Tissue Culture Approaches to Pigeonpea Improvement

Pigeonpea anthers were cultured on different media to develop haploids. MS medium supplemented with 2 mg/L of 2,4 dichlorophenoxy acetic acid (2,4-D) supported the development of callus from Cajanus cajan anthers, while potato starch extract medium promoted the best response from anthers of Atylosia gradifolia and A. volubilis. Such calli failed to differentiate on subculturing on media supplemented with combinations of hormones. Screening for chromosome elimination following intergeneric hybridizations was not successful in haploid formation. Culture conditions for plantlet regeneration from immature embryos of Cajanus have been standardized for further embryo rescue following distant hybridizations. An age-dependent embryo response was evident. Embryos older than 11 days developed into plants on MS or B5 media supplemented with 2,4-D (1 mg/L). The B5 medium was superior to MS for regeneration. Plantlets were also regenerated from explants of cotyledons from mature seeds, leaves and epicotyls of seedlings of Cajanus cultivars and Atylosia species in different media supplemented with hormones [2,4-D, napthalene acetic acid (NAA), benzyl adenine (BA), kinetin and gibberelic acid (GA3)]. Whole cotyledons or their proximal segments were found to be suitable for regeneration