Breeding and selection of taro (Colocasia esculenta) for improved disease‐resistance in Hawaiʻi

Abstract

Societal Impact Statement Taro is a root crop with wide geographic range and high cultural significance to Indigenous peoples of Hawaiʻi and the Pacific. Taro Leaf Blight (TLB) is a worldwide disease of taro, and Hawaiian taro varieties exhibited little resistance to it. To improve TLB‐resistance, conventional breeding was conducted by hand‐pollination. Out of ~3500 taro seedlings, 18 varieties were selected and evaluated under non‐flooded conditions at four locations in Hawaiʻi over 5 years. Four varieties were identified as high yielding and disease‐resistant. Further, to prevent confusion of new taro varieties with traditional Hawaiian taro, we developed DNA fingerprints to differentiate them. Taken together, these results have provided information regarding new plant material and new tools for those interested in conservation and breeding across the Pacific. Summary Breeding and evaluation of taro (Colocasia esculenta (L.) Schott) was conducted in Hawaiʻi to increase resistance to Taro Leaf Blight (TLB), caused by oomycete pathogen Phytophthora colocasiae Racib., while maintaining high yields and desirable eating qualities. When breeding Indigenous crops such as taro, it is important to consider issues of Indigenous, intellectual property rights. In response to concerns by cultural practitioners about potential confusion of new taro genotypes with traditional landraces, we also sought to develop DNA fingerprints using single nucleotide polymorphisms (SNPs) to identify the new genotypes. Conventional breeding of taro was conducted by hand‐pollination of Hawaiian taro landraces with sources of TLB‐resistance from multiple countries. The most promising lines were multiplied and evaluated under upland (i.e., non‐flooded) conditions on four major Hawaiian Islands over 5 years. DNA was extracted from these new genotypes, analyses of SNPs conducted, and results compared to those of traditional Hawaiian landraces. Bayesian yield analysis of these multi‐year and multi‐location trials identified taro genotypes 1016‐003, 1016‐019, 1024‐215, and 1005‐084 as producing twice the fresh weight corm yield as control “Maui Lehua” and exhibiting disease‐resistance across years and environments. DNA fingerprints of new genotypes were able to differentiate them from traditional Hawaiian landraces that make up a portion of their parentage. Conventional breeding of taro in Hawaiʻi and multi‐year, multi‐location field trials have resulted in high yielding, disease‐resistant genotypes that maintain desirable qualities of some traditional Hawaiian landraces. DNA fingerprints of these new genotypes distinguish them from these traditional landraces, helping to preserve heritage germplasm.