Identification of Superior Germplasm and Development of Genetic Resources for Apios americana: A Potential New Legume Crop

Changing climatic conditions coupled with a growing world population has increased interest in studying alternative crops that are adapted to a range of climatic conditions and possess high nutritional benefits. We believe that Apios americana, a phaseoloid legume, has a great potential to serve as such a new food crop. Apios is well-adapted to the diverse climatic conditions of the central and eastern USA and southeastern Canada with a capacity to withstand prolonged flooding and moderate drought. Apios produces tubers that are rich in both starch and protein (~16%; 3X to 4X that of Solanum tuberosum). Apios is now cultivated as a food crop in Japan and South Korea, because of its nutritional benefits. In the present study, an Apios breeding collection containing 53 genotypes was phenotyped in Iowa, Virginia and Pennsylvania. Six elite genotypes with an average estimated yield of ~16.7 t/ha - on par with other conventional tuber crops have been identified. Fourteen phenotypic descriptors, including both aboveground and belowground traits, for use in future field trials have been established. Also generated is a high-quality reference transcriptome assembly, comprising 48,615 contigs (single isoforms) with an N50 value of 1,863 bp and an average contig length of 1,173 bp together with an expression atlas using six different tissues. Recent transcriptome sequencing of the leaf tissue from 58 genotypes has indicated high levels of heterozygosity in the breeding collection and generated thousands of single nucleotide polymorphism markers for genetic characterization and association analysis