Contrasting genetic variation amongst lentil landraces from different geographical origins

Lentil landraces from South Asia exhibit a low diversity and discordance with landraces from other countries according to a combination of qualitative and quantitative agromorphological characters. They exhibit specific phenological adaptation to the South Asian environment which precludes the direct use of alien germplasm in breeding programs in South Asia. An understanding of the genetic relationships and diversity of South Asian lentil landraces, in relation to landraces from other countries, is important in attempting to widen the genetic base of germplasm in the region. The objectives of this study were to investigate the genetic relationships between lentil landraces from 3 South Asian countries (India, Nepal and Pakistan) and those from 13 other countries and to determine their relative genetic diversities, using both isozyme electrophoresis and random amplified polymorphic DNA (RAPD) analysis. Polymorphisms were observed for 7 isozyme loci (16 alleles) and 22 RAPD loci. According to Nei's genetic distance, germplasm from Afghanistan clustered with that from the South Asian countries. The germplasm from these countries was striking different to that from the other countries studied. Based on genetic distance estimates from RAPD analysis, the countries with the lowest diversity were Pakistan, Afghanistan and Nepal. These data support evidence at the morphological level of a genetic bottleneck in lentil landraces from South Asia. Genetic relationships between countries outside the South Asian group are discussed. Classification into macrosperma and microsperma types did not reflect overall country relationships.