Regeneration of pineapple plants via somatic embryogenesis and organogenesis

We have developed efficient methods for plant regeneration, via both embryogenesis and organogenesis, of Smooth Cayenne pineapple, Ananas comosus(L.) Merr. Leaf bases and core (stem) sections of in vitro shoots, produced from culture of crown tip meristem, were used as explants for plant regeneration as follows: (1) Leaf base and core section explants cultured on Murashige and Skoog (MS) medium containing 41 muM 4-amino-3,5,6-trichloropicolinic acid (picloram, P) or thidiazuron (T)/P combinations produced embryogenic tissues. Different types of embryogenic tissues (friable emryogenic tissue, embryogenic cell cluster, and chunky embryogenic tissue) have been developed with varying properties in terms of growth rate and state of development. The embryogenic tissues regenerated shoots upon culture on MS medium containing 13 muM 6-benzylaminopurine (BA) and 1 muM alpha-naphthaleneacetic acid (NAA) followed by culture on MS medium containing 4 muM BA. (2) Crown tip meristems cultured on MS medium containing 13 muM BA followed by leaf explants cultured on MS medium with 27 muM NAA and 1 muM BA produced shoots via direct organogenesis. (3) Explants cultured on MS medium containing 5 muM T and 0.5 muM indole-3-butyric acid (IBA) produced nodular globular structures, which produced shoots upon culture on MS medium containing 1 muM BA and 1 muM gibberellic acid. Shoots obtained from all of the above methods were rooted in half-strength MS medium containing 3 muM NAA and 2.5 muM IBA. Plants were transferred to the greenhouse or shipped to Costa Rica for field trials. Somatic embryo-derived plants exhibited 21% spininess, and organogenic-derived plants exhibited 5% spininess in the field trials.