Genetic diversity of taro, Colocasia esculenta (L.) Schott, in Southeast Asia and the Pacific

The genetic diversity of 255 taro (Colocasia esculenta) accessions from Vietnam, Thailand, Malaysia, Indonesia, the Philippines, Papua New Guinea and Vanuatu was studied using AFLPs. Three AFLP primer combinations generated a total of 465 scorable amplification products. The 255 accessions were grouped according to their country of origin, to their ploidy level (diploid or triploid) and to their habitat cultivated or wild. Gene diversity within these groups and the genetic distance between these groups were computed. Dendrograms were constructed using UPGMA cluster analysis. In each country, the gene diversity within the groups of wild genotypes was the highest compared to the diploid and triploid cultivars groups. The highest gene diversity was observed for the wild group from Thailand (0.19), the lowest for the diploid cultivars group from Thailand (0.007). In Malaysia there was hardly any difference between the gene diversity of the cultivars and wild groups, 0.07 and 0.08, respectively. The genetic distances between the diploid cultivars groups ranges from 0.02 to 0.10, with the distance between the diploid accessions from Thailand and Malaysia being the highest. The genetic distances between the wild groups range from 0.05 to 0.07. First, a dendrogram was constructed with only the diploids cultivars from all countries. The accessions formed clusters largely according to the country from which they originated. Two major groups of clusters were revealed, one group assembling accessions from Asian countries and the other assembling accessions from the Pacific. Surprisingly, the group of diploid cultivars from Thailand clustered among the Pacific countries. Secondly, a dendrogram was constructed with diploid cultivated, triploid cultivated and wild accessions. Again the division of the accessions into an Asian and a Pacific gene pool is obvious. The presence of two gene pools for cultivated diploid taro has major implications for the breeding and conservation of germplasm. (Résumé d'auteur