Utilization of Wild Species in Okra (Abelmoschus esculentus) Improvement
摘要
The genus Abelmoschus in India comprises approximately 17 species, with three of them being cultivated and the rest are wild. Additionally, subspecies within A. angulosus, A. moschatus, A. tetraphyllus, and A. tuberculatus have been identified, each with a unique distribution range, limited adaptability, and distinct traits. These entities naturally occur across various eco-geographic regions in India, thanks to diverse microclimates and adaptive niches. The cultivation of okra faces challenges from OYVMV and OELCV, necessitating the search for resistance in closely related wild taxa and their incorporation into cultivated okra. This work aimed to screen and identify sources of tolerance to OYVMV and OELCV while developing hybrids of okra with different donor wild species. Crosses were made between cultivated okra varieties and A. angulosus var. grandiflorus, A. caillei, A. tetraphyllus, A. enbepeegearense, A. pungens var. mizoramensis sp. nov. (Mizoram), A. moschatus subsp. rugosus, and A. moschatus. F1 hybrids were raised, although advancing them to the next generation proved challenging as interspecific hybrids failed to produce viable seeds through selfing and backcrossing. Fertility was restored in the crosses through colchicine treatment and diploidization. Amphidiploids of most hybrid combinations displayed intermediate traits, with prolific fruit bearing. However, the presence of prickly hairs on fruits and a high proportion of tough fibers in amphidiploids hindered their direct utilization. Therefore, backcrossing to okra and selective breeding among segregants for increased seed production and the recovery of cultivated okra fruit characteristics were undertaken. This process generated progenies that successfully crossed with cultivated okra. This report provides details of the procedures used to produce successful crosses and their fertile derivatives within the cultivated okra genetic background. This ensures genetic enhancement of the cultivated gene pool with genes for the target traits of OYVMV and OELCV tolerance, as well as nontarget but valuable traits such as profuse and extended flowering, increased fruit bearing, vigorous plant habits, and sturdiness. It should be noted that the materials generated in this study and deposited with ICAR-NBPGR serve as sources of beneficial genes for okra improvement programs, even though they may not be suitable for direct commercial cultivation due to the presence of a few undesirable characteristics.