海拔及细胞质背景对水稻测交群体遗传分化的影响

摘要

温度是导致水稻(Oryza sativa L.)遗传分化的一个重要环境因素,而海拔是导致环境温度差异的一个重要的地理因素.水稻的雄配子即花粉粒的活性极易受环境温度的影响.研究用来自云南2 670 m海拔的粳稻地方品种小麻谷与具籼稻细胞质背景的籼粳交后代品系南34正反交产生的F1,然后将其分布种植在海拔高低相差达1 800m的4个海拔点并与育性稳定的1个滇Ⅰ型细胞质不育系杂交产生了8个测交群体,用SSR标记检测发现海拔因素和细胞质背景都对测交群体的遗传分化产生了影响.结果表明:同一海拔产生的正反交群体(合系42A//小麻谷/南34)间的遗传多样性具有比较明显的差异.正交组合F1(小麻谷×南34)在1 860m的海拔产生的群体的遗传多样性最高,在1 600m的海拔产生的群体的遗传多样性最低.在反交组合F1产生的群体中,群体的遗传多样性随产生群体海拔(400 m海拔除外)的升高而降低.利用Nei's遗传距离评价各群体间的遗传分化,正反交组合F1产生测交群体间的遗传分化均高于同一组合在不同海拔下产生的测交群体之间的遗传分化,同一组合在4个海拔产生的测交群体间的遗传分化总体趋势是随海拔差异的增加而增大.研究证实了环境温度差异及细胞质背景导致F1产生的雄配子基因型发生选择,导致雄配子基因型的遗传比例偏离孟德尔规律,影响其后代群体的遗传多样性和遗传分化.%Temperature, changes along with altitude, is one of key ecological factors causing genetic differentiation and affecting viability on male gametes or pollen grains of rice. In this research, reciprocal F1 hybrids were produced by cross between a cv. Xiaomagu, a cold tolerant japonica landrace collected at 2 670 m altitde with cv. Nan 34, which was derived from mult-crosses between indica and japonica. 8 populations were developed by pollinating a cytoplasmic male sterile(CMS)line of Dian type 1 with the reciprocal F1S grown at four locations varied at altitudes from 400 to 2 200 m. Genetic diversity and genetic differentiation of the test-cross populations caused by variations of altitudes and cytoplasm backgrounds, were studied based on the SSR markers. The results showed that the genetic diversity of the reciprocal cross populations(Hexi42A//Xiaomagu/Nan34)produced at the same altitude were obvious differences. The genetic diversity of the test-cross population generated from the orthogonal combination of Fi(Xiaomagu/Nan34)was the highest at 1 860 m altitude, and that was the lowest at the 1 600 m altitude, while in the populations of anti-crosses F1, the genetic diversity reduced along with the altitude get higher(400 m except). The genetic differentiation of the populations, evaluated by Nei's genetic distance, were higher in which generated by reciprocal cross F1 than that from the same combination at different elevations. The general trend of the genetic differentiation of the test-cross populations, which produced by the same combination at four locations, is increased along with the altitude get higher. This study confirmed that the cytoplasmic background and the temperature led to the selection of F1 Androgamete genotype, which result in the deviation of male gamete genotypes proportion from Mendelian fashion, eventually affect genetic diversity and differentiation in their derived populations.