Analysis of genetic diversity and population structure in Cambodian melon landraces using molecular markers

Abstract Genetic diversity of Cambodian melon was evaluated by the analysis of 12 RAPD and seven SSR markers using 62 accessions of melon landraces, and compared with 231 accessions from other areas for genetic characterization of Cambodian melon. Among 62 accessions, 56 accessions were morphologically classified as small-seed type whose seed length was shorter than 9mm as like groups Conomon and Makuwa. Gene diversity of Cambodian melon was 0.228 which was equivalent to those of groups Conomon and Makuwa and smaller than those of Vietnamese and Central Asian landraces. Phylogenetic tree constructed from genetic distance matrix classified 293 accessions into three major clusters. Small-seed type accessions from east and southeast Asia formed clusters I and II, which were distantly related with cluster III consisted of large-seed type melon from other areas. All of Cambodian melon belonged to cluster I except three accessions, along with those from Thailand, Myanmar, Yunnan (China) and “Dua thom” from northwestern part of Vietnam, indicating genetic similarity in these areas. In addition, Cambodian melon was not differentiated among geographical populations. Conomon and Makuwa were classified into cluster II, together with melon groups from plain areas of Vietnam. The presence of two groups of melon in southeast Asia was also indicated by population structure and PCO analysis. These results indicated close genetic relationship between Cambodia and the neighboring countries, and suggested that Cambodian melon is not directly related with the establishment of Conomon and Makuwa.