Interspecific Hybridization in genus Helianthus through Embryo Rescue

In a direct approach to rescue interspecific hybrids, immature embryos of cv. Morden were cultured at different developmental stages i.e. 1-4 weeks after fertilization on four percentage. Maximum germination percentage was observed from 4-weeks-old embryos. The best results were obtained on B5 medium fortified with 90.0 g.l-1 sucrose +0.5 mg.l-1 NAA + 100 mg.l-1 myo-inositol + 600 mg.l-1 L-alanine + 120 mg.l-1 L-serine + 40 mg.l-1 tryptophan + 6 mg.l-1 cystine which supported maximum germination from embryos of all ages. For immature embryo culture, five different fortifications of basal B5 and MS media were tested supplementing different growth regulators in varying combinations and concentrations. The analysis of variance indicated presence of considerable amount of variability among genotypes, culture media and genotypes x culture medium interactions for initiation of callus cultures, formation of morphogenic calli and plantlet regeneration. Higher in vitro responses were exhibited by genotypes Guj 41 followed by Guj 15 and TNAU 171. Better results were obtained with culture medium B5 supplemented with 1.5 mg.l-1 BA + 0.5 mg.l-1 NAA + 30 g.l-1 sucrose + 8 g.l-1 agar as compared to rest of the four culture medium tested.