation and formation of agronomic traits in maize ears. Moreover, genes for protein kinase, signal transduction, and transcription factors, which are involved in signal transduction and regulatory processes, may also take great functions in the development of maize ears.

Genetic Contribution of Introduced Varieties to Wheat Breeding in China Using SSR Markers

LI Xiao-Jun,XU Xin,LIU Wei-Hua,Li Xiu-Quan,YANG Xin-Ming,LI Li-Hui*

Acta Agron Sin. 2009, 35(5):  778-785.  doi:10.3724/SP.J.1006.2009.00778

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Foreign germplasm has exerted important influence on wheat (Triticum aestivum L.) breeding in China. To uncover the genetic contribution of introduced varieties to Chinese wheat breeding, 44 representative accessions, consisting of 11 introduced important parents from 1950s to 1970s and 33 representative domestic varieties which were released in different years in China, were evaluated using 363 SSR markers distributing on 21 chromosomes. The 11 introduced accessions contained 76.3% of the alleles presented in total 33 Chinese accessions. Comparing the pattern of variability among introduced accessions and the groups of varieties released over time, we found that the mean number of alleles amplified was the highest in foreign germplasm (3.92), similar to each other between 1960s and 1970s (2.86 and 3.01, respectively), and that in 1980s was a little higher (3.46). The result on genetic distance among different groups was accorded with the pattern of the allelic diversity. On the other hand, comparing the allelic frequencies between introduced and improved accessions at each SSR locus we found that certain chromosomal regions underwent strong selection in wheat breeding. At least 33 SSR loci on 14 chromosomes with the exception of 4A, 6A, 7A, 1B, 3B, 3D, and 5D, the alleles amplified in foreign accessions were selected preferentially and transmitted to Chinese accessions, whose frequencies were over 70% in either group of accessions. Furthermore, some of the markers were correlated with known wheat genes controlling important traits reported in literatures, including resistance to pests such as strip rust, leaf rust and powdery mildew, and other characters such as yield, growth stage and dormancy. In conclusion, the chromosomal regions selected preferentially play an important role in the improvement of wheat in China, which should be studied further.

Cloning and Characterization of a Novel Wheat Glycoside Hydrolase Gene TaGlc2 Induced by Powdery Mildew Pathogen(Erysiphe graminis) Infection

Ramesh N PUDAKE,XIN Ming-Ming,YIN Yu-Jing,XIE Chao-Jie,NI Zhong-Fu,SUN Qi-Xin

Acta Agron Sin. 2009, 35(5):  786-794.  doi:10.3724/SP.J.1006.2009.00786

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Fungal diseases cause serious yield losses of wheat worldwide. Up to date, numerous genes involved in the wheat-pathogen response have been identified. These include pathogenesis related (PR) genes and antifungal hydrolases such as glucanase and chitinase genes. Recently, there has been increasing number of studies providing evidence of the potential involvement of 1,3-β-glucanase in defense against fungal infection. In this study we identified a cDNA encoding a 1,3-β-glucanase, designated TaGlc2, from wheat cDNA library. The deduced peptide sequence of TaGlc2 is similar to a glycoside hydrolase family 17. Using real time PCR, the expression pattern of TaGlc2 in wheat seedlings inoculated with powdery mildew pathogen (Erysiphe graminis) was determined. The results showed that TaGlc2 is inducible in response to fungal infection. The 5' genomic region of TaGlc2 was isolated and it contains some cis-elements which are reported to be involved in pathogenesis response.

Evaluation for Tolerance Characteristics of Different Rice Varieties to Brown Planthopper(BPH),Nilaparvata lugens Stal

CHEN Jian-Ming,YU Xiao-Ping,CHENG Jia-An

Acta Agron Sin. 2009, 35(5):  795-801.  doi:10.3724/SP.J.1006.2009.00795

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Brown planthopper (BPH), Nilaparvata lugens Stål, is one of the most serious insect pests of rice in China and other southeast Asia countries. In the paper, tolerance characteristics of 10 different rice varieties was analyzed using tolerance index, antibiosis index, functional plant loss index (FPLI) and population number of BPH F₁ generation at rice seedling and adult stages. The results showed that when plants were infested by eight 1–2 instars and 3–4 instars BPH nymphs at seedling stage, respectively, the plants of different varieties expressed some difference in tolerance levels. Tolerance indexes of these varieties including Shanyou 63, Xiushui 11, Pei’ai 64S/E32, Triveni, Utri Rajapan, ASD7, and Jiayu 948 were greater than their antibiosis indexes, Especially for Shanyou 63. While tolerance index of IR64, Rathu Heenati was obviously less than antibiosis index. When rice plants were infected with 3–4 instar nymphs, its tolerance index increased. For the same variety, tolerance index at adult stage was obviously higher than that at seedling stage. Under the infection by same number of BPH, the plants of varieties Xiushui 11 and TN1 died (9 level), Pei’ai 64S/E32, Shanyou 63, Jiayu 948, Triveni and Utri Rajapan plants expressed middle damage level (3–5 level), ASD7 and IR64 less damage level (<3 level), Rathu Heenati no damage. Population number of BPH on Xiushui 11, Shanyou 63 and Pei’ai 64S/E32 had no obvious difference from that on TN1, and was significantly higher than that on other varieties, with that on Jiayu 948, Triveni, Utri Rajapan > that on ASD7 > that on Rathu Heenati. These results above mentioned indicated that TN1, Shanyou 63 and Xiushui 11 are susceptible, has no tolerance and antibiosis characteristics; Pei’ai 64S/E32, Triveni, Utri Rajapan belongs to the group of stronger tolerance; IR64, Rathu Heenati are of high antibiosis; ASD7 and Jiayu 948 belongs to the group of both tolerance and antibiosis. Therefore, it is concluded that tolerance characteristics of different rice varieties will be determined by the method using in the paper. This will provide a useful screening method in tolerant varieties breeding and be of important significance to sustainable management of BPH.

Localization of MLPK and SSP Genes for Self-Incompatibility of Brassica oleracea by Fluorescence in situ Hybridization

RONG Xiao-Ying,ZHU Li-Quan,WANG Yong,GAO Qi-Guo,CHEN Xiao-Dan,YANG Yang

Acta Agron Sin. 2009, 35(5):  802-808.  doi:10.3724/SP.J.1006.2009.00802

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In Brassica, self-incompatibility recognition is controlled by the multiallelic gene complex (S-haplotypes) at the S-locus, which encodes both the male determinant S-locus pollen coat protein (SCR/SP11) and the female determinant S-locus receptor kinase (SRK). Studies of MLPK and SSP genes for self-incompatibility of Brassica have been gradually widespread since they were identified. However, the position and copy number of MLPK and SSP genes in Brassica oleracea genome are still unclear. In this paper, the localization of MLPK and SSP genes for self-incompatibility of Brassica oleracea on prometaphase chromosomes, early pachytene chromosomes and extended DNA fibers was conducted successfully by fluorescence in situ hybridization. The results indicated that MLPK probe was hybridized onto the short arm of a pair of homologous prometaphase chromosomes, and the percent distance from centromere to the signal point was about 53.41±3.16; SSP probe was hybridized onto the long arm of a pair of homologous prometaphase chromosomes with the satellite, and the percent distance from centromere to the signal point was about 78.36±4.26. Hybridization signals from three kinds of cytological targets with different FISH resolutions showed that both MLPK gene and SSP gene might be located at a single-copy locus in Brassica oleracea genome. Repeated FISH indicated that both MLPK and 5S rDNA probes were hybridized onto the same chromosomes. According to karyotype standard of Armstrong, it was primarily inferred that MLPK gene was located on the chromosome 2, and SSP gene on the chromosome 7. The results presumably revealed thatneither MLPK nor SSP is linked to S-locus. And they locate respectively on the different chromosomes in Brassica oleracea. In addition, the collinearity relationship of MLPK as well as SSP between Brassica and Arabidopsis thaliana was also discussed on the basis of comparative genomics.

Development of Transgenic High-Amylose Potato Using a Novelty RNAi Vector

GUO Zhi-Hong，WANG Ya-Jun，ZHANG Jin-Wen，ZHANG Yu-Bao，WANG Jin-Niu，XIE Zhong-Kui

Acta Agron Sin. 2009, 35(5):  809-815.  doi:10.3724/SP.J.1006.2009.00809

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Amylose from potato starch is of great advantage for applications in many fields because of its higher degree of polymerization and lower gelling temperature compared with cereal starch. But there is no natural mutant of high-amylose potato. RNAi technique is efficient and specific for plant gene silence but traditional RNAi vector is laborious to prepare. To design an easily-prepared RNAi vector and to develop transgenic high-amylose potato, PCR technique was employed to amplify the nos terminator, the tobacco axi1 and the tobacco ubi.u4 promoter, and to sub-clone a fused fragment SIII which is partially homologous to potato Sbe1 and to Sbe2. Then, a newly designed vector pCUSNI containing “ubi.u4 promotor–antisense SIII–antisense nos terminator–axi1 gene intron–sense nos terminator” was generated and transformed into potato varieties Longshu 3, Gannongshu 2, and Atlantic by Agrobacterium-mediated transformation. Sixteen transgenic potato plants were obtained, and the amylose content in 14 of them increased significantly, which ranged from 53.80% to 85.33% of total starch. But with the increase of amylose content, starch content decreased in transgenic potato plants. Results of semi-quantitative RT-PCR indicated that the accumulation of mRNAs for Sbe1 and Sbe2 was not detectable in transgenic plants with amylose content higher than 80%, indicating that the novel RNAi vector pCUSNI is highly efficient for the simultaneous silence of Sbe1 and Sbe2 in potato. The generation of the RNAi vector pCUSNI makes it much easier to prepare RNAi vectors targeting to other plant genes. The only thing is to insert a fragment of the target gene or the target genes in restriction sites between BamH I and Xba I in vector pCUSNI to replace SIII and there is no need to construct an inverted repeat of target gene.

Transferability of SSR from Adzuki Bean to Mungbean

WANG Li-Xie,CHENG Xu-Zhen,WANG Su-Hua,LIU Chang-You,LIANG Hui

Acta Agron Sin. 2009, 35(5):  816-820.  doi:10.3724/SP.J.1006.2009.00816

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SSR (Simple sequence repeat) has been a popular tool in genetic studies. However, only a few SSR markers are available in mungbean (Vigna radiata L.). Adzuki bean (Vigna angularis L.) is a close relative of mungbean. In the study reported in this paper, we tested the transferability of adzuki bean SSR markers into mungbean. A total of 187 sets of SSR primers were tested and about 75% of them generated repeatable and clear products in mungbean, indicating a high homology between these two genomes. Of the transferable SSRs, 28 sets of primers generated polymorphic products among 60 mungbean genotypes with a total of 81 alleles detected. The average PIC (polymorphic information content) value is 0.36. Based on the SSR fingerprints, the 60 accessions can be divided into different groups agreeing well with their geographical origins. The exotic accessions were well separated from the local genotypes, indicating the former could be important sources for broadening the mungbean gene pool. The present study identified useful SSR markers for mungbean research, which will undoubtedly accelerate the genetic study of this crop.

QTL Analysis of Yield，Yield Components and Lodging in Soybean

ZHOU Rong,CHEN Hai-Feng,WANG Xian-Zhi,ZHANG Xiao-JUan,SHAN Zhi-Hui,et al.

Acta Agron Sin. 2009, 35(5):  821-830.  doi:10.3724/SP.J.1006.2009.00821

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High-yield and stable-yield is the main goal of soybean breeding, but yield is a complex quantitative trait, which is very vulnerable to the environment. A total of 165 plants of recombinant inbred lines (RILs) derived from a cross between Zhongdou 29 and Zhongdou 32 were used to analyze the relationship of individual yield, yield components, lodging and the genetic effect, and to map the QTLs in two years. Thirty-eight QTLs for yield, seed and pod traits, and lodging related traits were detected by composite interval mapping (CIM) method, the majority of which were located on C2, F and I linkage groups. The QTL (qLD-15-1) for lodging on F linkage group was detected in both years, explaining over 20% of phenotypic variation, with the same or adjacent marker intervals to the QTLs for 100-seed weight and pods on branch, showing some correlation between yield related traits and lodging. On I linkage group, the QTLs for yield components of seeds per pod, two-seed-pods, three-seed-pods, and four-seed-pods were detected on the same position in two years, explaining 32–65% of phenotypic variation. The positive alleles of QTLs for seeds per pod, four-seed-pods, two-seed-pods and three-seed-pods were from different parents. The four QTLs for seed and pod traits mapped on the same position, which was consistent with the correlation analysis result of phenotypic traits, showing that the regulatory mechanisms of the four traits for seed and pod were different, which may provide an important basis for promotion of soybean yield by improving seed and pod traits.

QTL Mapping and QTL × Environment Interactions of Milling Quality and Percentage of Chalky Grain in Upland Rice Introgression Lines under Upland and Lowland Environments

LI Jun-Zhou,FU Chun-Yang,LI Zi-Chao

Acta Agron Sin. 2009, 35(5):  831-838.  doi:10.3724/SP.J.1006.2009.00831

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Milling quality and percentage of chalky grain of rice (Oryza sativa L.) are important traits to producers and consumers. The objectives of this study were to characterize the response of brown rice (BR), milled rice (MR), head milled rice (HMR), and percentage of chalky grain (PCG) to upland water stress and to identify QTLs for the traits. A set of 271 introgression lines (ILs) (BC₅F₃), carrying segments from upland cultivar IRAT109 in the background of lowland rice cultivar Yuefu, were used, and data were collected under upland and lowland environments. Great changes were detected between upland and lowland conditions in head milled rice and percentage of chalky grain, but relative stability in brown rice and milled rice. Head milled rice increased and percentage of chalky grain significantly decreased under upland condition. A total of ten additive QTLs and two pairs of digenic epistatic interactions QTLs for BR, MR, HMR, and PCG were detected on chromosomes 3, 4, 7, 8, and 9. The contribution of single QTL ranged from 1.81 to 17.49%, three QTLs (qMR9, qHMR7, qHMR9) and one pairs of digenic epistatic interactions (qHMR3~qHMR9) accounted for above 10% of the phenotypic variation. Six QTLs were no significant QTL × Environment interaction effects, seven QTLs were the same with those from previous reports, and two genomic intervals, RM1112~RM1272 on chromosome 4 and RM1189~RM410 on chromosome 9, were cluster regions of the QTLs. These co-localized QTLs and common QTLs will facilitate marker-assisted selection for grain quality traits in rice breeding.

Inheritance，Mapping and Qrigin of the Yellow-Seeded Traits in Brassica juncea

LIU Xian-Jun，YUAN Mou-Zhi，GUAN Chun-Yun，CHENille She-Yuan，LIU Shu-Yan，et al.

Acta Agron Sin. 2009, 35(5):  839-847.  doi:10.3724/SP.J.1006.2009.00839

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Seed coat color is not only a morphological indicator but also association with dormancy and quality of seed in Braasica. The seeds of Brassica species are divided into such categories as black, brown or yellow according to their coat color. The emphasis has been put on breeding for the yellow-seeded rapeseed in recent years. Most genetic studies showed that seed coat color is controlled by two duplicate loci in Brassica juncea. Chemical analysis and DMACA (p-dimethylaminocinnamaldehyde) staining confirmed that the yellow seed coat does not contain any proanthocyanidins while the black or brown seed coat does. Dihydroflavonol 4-reductase (DFR), anthocyanidin synthase (ANS), and anthocyanidin reductase (ANR) are the key enzymes of flavonoid biosynthetic pathway leading to production of proanthocyanidins. As revealed by RT-PCR, the genes encoding DFR, ANS and ANR are not expressed in the transparent testa of B. juncea yellow seeds. The two BC₆F₂ populations, derived from crossing and backcrossing the yellow-seeded parent Sichuan yellow to the black-seeded Purple-leaf mustard and comprised 143 or 141 individual plants, were used to map the loci controlling seed coat color in B. juncea by using SSRs and SCARs. The twenty-two B. juncea accessions collected from all over the world were genotyped for association analysis using the markers mapped. The expression of the genes encoding DFR, ANS, and ANR in seed coat at 20 days after pollination was investigated by RT-PCR in the twelve accessions. The allelism test was carried out by a diallel cross for the six yellow-seeded accessions from China, Canada, India or Russia. We mapped the two loci A and B controlling seed coat color on the linkage groups A9 and B3, receptively, and found the 22 linked markers flanking these loci. The closest markers flanking the locus A on A9 were the co-dominant markers SCM08 and Ni4-C09, which are 0.5 and 1.6 cM far from the locus, respectively. Although the marker CB10298 on one side of the locus B on B3 was also a co-dominant SSR marker with 0.8 cM from locus B, on the other side a RAPD marker S1096_-700 with 3.3 cM apart. The 0.9 and 1.5 cM-long chromosomal regions around these loci were revealed by association analysis to be conserved in all the yellow-seeded accessions genotyped. The expression of the genes DFR and ANS was not detected by RT-PCR in the yellow-seeded accessions investigated although these genes were found to be expressed in seed coat of all the black-seeded ones. The gene ANR was strongly expressed in all the black-seeded accessions studied, and not or weakly expressed in the yellow-seeded accessions. The F₁ plants of the fifteen combinations from diallel crossing of the six yellow-seeded accessions all produced yellow seeds, indicating the loci for seed coat color were allelic to each other in these parents. It is proposed from these results and previous studies that the gene controlling seed coat color is a transcription-factor-coding gene and all the yellow-seeded accessions derive from a single origin in Brassica juncea.

Allelic Composition and Expression of  Vernalization Gene Vrn-1 in Wheat Cultivar Zhengmai 9023

YUAN Xiu-Yun，LI Yong-Chun，MENG Fan-Rong，YAN Yan-Tao,YIN Jun

Acta Agron Sin. 2009, 35(5):  848-854.  doi:10.3724/SP.J.1006.2009.00848

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Zhengmai 9023 is an elite winter wheat (Triticum aestivum L.) cultivar grown in a large scale in China, and often injured by coldness when it easily starts reproductive growth before winter because of its weak vernalization characteristic. Vernalization gene VRN-1 is one of the key genes controlling the conversion from vegetative growth to reproductive growth in wheat. To explore the regulation mechanism of vernalization in Zhengmai 9023, the VRN-1 gene was cloned from leaf tissues using gene-specific PCR amplification technique, and its expressions were analyzed under simulated vernalization at 0–2°C for 0, 10, 20, and 30 d. The gene-specific primers were designed for semiquantitative PCR analysis based on the sequences of the VRN-A1, VRN-B1, and VRN-D1, which were cloned from Zhengmai 9023. The results showed that the genotype of VRN-1 was vrnA1VrnB1vrnD1 with the unique dominant allele in B genome of Zhengmai 9023. Under the treatment of 0 d vernalization, the expressions of VRN-A1 and VRN-D1 were not detected at one-leaf stage, whereas VRN-B1 expressed at a low level and the expressions of the three VRN-1 alleles were all at relative high levels from three-leaf stage to flowering stage. However, under the treatments with 10 to 30 d vernalizaion, the three alleles of VRN-1 gene showed high-level expressions throughout the period from one-leaf to flowering stages.

Transformation of EPSP Synthetase Gene from Allium macrostemon Bunge into Tobacco and Improvement of Resistance in Transgenic Phants

HUANG Li-Hua,JIANG Xiang,LI Bo,LI Yu-Qiang,ZHANG Xue-Wen

Acta Agron Sin. 2009, 35(5):  855-860.  doi:10.3724/SP.J.1006.2009.00855

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EPSPs (5-enolppyruvylshikimate-3-phosphate synthetase) is an important enzyme involved in the synthesis of the aromatic amino acids in all plants, which catalyzes phosphoenolpyruvate and shikimate 3-phophate to form 5-enolpyruvlshimimate-3-phosphate and phosphate. Glyphosate is a chemical with similar structure of phosphoenolpyruvate, which combines enzyme to inhibit the activity of EPSPs, so it is a broad spectrum herbicide to control weeds. Breeding glyphosate tolerance or resistance crops will be an effective way to control weeds. In the study, a gene cDNA (EPSPsA) isolated from Allium macrostemon Bunge was ligated with vector pWM101 to construct a recombinant vector. The recombinant gene was transformed into WS38 via Agrobacterium-mediated way to obtain transgenic tobacco seedlings. Transgenic seedlings were screened with ordinary antibiotics. PCR analysis showed that EPSPsA was successfully integrated into the tobacco genome in all the transgenic seedlings. The result of RT-PCR also validated that EPSPsA was transcripted at mRNA leve1. At 60 d after spraying 200 mg L^-1 glyphosate, the transgenic tobacco plants grew better than the untransformed plants. The average fresh weight of aerial parts in transgenic plants had a significant increase compared with those in untransformed control plants. The average chlorophyll content in transgenic plants was 5.54 mg g^-1, while that in the control only 1.16 mg g^-1. In the treatment with 400 mg L^-1 glyphosate, the untransformed plants died while the transgenic ones grew well in the treatment with 1 000 mg L^-1 glyphosate. These results proved that the EPSPsA can  improve the glyphosate tolerance in tobacco .

Increasing Density of Wheat Genetic Linkage Map with Molecular Makers

LI Yan-Qiu，SU Zhi-Fang，WANG Li-Xin，JI Wei，YAO Ji，ZHAO Chang-Ping

Acta Agron Sin. 2009, 35(5):  861-866.  doi:10.3724/SP.J.1006.2009.00861

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High density genetic linkage map is the groundwork for mapping gene or quantitative trait loci, map-based cloning and marker-assisted selection. To increase the marker density on genetic linkage map of wheat (Triticum aestivum L.), the double haploid (DH) population derived from Jinghua 1/Xiaobai Dongmai and the recombinant inbred lines (RILs) of Nongda 015/Fuzhuang 30 were used in this study. A total of 339 polymorphic markers between the DH lines and 343 polymorphic markers between the RIL lines were detected. Using the DH population, 208 markers were mapped on 21 chromosomes, covering 3 493.6 cM; and using the RIL population, 299 markers were mapped on 34 linkage groups with the average distance of 15.5 cM. The two linkage maps had 56 consistent markers in the similar regions of chromosomes. Using Joinmap 4.0 software, ten linkage groups from the two linkage maps were integrated. This linkage map was composed of 217 markers and covered 956.2 cM of wheat genome with an average distance of 4.4 cM between markers. The proportion of segregation distortion loci was 3.2–55.6% on eight chroosomes. Most markers in this map had the consistent locations with those mentioned in previous report, however, five SSR markers were located on different chromosomes. The results enhance the density of wheat linkage map and provide more information for users.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Starch Gelatinization and Retrogradation Properties under different Basic Fertilizer Regimes and Nitrogen Topdressing at Jointing Stage of Waxy Maize

LU Da-Lei,WANG De-Cheng,JING Li-Quan,HAN Qing,GUO Huan-Fen, et al.

Acta Agron Sin. 2009, 35(5):  867-874.  doi:10.3724/SP.J.1006.2009.00867

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Proper fertilizer managements can improve the starch gelatinization and retrogradation properties of waxy maize (Zea mays L. Ceratina Kulesh). The split-design experiment was conducted using waxy maize cultivar Suyunuo 4 with four main plots subjected to basal fertilizer treatments of N 75 kg ha^-1, N 75 kg ha^-1+K₂O 70 kg ha^-1, N 75 kg ha^-1+P₂O₅ 65 kg ha^-1, and N 75 kg ha^-1+P₂O₅ 65 kg ha^-1+K₂O 70 kg ha^-1, respectively in 2007 and 2008. The three split plots were topdressed with nitrogen of 0, 150, and 300 kg ha^-1 at jointing stage, respectively. Though onset temperature (T_o), peak temperature (T_p) and conclusion temperature (T_c) of native starch and retrogradated starch were affected by fertilizer treatments, the variation was little. No significant effects were observed for basic fertilizer treatments on the enthalpy of gelatinization (ΔH_gel), and for N topdressing treatments on gelatinization range (R) and peak height index (PHI). The R-value was the lowest in the treatment with only N and K in basal fertilizer, and the highest in the treatment with N, P, and K in basal fertilizer. The changes of PHI showed an opposite trend to R. The ΔH_gel was the highest in the treatment with medium N topdressing (150 kg ha^-1). Gelatinized starch became retrograded with lower T_o, T_p, T_c, enthalpy of retrogradation (ΔH_ret), and PHI, as well as wider R. Compared with the treatment of only N applied in basal fertilizer, the percentage of retrogradation and ΔH_ret decreased when P and/or K added in the basal fertilizer. The two indicators were higher in the treatments with N topdressing than without N topdressing. The percentage of retrogradation was positively correlated with ΔH_ret (r = 0.90, P < 0.01) and PHI of retrograded starch (r = 0.41, P < 0.05). ΔH_gel was positively correlated with PHI (r = 0.65, P < 0.01) and ΔHret (r = 0.44, P < 0.05), but negatively correlated with T_c (r = -0.41, P < 0.05). It is recommended to apply balanced fertilization with N, P, and K combining with moderate N topdressing under conditions similar to the experiment to improve gelatinization and retrogradation properties of waxy maize starch.

Drought Tolerance Enhanced by phosphorus Deficitiency in Potato Plants

WANG Xi-Yao,ZHU Tao,ZOU Xue,WANG Ji-Sheng,WANG Mi

Acta Agron Sin. 2009, 35(5):  875-883.  doi:10.3724/SP.J.1006.2009.00875

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Many morphological and physiological adaptations responding to drought or phosphorus (P) deficiency have been reported. But the researches on the relationship between P nutrition and drought tolerance are less, and the results are not consistent. The majority findings indicate that sufficient P nutrition can promote photosynthesis and growth of roots, increase bound water proportion and cell membrane stability and so on, thus enhance the adult plant drought tolerance. But it is found in our preliminary studies that potato grown in low-P environment showed a strong resistance to drought. This experiment aimed to verify and explain this phenomenon in physiological level. A total of 60 lines with 30-day-old Seedlings chosen from two segregating populations of distant-hybridization progenies were cultured in 1/2 MS mineral nutrient solution with two treatments of normal P and without P for 16 d respectively. Then, 8% PEG8000 was used to simulate drought stress for 3 h. Before and after drought stress, the concentrations of proline (Pro), soluble sugar, malonaldehyde (MDA) and the activities of peroxidase (POD) and superoxide dismutase (SOD) were measured, respectively. P deficient treatment increased the number of new roots, but reduced the leaf area and stomatal density. Before drought stress, the Pro and soluble sugar concentrations, POD activity of P deficient plants were increased and reached about 2 times higher compared to P sufficient plants. After 3 h drought stress, plants in P deficient treatment did not wilted, and the soluble sugar, root Pro concentrations, POD and SOD activities were significantly or very significantly higher, but plants in P sufficient treatment showed severely wilting and the MDA, leaf Pro concentrations evidently increased. Therefore, we can conclude that the morphological and physiological changes adapting to P deficiency enhance the drought tolerance of potatoes.

Variation and Distribution of Seed Storage Protein Content and Composition among Different Rice Varieties

ZHOU Li-Hui, LIU Qiao-Quan, ZHANG Chang-Quan, XU Yong, TANG Su-Zhu, et al.

Acta Agron Sin. 2009, 35(5):  884-891.  doi:10.3724/SP.J.1006.2009.00884

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The crude protein contents (PC) in 351 varieties were measured by near infrared spectroscopy (NIRS) and their distribution and classification were analyzed. The results showed that the average value of crude protein content in indica and japonica types were 13.2% and 12.2%, respectively, with an average of 12.42%. The range of those above was 10.8–16.8%, 9.3–17.7%, and 9.3–17.7%, respectively. It elucidated that PC was higher in indica rice than in japonica rice. The huge difference in ratios of varieties (lines) based on their PC showed the genetic disequilibrium between subspecies indica and japonica, for exsample, the ratio of japonica rice with low PC was eight times that of indica rice with low PC. According to the criterion classifying varieties with different protein contents, most of rice genotypes fell into the group with intermediate PC, and there was very small number of varieties with either high or low PC, especially with very high PC in japonica rice. However, we could find some extreme individuals which PC were very high/low, such as those with high PC: forage rice, early maturity varieties and indica-japonica hybrid progenies close to indica in the subspecies of indica, or close to japonica in the subspecies of japonica; and those with low PC: some japonica rice (but the PC not low enough), some overseas germplasms in indica. Thus it was not impossible to find out extreme germplasms on PC from landrace, overseas germplasms or india-japonica hybrid progenies etc., which are fine basic materials in genetic and breeding researchs. From the results of SDS-PAGE analysis of the total seed storage proteins among some representative varieties, we could know that the seed storage protein composition was different among different types of rice genotypes.

Fertilization Process in Flax and Its Performance Time for Each Stage

YANG Hong,SHEN Jia-Heng,LI Wei,DING Jian-Ting,KANG Qing-Hua

Acta Agron Sin. 2009, 35(5):  892-898.  doi:10.3724/SP.J.1006.2009.00892

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The experiment was conducted by means of routine paraffin-embedded sectioning technique to offer some information for its genetic breeding, gene engineering and reproductive biology. The results showed that pollen grains germinated immediately when they were fallen on stigma in self-pollinated flax, then pollen tubes grew in the intercellular space of transmitting tissue of style, entering ovary and growing on the surface of endocuticle of ovary wall, and passing micropore through placenta and funicle. Pollen tube entered one synergid, and released two sperms between egg and central cells. Sperm nucleus and cytoplasm body formed by shucking cytoplasm from sperm. One sperm nucleus entered egg, and another entered the central cell. Fusion of sperm nucleus and egg nucleus was a little slower than that of sperm nucleus and secondary nucleus. Fusion process of male and female nucleoli was observed. The performance time was as follows: Pollen grains germinated very soon on stigma. Pollen tube grew into micropyle about at 4.5 hours after flowering. Pollen tube entered one synergid and released two sperms during about 4.5–5.5 hours after flowering. Fusion of egg-sperm took place in about 5.5–6.5 hours after flowering as well as that of sperm-secondary. Primary endosperm nucleus divided at about 7.5–8.5 hours after flowering. Zygote divided at 12.5 hours after flowering. The dormancy stage of zygote was at about 6.5–12.5 hours after flowering.

Effects of Exogenous ABA and GA on the Main Quality Characteristics of  Grains at Different Positions of Panicle in Rice

DONG Ming-Hui,LIU Xiao-Bin,LU Chun-Quan,ZHAO Bu-Hong,YANG Jian-Chang

Acta Agron Sin. 2009, 35(5):  899-906.  doi:10.3724/SP.J.1006.2009.00899

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Plant hormones play important roles in plant growth and development and yield formation. ABA and GA are two important kinds of hormones controlling rice grain development and filling, but the mechanism of regulating grain quality by them is not understood completely. In order to study and document the influence of ABA and GA on grain quality, the solutions with low concentrations of exogenous ABA (75.7 μmol L^-1) and GA(57.7 μmol L^-1) were sprayed at earlier filling stage. The results indicated that the effects of exogenous hormones at early filling stage on rice quality were great, and varied with exogenous hormone varieties and different grain positions. The exogenous ABA increased the 1000-grain weight (KGW) and head milled rice rate (HMRR), and reduced chalkiness degree (CD); the effect of ABA on grain quality varied with the positions of branch and grain in a rice panicle, which was greater on the later-flowered spikelets than on the earlier-flowered spikelets in the same branch, and on second branch than on primary branch. With spraying exogenous GA, KGW, and HMRR, gel consistence and crude protein content (CPC) were decreased significantly, while CD and amylase content were increased. The effect of spraying GA on KGW and HMRR of the earlier-flowered spikelets was greater than that of the later-flowered spikelets, but it was reversed on CD, AC, and CPC compared with spraying ABA.

Characteristics of Fiber Quality in Cotton Development and Its Regulation by Hormone in Two Natural Colored-Cotton Cultivars

ZHANG Xiang,XIAO Jian,LUAN Na,WANG Yong-Hui,YANG Zhao-Hua,CHEN Yuan, et al.

Acta Agron Sin. 2009, 35(5):  907-913.  doi:10.3724/SP.J.1006.2009.00907

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The brown cotton cultivar Xiangcaimian 2, green cotton cultivar Wanmian 39, and white fiber control cultivar Sumian 9 were used to study the fiber developmental characteristics and the effect of hormones on fiber quality with sampling different stages after anthesis. The results showed that fiber length of the brown and green cotton cultivar was lower than that of control, and that of the green cotton always lower than that of brown cotton. Compared with the control, the fiber strength, fiber micronaire, fiber maturation of natural-colored cotton were lower. The lower fiber length for the green cultivar was due to the less increase during 10 to 30 days post anthesis (DPA), the lower fiber strength, fiber micronaire, fiber maturation of natural-colored cotton were due to the slower growing speed at the pivotal stage. The IAA content at 10 DPA, the ABA content at 30 to 40 DPA in fiber of the two natural-colored cultivars were lower than that of Sumian 9. In comparison with control, in the treatment of applying 20 mg L^-1 GA₃, the IAA content in the fiber of Xiangcaimian 2 and Wanmian 39 at 20 DPA increased by 51.07% and 64.33%, respectively at boll opening stage, and fiber length also enhanced by 8.13% and 13.96%, respectively at boll open stage. The ABA content in fiber in the treatment applying 20 mg L^-1 ABA at 40 DPA increased by 38.96% and 24.40% for Xiangcaimian 2 and Wanmian 39 respectively. The fiber strength, fiber micronaire, fiber maturation also enhanced at the boll opening stage, especially for Wanmian 39. Those results suggest that endogenous hormones affect fiber quality, application of ABA and GA₃ with suitable concentration can increase the content of hormones in the natural-colored cotton fiber and advance the fiber quality, and the effect of different hormones are different.

Effects of Weedy Rice on Yield and Quality and Micro-Ecological Environment in Cultivated Japonica Rice Population

SONG Dong-Ming,MA Dian-Rong,YANG Qing,CHEN Wen-Fu*

Acta Agron Sin. 2009, 35(5):  914-920.  doi:10.3724/SP.J.1006.2009.00914

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Weedy rice WR04-12 and cultivated rice Liaojing 294 were used in field experiment. The results showed that the significant decrease of yield in Liaojing 294 was induced by increasing weedy rice density. The decrease of number of rice panicles and spikelets per panicle, was one of the main reasons causing yield loss of cultivated rice. Milling quality, nutrient quality, and taste quality of cultivated rice decreased with the increasing of weedy rice density, while apparent quality did not show the same trend. The daily minimum temperature and minimum humidity increased in some degree, but the maximum temperature, daily temperature difference, maximum humidity, and daily humidity difference decreased in the cultivated rice population with increasing weedy rice density. The illuminance, at 60 and 90 cm from ground of cultivated rice seems to be decreased with the increase of weedy rice density and that at 30 cm was not influenced by this parameter. As a whole, the weedy rice was a negative effect on micro-ecological environment of cultivated rice population which is the indirect reason of decreasing yield and quality.

Comparison of Rice Plant Types in Northeast Region of China

LI Hong-Yu,HOU Yu-Ming,CHEN Ying-Hua,QUAN Cheng-Zhe,YAN Ping,LIU Meng-Hong，et al

Acta Agron Sin. 2009, 35(5):  921-929.  doi:10.3724/SP.J.1006.2009.00921

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Eighty-one rice cultivars and lines tested in regional trial in Liaoning, Jilin, and Heilongjiang provinces in 2006 and 2007 were used to study the plant-type characteristics and their relationships with yield in Shenyang, Gongzhuling, and Wuchang. The results indicated that the plant-types of most cultivars and lines in northeast region of China were EPT (erect panicle type) or SEPT (semi-erect panicle type) according to PNC (panicle-neck curvature), DPT (dense panicle type) or SDPT (semi-dense panicle type) according to grain density, MPT (middle panicle type) or HPT (heavy panicle type) according to panicle weight and low part panicle superior. Most rice cultivars or lines were CPT (curve panicle type) or SEPT in Heilongjiang, SEPT in Jilin and EPT in Liaoning; semi-dense or loose panicle type, and MPT (middle panicle type) or TPT (thin panicle type) in Jilin and Heilongjiang, and dense panicle type and HPT(heavy panicle type) in Liaoning. Large vascular bundles in neck (LVBN), small vascular bundles in neck (SVBN),large vascular bundles in the second internode (LVBS) and small vascular bundles in the second internode (SVBS) ranked as Liaoning＞Jilin＞Heilongjiang; length and width of the top three leaves of Liaoning cultivars were the largest, but basic angle less than that of Jilin and Heilongjiang. LVBN, SVBN, LVBS, and SVBS were very positively correlated with primary branches, primary branch grains, secondary branches, secondary branch grains, and secondary branch grain rate, but negatively correlated with seed-setting rate and 1000-grain weight of primary branch and secondary branch. Cluster analysis showed that most cultivars in northeast of China were high-yielding or mid-yielding. With a tendency of more vascular bundles, longer and wider the top three leaves, higher plant, larger biomass and smaller angle of leaf.

Seedling Standing Characteristics and Technology of No-tillage and Cast Transplanting Rice

WU Jian-Fu,PAN Xiao-Hua,SHI Qing-Hua

Acta Agron Sin. 2009, 35(5):  930-939.  doi:10.3724/SP.J.1006.2009.00930

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The field experiment and pot experiment was conducted during 2005–2006 to study the seedling standing characteristics and technology of no-tillage cast transplanting rice. The results showed that no-tillage seedling broadcasting cultivation was beneficial to root growth, seedling standing early and fast, and shoot growth under the conditions of appropriate low water layer (around 1 cm), using younger seedlings, increasing appropriate N at the early growth stage, appropriate straw incorporation (1 200 kg ha^-1), dry land seedling raising on plastic trays and spraying paclobutrazol at 2.5 leaf and soaking seed by α-naphthylacetic acid. The standing speed of non erect seedlings had great relation to seedling age, short seedling age quickened seedling standing and promoted rice growth. There were close correlations between average root number and root length per plant, soluble sugar, total N content ofshoot and seedling standing after broadcasting seedlings with no-tillage. The results provided a reference for popularizing and applying the technology of no-tillage and cast transplanting rice in the future.

RESEARCH NOTES

Application of E.arundinaceus cDNA Microarray in the Study of Differentially Expressed Genes Induced by U.sitaminea

QUE You-Xiong,XU Li-Ping*,LIN Jian-Wei,XU Jing-Sheng,ZHANG Ji-Sen,ZHANG Mu-Qing

Acta Agron Sin. 2009, 35(5):  940-945.  doi:10.3724/SP.J.1006.2009.00940

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RNAs of sugarcane leaves with (treatment) or without (control) the infection of U. scitaminea were extracted, subjected to hybridization of cDNA microarray based on E. arundinaceus cDNA sequence and further validated by Real-time qPCR. There were about 101 differentially expressed ESTs (with ratio value ≥2.0 or ≤0.5) among 3 860 genes sets in a microarray plate, with 55 up-regulated, and 46 down-regulated by U. scitaminea. After sequencing and redundant sequences elimination, we totally obtained 36 unique ESTs up-regulated after the infection of U. scitaminea. Among them, 22 were involved in several metabolism pathways, such as photosynthesis, ion transport and nucleotide metabolism, as well as some genes related to transcription factors, proteins synthesis and modulation, and cellular signal transduction. And the function of the 14 remaining ESTs was unknown. In conclusion, the molecular mechanism of sugarcane smut resistance is complex. This investigation would provide an understanding for differentially expressed genes induced by U. scitaminea and set a mode for the systematic research on molecular mechanism of sugarcane responses to biotic and abiotic stress.

Effects of Endophytic Fungus on Sugar Content and Key Enzymes Activity in Nitrogen and Sugar Metabolism of Sugar Beet(Beta vulgaris L.)

SHI Ying-Wu,LOU Kai,LI Chun

Acta Agron Sin. 2009, 35(5):  946-951.  doi:10.3724/SP.J.1006.2009.00946

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We investigated the agronomic traits and determined the activity of key enzymes in sugar and nitrogen metabolisms in beet leaf and root with treatments of by using Plectosphaerella cucumerina F11 solution seed soaking, leaf spraying and root watering. The results showed that the strain F11 obviously promoted growth of beet seedlings, the effect with the better in root watering treatment than in others. the leaf fresh weight,content of chlorophyll, fresh weight per root, sugar content and sugar yield of beet increased significantly (P<0.05) by 66.67%, 47.42%, 6.96%, 17.46%, and 25.63%, respectively; F11 enhanced evidently the activities of key enzymes in sugar and nitrogen metabolisms of beet during whole growth period. The changes of activities of nitrate reductase (NR) and glutamina synthetase (GS) presented the curves of M-shape and parabola shape, respectively. The changes of activities of sucrose synthase (SS) and sucrose phosphate synthase (SPS) in beet displayed the single peak curve. The synthesis activity was much higher than the decomposition activity for SS in roots of beet at late growth stage. The activity of SPS was higher at early growth stage than at late growth stage, and the activity of SPS was the highest during phyllome formation period. It was concluded that the strain F11 not only enhanced activities of key enzymes in sugar and nitrogen metabolisms of beet, but also promoted the growth, yield and sugar accumulation of beet.

Subcellular Localization and Genetic Polymorphism of Isoform of Starch Branching Enzyme（SBE IIb）in Wheat Grain

ZHAO Fa-Mao,CAI Rui-Guo,BI Jian-Jie,XIAO Jun,WANG Xian-Ze

Acta Agron Sin. 2009, 35(5):  952-957.  doi:10.3724/SP.J.1006.2009.00952

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To elucidate subcellular localization and genetic polymorphism of SBE IIb, the isoform of starch branching enzyme (SBE), in wheat grain and make insight into molecular mechanism of amylopectin biosynthesis. We identified the differences of SBE IIb among 70 wheat varieties using SDS polyacrylamide gel electrophoresis (SDS-PAGE), recovered SBE IIb from polyacrylamide gel and determined its enzymatic activities. The expression levels of SBE IIb were examined during grain-filling period. The result indicated that starch granule-bound protein SGP-2, was granule-associated SBE IIb with molecular weight of 85 kD. It possessed SBE activity when SDS was removed by acetone precipitation, which reached the highest activity at the 21th day after anthesis. SBE IIb expressed at early developing stage of wheat grain and expression quantity exhibited differences in different developing periods. Notably, the expression profile of SBE IIb showed no differences among 70 varieties.

Mapping Unequal Crossing Over Hotspot Region of Simple sequence Repeat in Maize

TANG Ji-Hua,MA Xi-Qing,TENG Wen-Tao,YAN Jian-Bing,DAI Jing-Rui,LI Jian-Sheng

Acta Agron Sin. 2009, 35(5):  958-961.  doi:10.3724/SP.J.1006.2009.00958

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The polymorphism of simple sequence repeat (SSR) in biological genome is one result of unequal crossing over for homologous chromosomes; therefore it has theoretical importance in clarifying the hotspot regions of unequal crossing over. A set of recombinant inbred lines (RILs) population that derived form an elite hybrid Yuyu 22 was used in this study, its genetic components of the population was analyzed by means of SSR analysis, and 40 unequal crossing over SSR markers were found. The frequency of the unequal crossing over in the RIL population was 0.34–14.63%, with 10^-2–10^-1 frequency per generation, and the (AG)n repeat SSR markers accounted for 58.3%. There were 31 unequal crossing over markers locating on 11 chromosomal hotspot regions, distributing on 10 chromosomes except for chromosome 9, including two unequal crossing over hotspot regions each in chromosomes 3 and 5.

Comparison of Starch，Protein Accumulation and Amyloplast Development in Wheat Cultivars with Strong ，and Weak Gluten

MENG Xiu-Rong,XIONG Fei,KONG Yu,CHEN Yong-Hui,MA Shou-Bao,LU Wei,WANG Zhong

Acta Agron Sin. 2009, 35(5):  962-966.  doi:10.3724/SP.J.1006.2009.00962

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Wheat cultivars Yannong 19, Yangmai 16, and Ningmai 13 responsible for strong-, medium-, and weak-gluten types respectively, were used to compare the accumulations of starch and protein during grain filling as well as the amyloplast components in mature grains. The contents of starch, amylose, and amlylopectin in grains showed similar dynamic changes in the three cultivars, and ranked as Ningmai 13>Yangmai 16>Yangnong 19. The accumulation quantities of starch, amylose, and amlylopectin varied in trends of S-curve during the grain-filling period, and the accumulation rate was in a parabola. Among the three cultivars, Yangnong 19 possessed the highest quantity and rate in the accumulation of starch and its components, and Ningmai 13 the lowest. The changes of protein content during grain filling in three cultivars all presented V-curves with the highest content in Yannong 19 and the lowest content in Ningmai 13. During the development of grains, large amyloplast formed in earlier period and small amyloplast was observed mainly in later period. The quantity of large amyloplast in the three cultivars showed Yannong 19>Yangmai 16>Ningmai 13, whereas those of small amyloplast randed in the opposite direction. In endosperm cells of mature grain, large amyloplast was more than small amyloplast in Yannong 19, and the amyloplasts were in compact structures. In Ningmai 13, the opposite status was observed.