Establishment and Molecular Validation of a Lima Bean (Phaseolus lunatus) Core Collection in Brazil

Abstract

A gap exists between the growth of active germplasm collections and their effective use because of the size of these collections and the limitations of financial resources, skilled labor, and information on the traits of each accession conserved in germplasm banks. To overcome this, the development of core collections (CCs) is of significant importance. In this study, we established the CCs of lima bean (Phaseolus lunatus) accessions from the Germplasm Bank of Phaseolus at the Universidade Federal do Piauí based on two selection strategies and performed validation based on nuclear microsatellite (ncSSR) data. Two CCs were established from 395 accessions and characterized by 11 phenotypic traits of the seed. These CCs were defined using proportional and logarithmic sampling strategies, each consisting of 79 accessions. A set of 13 ncSSRs was used to validate and estimate the genetic diversity. The estimates of parameters (means, variances, and amplitudes of variation), kurtosis, skewness, and average variability retention index indicated no differences between the two CCs when compared with the entire collection (EC). However, the comparison between the accessions that did not coincide with the two CCs through ncSSRs showed differences. The logarithmic CC showed higher expected heterozygosity, mean number of alleles, and number of private alleles (0.521, 4.308, and 30, respectively) than those of the proportional CC strategy (0.352, 2.154, and 2, respectively), indicating greater genetic diversity. Thus, the logarithmic CC proved to be more suitable for conservation purposes and should be further examined in the establishment of thematic collections of lima beans.