Modern pea (Lathyrus oleraceus) cultivars exhibit significantly lower genetic diversity relative to landraces, garden cultivars and genebank accessions

Pea ( Lathyrus oleraceus Lam.), formerly ( Pisum sativum L.) is an important grain legume, cultivated worldwide for both food and feed purposes. Gene banks safeguard and maintain the genetic resources of the species. The Nordic Genetic Resource Center (NordGen) manages approximately 4,000 pea accessions. In gene banks, the proportion of genotyped accessions is low. This low number limits available information on accessions, increases the risk of duplicates, and reduces the resource efficiency and applicability of gene bank material. Our study included 304 accessions, comprising 18 modern field pea cultivars and 22 garden pea cultivars. All accessions were genotyped using Diversity Arrays Technology sequencing genotyping. This yielded 30,791 single nucleotide polymorphic markers after quality control. Genetic population structure was analyzed and visualized using neighbor-joining trees and Principal Coordinate Analysis plots. The genetic diversity in the population was high. All modern cultivars clustered together in the Principal Coordinate Analysis plots and were resolved as a monophyletic group with high bootstrap support in the neighbor-joining tree. The garden peas were dispersed and intermixed with historic landraces of European origin. Nepalese and Indian landraces, in conjunction with Abyssinian pea accessions, were resolved as a sister group to the rest of the population. Our results demonstrated significant genetic homogeneity in modern cultivars relative to the subset of accessions analyzed. The population structures found in our analyses added to the limited number of publications on genetic diversity, based on large numbers of genetic markers in pea collections. The results supported the often said, but rarely proven hypothesis, that modern cultivars display reduced genetic diversity in agricultural crops.