Establishment of a Simple Plant Regeneration System Using Callus from Apomictic and Sexual Seeds of Guinea Grass (Panicum maximum)

Abstract

Aims: For analysis of apomixis genes, as the first step, an efficient and simple plant regeneration system has been established using callus from apomictic and sexual seeds of guinea grass (Panicum maximum). Study Design: The best basic medium for callus formation from matured seeds of guinea grass was selected, and then, the best combinations of growth regulators on different media were selected for plant regeneration by indirect organogenesis. Methodology: Guinea grass accessions of sexual and apomict of seeds were used for culture. Seeds sterilized were cultured in Murashige and Skoog [10] medium (MS) and in that proposed by Chu et al. [12] (N6D) for callus formation. The best medium and, the effects of L-proline and growth regulators’ type and concentrations on callus formation and plant regeneration in 3 accessions were examined, respectively. After the plantlets rooting in MS hormone-free medium, the complete plants were planted in pots for hardening. Results: N6D medium has given better rates for callus formation, that is, 97.1% in sexual N68/96-8-o-5, and 91.7% and 84.6% in apomict N68/96-8-o-11 and ‘Natsukaze’, respectively. MS medium with 0.2 mg/l of Kinetin has given the best rate or plant regeneration among the used 4 kinds of the media. For each material, the best results were obtained on MS with 0.2 mg/l of Kinetin for N68/96-8-o-5, and MS with 2.0 mg/l of L-proline and 0.2 mg/l of Kinetin for ‘Natsukaze’. After hardening of the regenerated plants in soil, 100% of surviving rates were obtained, and showed normal growth comparing with the plants-derived from seeds. Conclusion: We have established, as the first case, an efficient and simple plant regeneration system by using callus from apomictic and sexual seeds of guinea grass for analysis of apomixis genes, consisting of analysis of the best media, L-proline usages and phytohormone combinations for callus formation, plant regeneration and hardening in different stages, respectively.