First genetic maps and QTL studies of yield traits of taro (Colocasia esculenta (L.) Schott)

The paper presents the first taro (Colocasia esculenta L. Schott) genetic maps. Taro is an important vegetatively propagated root crop species in most subtropical areas. It is an allogamous and protogynous species with a basic chromosome number of x = 14. Two F-1 progenies of 123 and 100 individuals obtained from crosses between local cultivars from Vanuatu (VU101 x VU104 and VU373 x VU314) were chosen for this study. Both genetic maps contained 169 markers, mainly AFLPs and 8 SSRs, and were characterised by a high density of markers and a short map length. The maps had 14 and 18 linkage groups (LG) respectively and were not completely saturated. Twenty-four markers were identified across the two progenies and a good co-linearity was observed for the majority of these markers. A QTL detection study was conducted on both progenies with 91 and 89 individuals respectively. Several putative QTLs were identified for corm yield and corm dimensions (which were highly correlated traits) whereas no QTL was detected for dry matter content. This result was relatively unexpected since dry matter content was a more highly heritable trait than corm yield or corm dimensions. A major dominant gene, responsible for the yellow colour of the corm flesh, was also identified. Further mapping studies on taro should include a larger number of SSR markers, larger progenies should be created and other important traits related to yield and eating quality should be included in the QTL analyses.