Genotype-by-sequencing of global hyacinth bean (Lablab purpureus) collections provides genomic resources for crop conservation and improvement

Abstract

Hyacinth bean (Lablab purpureus (L.) Sweet), commonly known as lablab, is an underutilized legume with potential for improving food and nutritional security in smallholder farming systems. Although it is adapted to low-input and drought conditions, genetic improvement of lablab is constrained by limited knowledge of its genetic diversity, despite extensive germplasm collections. Moreover, additional diversity maintained in farmers’ fields is currently not well documented or conserved. This study assessed the genetic diversity and population structure in a global panel of 281 lablab accessions, including newly collected farmer cultivars from Tanzania. Genotype-by-sequencing yielded 15,125 high-quality single nucleotide polymorphisms (SNPs). Observed heterozygosity exceeded expected heterozygosity, suggesting partial outcrossing in this predominantly self-pollinating species. The bimodal distribution of individual heterozygosity, with two peaks corresponding to accessions exhibiting low (< 15%), and high (> 15%) heterozygosity, supports the possibility of partial outcrossing, which may be facilitated by insect pollination. Population structure analyses revealed seven distinct genetic clusters which were not correlated with geography, suggesting historical seed exchange and germplasm movement across regions. Tanzanian farmer collections harbor genetic variation that is not represented in local seedbanks, underscoring the significance of on-farm conservation and the need for future collection efforts. These findings pave the way for further genome research in marker-assisted breeding, which will contribute to future food security and sustainable livelihoods.