Analysis Of Genetic Diversity Among Sweetpotato In Hunan

The genetic diversity of sweetpotato was analyzed by morphological and molecular (AFLP,SSR and RAPD) markers.A total of 61 accessions,including 27 modern cultivars and 34 landraces. Modern cultuvars included 16 acceccions,among Hunan 11 species,Jiangsu 3 species and Sichuan 2 species; 13 varieties of foreign species,including Brazil 1,2 varieties of the Philippines,Malaysia,1 species,1 variety of Mali,the United States 4 copies of varieties,varieties in Nigeria 1,3 Japanese varieties.Landraces were 32 domestic varieties,including Hunan 20 varieties,Guangdong 6 varieties,Fujian 2 varieties,Chongqing 1 varieties and Hubei lvarieties.The main results were as follows:1.Sixty-one sweetpotato accessions were distinguished clearly based on morphological characteristics,including plant type, mature leaf shape,mature leaf color,leaf vein color,base vein color and stem color.lt was showed that sweetpotato modern cultivars and landraces possessed a high level of phenotypic differences.The genetic distance among modern cultivars and landraces in Hunan was large.2.Using 12 AFLP primer pairs,12 SSR primer pairs and 20 RAPD primers,324,110 and 153 polymorphic bands with an average of 27,9.2 and 7.6 bands per primer (pair) respectively,were amplified among 61 materials.AFLPs were better than SSRs and RAPDs in terms of the number of polymorphic bands and the experimental stability.3.The UPGMA cluster analysis based on AFLP,SSR and RAPD markers classified the 61 accessions into 6 groups. The first group and the three group included most varieties:the first group had 38 species, of which 20 were landraces and 18 were modern cultivars; The three group had 17 species, of which 10 were landraces and 7 were modern cultivars; Lian 73-21-3 and Qiyanghuangxinshu of Hunan landraces were grouped together for the two, the rest were grouped into the group I and group III; TiB10 in Nigeria and Siam Red in Malaysia of modern cultivars were grouped separately into the IV group and V; the VI group was Centennial in the United States and Ximengl in Brazil of modern cultivars.4.The genetic distance between modern cultivars and landraces in Hunan revealed by AFLPs,SSRs and RAPDs differed greatly,being 0.3778-1.0000,0.2308-1.0000 and 0.0588-0.6842,respectively,with the mean genetic distances of 0.7278,0.5443 and 0.2793,respectively. These results supported the viewpoint that accessions in Hunan were highly genetic differences. The genetic distance of landraces in Hunan revealed by AFLPs,SSRs and RAPDs were 0.6537,0.5362 and 0.2955; The genetic distance of modern cultivars in Hunan revealed by AFLPs,SSRs and RAPDs were 0.7075,0.4583 and 0.2951, it was then AFLP＜GDMC AFLP,GDL SSR＞GBMCSSR,GDLRAPD＞GDMC RAPD。5.Based on the 3 molecular markers,the genetic distance between landraces and modern cultivars in Hunan was 0.2941-0.8644,mean 0.5038.The mean genetic distance from different lands of landraces and modern cultivars were calculated by the three molecular markers respectively, the landraces from Hunan and Guangdong had the highest genetic distance.The modern cultivars from Hunan and Malaysia had the highest genetic diatance.Thus,the utilization of these lands should be emphasized in Hunan sweetpotato breeding.