中国小麦品种资源Glu-1位点组成概况及遗传多样性分析

 分析了 5 12 9份中国小麦初选核心种质样品HMW GS的组成情况 ,其中地方品种 345 9份、育成品种(系 ) 16 70份。这些材料作为初级核心种质基本代表了保存在国家长期库中的普通小麦种质资源的遗传多样性 ,覆盖了中国小麦栽培的 10大生态区。总体来看 ,在Glu A1、Glu B1和Glu D13个位点上的主要等位变异分别为null、7+8和 2 +12。育成品种中 1、7+9、14 +15、5 +10和 5 +12亚基 (对 )的频率比地方品种有很大的提高。在Glu 1位点上 ,地方品种与育成品种的遗传丰富度差异甚微 ,但育成品种的遗传离散度指数却显著高于地方品种。在 3个位点中 ,Glu B1位点的多样性最丰富 ,其次为Glu D1位点 ,Glu A1位点的多样性最差。从生态区来讲 ,地方品种变异类型最丰富的 3个大区是黄淮冬麦区、西北春麦区和西南冬麦区 ;选育品种最丰富的 4个大区是西南冬麦区、黄淮冬麦区、长江中下游冬麦区和北部冬麦区。由于广泛的引种、杂交、选择以及亲本选配中的偏爱 ,造成许多生态区遗传离散度指数高低与遗传丰富度出现相矛盾的现象 ,这点在长江中下游冬麦区材料中表现尤为突出。育成品种与地方品种间遗传分化系数分析表明 ,现代引种和杂交育种使我国小麦品种“群体”遗传组成和结构发生了质的变化。

Allelic Variation and Genetic Diversity at Glu-1 Loci in Chinese Wheat (Triticum aestivum L. ) Germplasms

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.