Genetic diversity of two Indian common bean germplasm collections based on morphological and microsatellite markers

Abstract

India is the second most populous nation in the world after China, and its plant genetic resources are an important basis for crop improvement to meet human population needs. An important legume in the diet of the Indian population is common bean (Phaseolus vulgarisL.). Common beans are one of the many important legumes grown in India, but unlike others, its centre of origin is not in Asia but in the Americas. The objective of this study was to evaluate two collections of Indian common beans: one for an internationally available collection of Food and Agriculture Organization (FAO)-protected accessions and one from the north-western Himalayan region. In total, 149 Indian landraces were evaluated with a total of 24 microsatellites across the two collections, and these represented all common bean-growing states of India. A population structure analysis was used to find groups in each collection, and this was compared across the collections. The genetic analysis of the two sets of Indian accessions with neighbour-joining trees and principal component analysis categorized the landraces into Andean and Mesoamerican gene pool groups. The Andean genotypes dominated the north-western Himalayan collection while the FAO-protected accessions were predominantly Mesoamerican. The Indian subcontinent can be considered as a region of high bean diversity; however, very little introgression was observed between the gene pools in both the germplasm sets. Gene pool identity was further substantiated by the comparison of seed traits, particularly seed size. The role of the landraces in plant breeding programmes is discussed.