【作者】 任民；

【导师】 荣廷昭； 曹墨菊； 杨庆文；

【作者基本信息】 四川农业大学 ， 作物遗传育种， 2005， 硕士

【摘要】 本研究采用25个微卫星位点研究了广西壮族自治区贺州、崇左、防城港3市8个居群301份普通野生稻材料的遗传多样性和遗传结构,主要结果如下: 1、桂东南地区普通野生稻遗传多样性较为丰富,平均等位基因数A=10.24,有效等位基因数Ae=5.02,平均期望杂合度He=0.76,实际观察杂合度Ho=0.48。在居群水平上,平均期望杂合度He的变化范围从0.28(居群SB)到0.58(居群YJ);实际观察杂合度Ho的变化范围从0.22(居群SB)到0.58(居群DP);平均等位基因数A的变化范围从2.04(居群SB)到5.20(居群TJ);有效等位基因数Ae的变化范围从1.53(居群SB)到2.99(居群TJ)。除居群SB与YL的遗传多样性相对较低以外,其它居群都有较高水平的遗传多样性。实地考察发现,供试居群原生境周围均有栽培稻种植,栽培稻与野生稻间的基因交流可能是该地普通野生稻遗传多样性较高的原因之一。 2、供试居群遗传结构分析表明,总的遗传变异中有35%存在于居群间(Fst=0.34),遗传变异主要存在于居群内。研究还发现大多数居群偏离了Hardy-Weinberg平衡且表现杂合体不足(Fis=0.27,Fit=0.48)。根据固定指数(F=0.57)计算出的异交率(t=0.28)表明,桂东南地区普通野生稻的繁育系统是包括无性生殖和有性生殖在内的典型的混合繁育系统,且其有性生殖中自交和异交都占较大分量。 3、Nei无偏遗传一致度和遗传距离,聚类分析和主坐标分析计算及结果表明,居群YL与QT间遗传距离D最大(D=1.50),居群DP与DT间遗传距离D最小(D=0.23);居群DP与DT间遗传一致度I最大(I=0.78),居群YL与QT间遗传一致度I最小(I=0.22)。居群SB、YL和YJ聚为一类,居群DP和DT聚为一类,其余三个居群各自成为一类。表明居群SB、YL和YJ遗传关系比较近,而居群DP和DT遗传关系较近,且与其它居群遗传距离较远;除居群DP与DT的个体有交叉外,其它居群间遗传分化较明显,并推测居群DP与DT可能来源于同一个大群落。 4、桂东南地区普通野生稻遗传多样性与纬度间有一定的相关性(r=0.7707,P<0.05),随着纬度的升高,居群的遗传多样性逐渐降低。“距离—隔离”模型检测后发现,虽然桂东南地区从整体上并不符合该模型,但是在较小的范围内(小于100km),居群间的遗传分化与该模型相符。进一步研究发现,在桂南的五个居群中,更多还原

【Abstract】 To estimate genetic diversity of Oryza rufipogon Griff, in Southeast region of Guangxi in China, a total of 301 individuals from 8 natural populations in Hezhou City, Fangchenggang City and Chongzuo City were analyzed using 25 microsatellites loci. The results are as follows:A moderate high level of genetic diversity was obtained at population levels. The overall number of alleles (A) was 10.24. The overall effective number of alleles (Ae) was 5.02. The overall expected heterozygosity (He) and observed heterozygosity (Ho) was 0.76 and 0.48. Most populations have high level of genetic diversity except population SB and population YL. Gene flow between wild rice and cultivated rice might be the reason for the high level of genetic diversity of O.rufipogon, because found all O.rufipogon populations in this study were surrounded by cultivated rice.A moderate genetic differentiation (Fst=0.35) was found among the populations, suggesting that 35% genetic variation existed among the populations. Furthermore, microsatellite showed less deviation from Hardy-Weinberg expectation and a slight deficiency of heterozygotes within and among populations (Fis=0.27, Fit=0A8). And an estimate of the outcrossing rate (t=0.46) suggested that the species has a typical mixed-mating system.The genetic relationship among populations was studied by Nei unbiased genetic coefficient, Nei unbiased genetic distance, clustering analysis and principal coordinate analysis (PCO). Population DP and DT have the nearest genetic relationship (D=0.23, I=0.78); population YL and QT have the farthest genetic relationship (Z)=1.50, I=0.22). All the populations were divided into 5 clusters. Population SB, YL and YJ clustered together and had a close relationship; Population DP and population DT also clustered together but several individuals of these two populations mixed each other. Thereforepopulation DP and DT maybe derived from one larger population.The populations from south region of Guanxi fit the "Isolation-Distance" model well and a special pattern of distribution of the genetic diversity was found, presuming that the populations from south region of Guangxi distributed along a same water system. Meanwhile, the correlation coefficient (r=0.77 P<0.05) between the genetic diversity of O rufipogon populations and the latitude indicated that with the increasing of latitude the genetic diversity of O.rufipogon reduced.Together with the field investigation and the pattern of genetic variation of natural populations of O.rufipogon from Southeast region of Guangxi, it could be suggested that populations of QT, YJ, TJ be given priority for in-situ conservation and population SB be given for ex-situ conservation.更多还原