Factors Affecting Callus Induction from Anther and Ovary of Okra (Abelmoschus esculentus L.)

Background: Okra [Abelmoschus esculentus (L.) Moench.] is a nutrient-rich vegetable crop widely grown in the tropics and sub-tropics mainly for its edible pods. The haploid technique has been used in plant breeding for the improvements of plants and to develop new varieties in relatively a short time. Hence, we have optimized several factors such as plant growth regulators (PGR), sucrose concentration, cold treatment, type of media and culture conditions for callus induction from the anther and ovary of okra (557 F1 hybrid). Methods: The flower buds of different sizes were collected to determine various stages of development and then subjected to cold pre-treatments. The explants were then cultured on various combinations of PGRs i.e., naphthyloxy acetic (NOA), Indole acetic acid (IAA), 2, 4-Dichlorophenoxy acetic acid (2, 4-D), Benzyl amino purine (BAP), isopentenyl adenine 2iP, Kinetin (KIN) and Thidiazuron (TDZ). Result: The optimum developmental stage of microspore for callus initiation was achieved from flower buds of okra and its size was about 11 mm long. Flower buds that emerged one week after the flowering showed significantly higher percentage of callus induction. The optimum stage for ovary and ovule culture were one or two days prior to anthesis and the flower buds stage was 35±1mm. In conclusion, our study investigated the effect of several factors that affects callus induction in okra and optimized cultured conditions for future haploid development for okra.