2017 ASHS Annual Conference

Taro, Colocasia esculenta, is one of the world’s oldest root crops and of particular economic and cultural significance in Hawai‘i, where historically more than 150 different cultivars were grown. We developed a genome-wide set of more than 2000 single nucleotide polymorphism (SNP) markers from 70 cultivars of Hawaiian, South Pacific, Palauan, and mainland Asian origins, with several objectives: (a) determine phylogenetic relationships between Hawaiian and other Pacific cultivars, (b) shed light on the history of taro cultivation in the Pacific, and (c) study the genetic basis of morphological traits. We found that almost all existing Hawaiian taro cultivars fall into five monophyletic groups that are largely consistent with the traditional Hawaiian classification based on morphological characters leaf shape and petiole color. Genetic diversity was greater between than within groups. Population structure analyses indicate that the diversification of taro in Hawai‘i most likely occurred by a combination of frequent somatic mutation and occasional hybridization. Unexpectedly, the South Pacific cultivars were found nested within several groups of Hawaiian taros, which suggests that the origin of taro groups identified here preceded the colonization of Hawai‘i, and that early Polynesian settlers brought cultivars from different groups with them. In the absence of a genome sequence, this marker set may also provide a valuable resource to obtain a genetic linkage map and study the genetic basis of phenotypic traits relevant to taro breeding, including disease resistance.