Genetic enhancement of okra [ Abelmoschus esculentus (L.) Moench] germplasm through wide hybridization

The introgression of genetic material from one species to another through wide hybridization and repeated back-crossing, plays an important role in genetic modification and enriching the cultivated gene-pool with novel genetic variations. Okra ( [(L.) Moench)] is a popular vegetable crop with high dietary fibre and protein, rich in essential amino acids, lysine and tryptophan. The wild genepool has many desirable traits like ornamental value, short internodal length, more number of productive branches, extended bearing, perennation tendency, reduced fruit length (more consumer preferred trait), high mucilage content (medicinal value), abiotic stress tolerances such as drought, high temperature and biotic stress resistances such as okra Yellow Vein Mosaic Virus (YVMV) and Enation Leaf Curl Virus (ELCV) diseases. The repeated use of elite breeding lines led to narrowing of the genetic base of the okra crop, one of the major factors attributed to breakdown of resistance/ tolerance to biotic stresses. YVMV and ELCV are the two major diseases, causing significant yield loss in okra. Hence, wide hybridization was attempted to transfer tolerance genes from wild species to the cultivated genepool to widen the genetic base. The screening of germplasm of wild species at hotspots led to the identification of tolerant species ( , , , and ), which were further used in a wide-hybridization programme to generate interspecific hybrids with the cultivated okra. Presence of pre- and post-zygotic barriers to interspecific geneflow, differences in ploidy levels and genotype specific variations in chromosome numbers led to varying degrees of sterility in F plants of interspecific crosses. This was overcome by doubling the chromosome number of interspecific hybrids by applying Colchicine at the seedling stage. The 113 cross derivatives generated comprising amphidiploids in the F generation (30), F (14), one each in F and F generations, back cross generation in BC F (03), BC F (25), and BC2F3 (02), crosses between amphidiploids (27), multi-cross combinations (07) and inter-specific cross (between × subsp. ) selfed derivatives at F generation (03) were characterized in the present study. Besides they were advanced through selfing and backcrossing. The amphidiploids were found to possess many desirable genes with a considerable magnitude of linkage drag. Majority of the wide cross derivatives had an intermediate fruit morphology and dominance of wild characters ., hispid fruits, s