An analysis about genetic basis of cotton cultivars in China since 1949 with molecular markers

The diversity of 166 cotton cultivars(cult.) including 159 upland( G.hirsutum L) and 7 island( G.barbadense L) ones planted mainly in China since 1949 was explored by RAPD,genetic distance(GD) and cluster analysis.The correlation coefficients between Nei's GD of RAPDs and two groups of phenotype data's Euclidean distances (UD) were 0 6445(n=1770) and 0 7078(n=7140),which indicated that RAPD could be used to explore genetic diversity among cotton cultivars in China.The genetic basis of cotton cultivars in China was studied by comparison among different cotton species,different cultivar types,different history periods,different growing regions and different sources.The results showed as follows:within cotton cultivars planted in China,the genetic basis of island cotton cultivars was narrower than that in upland ones;the genetic basis of cultivars released in China since 1949 was narrower than that of introduced ones from outside of China;the genetic basis of hybrids was narrower than that of conventional cultivars(Conv.Cult.);the genetic basis of upland cultivars after 1980 was narrower than that in 1970's;the genetic basis of cultivars in Changjiang cotton region was narrower than that of Huanghuai cotton region,northwestward cotton region was the narrowest.From which some strategies for breeding,especially for the methods of widening the genetic basis of China cotton cultivars,could be understood and withdrawn.