Pollen Germination, Pollen-Pistil Interaction and Crossability Studies in Interspecific and Induced Colchiploid Population of Abelmoschus Species

Okra is one of the important vegetable crops suffering from yield losses due to various biotic stresses. Crop wild relatives are reservoir of genetic resistance to biotic stresses but their utilization in crop breeding is restricted by various pre- and post-zygotic crossing barriers. In our study, multiple stress tolerant lines 'IC90476-1' of Abelmoschus manihot var. tetraphyllus and (IC141055) of Abelmoschus moschatus were crossed reciprocally with commercially grown variety Pusa A-4 of A. esculentus. Subsequently, only direct cross (Abelmoschus esculentus as female parent) F(1)s, amphidiploidized (C-1), selfed and backcrossed with A. esculentus variety Pusa A-4 were raised to investigate the crossability barriers. Abelmoschus manihot var. tetraphyllus was found to be bi-directionally crossable with A. esculentus and not hampered by any serious pre- and post-zygotic barriers. But differences in ploidy leads to failing in production of F-1 seeds upon selfing and backcrossing. Therefore, amphidiploidization of F-1 hybrid followed by selfing and backcrossing (amphidiploid as seed parent) is recommended as an effective strategy to transfer desirable traits from A. manihot var. tetraphyllus to A. esculentus. However, A. moschatus x A. esculentus crosses suffered from severe pre-zygotic barriers that resulted in formation of aborted embryo with partially filled seeds. Therefore, use of A. esculentus only as female parent, in crossing with A. moschatus may increase the production of viable F-1 seeds. In conclusion, colchicine (0.1%) induced amphidiploidization was found effective for restoration of fertility. However greater success was obtained in reciprocal backcrossing (A. esculentus x F-1/C-1) compared to amphidiploidization followed by selfing of C-1 was recommended for gene introgression from A. moschatus.