Effect of harmones on callus induction in Maize (Zea mays L.)

Callus induction from explants is a critical process in regeneration, micropropagation and transformation of maize (Zea mays L.) plants. Formation of callus from plant tissues on culture is affected by several factors. This study revealed to establish the effect of genotype, source of explants and auxin concentration on callus induction from five genotypes UMI 757 (G1), UMI 615 (G2), UMI 112 (G3), UMI 285 (G4) and CO 1 (G5) and one hybrid CO H (M) 5 (G6). Callus induction of the six maize varieties was investigated using immature embryos (E1), leaf bits (E2), root tips (E3), hypocotyls (E4) and seeds (E5) as explants with different concentrations of hormones. In this study, immature embryo was taken from 10 to 12 days after pollination (DAP) to get maximum response. The highest percentage of callus induction was observed (99.10) in immature embryo culture and seed culture gave the highest percentage of rhizogenic callus formation when compare to immature embryo. Among the genotypes tested, CO H (M) 5 recorded the highest callus induction percentage on (2D2K2) medium composition.

Plant regeneration from immature embryo culture of Trifolium michelianum savi. - histological observations on adventitious shoot induction

Whole plant regeneration via organogenesis in immature embryo culture of <em>Trifolium michelianum</em> Savi. was obtained. The shoots were induced directly from the hypocotyl or indirectly through callus on EC6 medium supplemented with 0.5 and 5 mg/l BAP, respectively. Sporadically the callus formation was preceded by shoot regeneration. Both shoots obtained directly and via callus regenerated into plants when subcultured on half-strength Murashige and Skoog (MS) medium, free of growth regulators. Histological observations revealed that the shoots were induced directly from the ring of meristematic tissue which was formed at the periphery of the hypocotyl or indirectly from the superficial cells of the callus. Irrespective of the mode of regeneration the shoots were of multicellular origin.