SHOOT REGENERATION FROM CULTURED ROOT EXPLANTS OF SPINACH (SPINACIA-OLERACEA L) - A SYSTEM FOR AGROBACTERIUM TRANSFORMATION

A reliable plant regeneration system is described for the production o f adventitious shoots from root explants of spinach. Explants from roo ts of axenic shoots and roots induced on cultured hypocotyl explants w ere used for adventitious shoot induction. Explants from apical, middl e and basal root regions were incubated on Nitsch and Nitsch medium su pplemented with alpha-naphthaleneacetic acid, gibberellic acid and kin etin. Optimum shoot regeneration was from explants of apical and middl e root regions on medium with 20 mu M alpha-naphthaleneacetic acid and 5.0 mu M gibberellic acid. Shoots originated directly from root tissu es without an intervening callus phase. Adventitious shoots were roote d and were grown to maturity in the glasshouse. This plant regeneratio n procedure has been exploited in preliminary studies of Agrobacterium -mediated transformation.