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《Scientia Agricultura Sinica》 2002-11
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Allelic Variation and Genetic Diversity at Glu-1 Loci in Chinese Wheat (Triticum aestivum L.) Germplasms

ZHANG Xue yong, PANG Bin shuang, YOU Guang xia, WANG Lan fen, JIA Ji zeng, DONG Yu chen (Institute of crop Germplasm Resources, Chinese Academy of Agricultural Sciences / Key Laboratory of Crop Germplasm and Biotechnology, Ministry of Agriculture, Beijing 100081)  
Wheat processing quality is greatly influenced by seed proteins especially the high molecular weight glutenin subunit (HMW GS) components, low molecular weight glutenin subunit (LMW GS) components and gliadin components. Genes encoding the HMW GS and LMW GS components were located on the long arms and the short arms of homoeologous group 1 chromosomes, respectively. HMW GS components in 5 129 accessions of wheat germplasms including 3 459 landraces and 1 670 bred varieties were analyzed systematically. These accessions were chosen as candidate core collections to represent the genetic diversity of Chinese common wheat (Triticum aestivum) germplasms documented and conserved in the National Gene Bank. These candidate core collections covered the 10 wheat production regions in China. In the whole country, the dominating alleles on Glu A1, Glu B1 and Glu D1 are Glu A1b (null), Glu B1b (7+8), and Glu D1a (2+12), respectively. Obvious difference between landraces and modern varieties is the dramatic frequency increase of alleles Glu A1a (1), Glu B1c (7+9), Glu B1h (14+15), Glu D1d (5+10) and allele cording 5+12 subunits in the later ones. The difference in genetic richness between the landraces and the bred varieties at Glu 1 is small, which is 28 and 30, respectively. However, the genetic dispersion index (Simpson index) based on allelic variations and their frequency at Glu A1, Glu B1 and Glu D1 suggested that the modern varieties have much higher genetic diversity than the landraces. This revealed that various isolated mechanisms (such as auto gamous nature, low migration because of undeveloped transposition system) limited the gene flow and exchange among populations of the landraces, which led up to some genotypes localized in very small areas. Modern breeding has strongly promoted gene exchanges and introgression between populations and previous isolated populations. Of the three loci, Glu B1 has the highest genetic diversity, then Glu D1, while Glu A1 always keeps the lowest genetic diversity. For the landraces, the three regions with the highest allelic richness are Huanghuai Winter Wheat Region, Northwest Spring Wheat Region and Southwestern Winter Wheat Region. For the bred varieties, the highest allelic richness existed at Southwest Winter Wheat Region, Huanghuai Winter Wheat Region, Low Middle Branch Winter Wheat Region of Yangtze River. Introduction and utilization of foreign varieties in cross breeding has had great effects on the allelic components and frequency of the three loci, which greatly affected the genetic dispersion index. This has made the "population" of modern varieties quite different from that of the landraces.
【Fund】: 国家重点基础研究项目 (G19980 10 2 0 2 )
【CateGory Index】: S512.1
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