Assessment of genetic variability and genetic manipulations in lentils (L. c. ssp. culinaris Medikus)

Abstract

A series of experiments were conducted to assess the genetic variability and genetic relationships among Lens species at molecular (RAPD-PCR), biochemical (SDS-PAGE) and morphological levels. This information was further utilised to create new forms of genetic variation by establishing interspecific hybridization in the genus Lens by sexual means. Newly developed interspecific hybrids were then tested at molecular, biochemical and morphological levels for their true hybridity and their apparent genetic relationships to their respective parents using RAPD, SDS-PAGE and morphological criteria. To overcome the potential problems of sterility and failure of hybrid flowering of interspecific hybrids, an in vitro protocol was developed and then used to increase the F1 hybrid population size. The value of interspecific hybrids was demonstrated by testing them along with their parents against ascochyta blight of lentils caused by Ascochyta fabae f. sp. lentis.

The genetic basis of cultivated lentil (Lens culinaris ssp. culinaris) was found to be narrower than that of other Lens species. Lens culinaris ssp. orientalis appeared to be the wild progenitor of cultivated lentils while a gene flow from Lens odemensis and Lens ervoides during lentil crop evolution was quite possible. The use of random morphological characters was not reliable for taxonomic studies in the genus Lens. Nuclear and biochemical markers appeared to be the most consistent and reliable indications for genetic relationships. Lens nigricans accession W6 3222 (unknown) and Lens culinaris ssp. orientalis W6 3244 (Turkey) were reclassified as Lens odemensis accessions based on RAPD information.

Genetic inheritance of resistance to ascochyta blight was found to be controlled by two complementary dominant gene pairs in cultivated and wild species of the genus Lens where both genes must be present in the dominant form, whether homozygous or heterozygous for complete resistance. In all genotypes, resistance was also moderated by other inter-genic interactions.

Utilization of the Lens model system developed here for taxonomic and crossability studies of other genera of tribe Vicieae is suggested.