INVITRO PLANT-REGENERATION OF SPINACH FROM MATURE SEED-DERIVED CALLUS

A system for the regeneration of spinach (Spinacia oleracea L.) from mature dry seed explants has been established. The response of two commercial spinach cultivars, 'Grandstand' and 'Baker,' was examined. Callus proliferation was most prominent on MS medium supplemented with 9.3-mu-M of 6-furfurylaminopurine (kinetin) and 3.39-mu-M 2,4-dichlorophenoxyacetic acid (2,4-D). Adventitious shoot formation was observed within 8 wk after callus was transferred onto regeneration medium. Shoot regeneration was best from callus induced on 9.3-mu-M kinetin and 4.56-mu-M 2,4-D. The regeneration medium contained 9.3-mu-M kinetin, 0.045-mu-M 2,4-D, and 2.89-mu-M gibberellic acid (GA3). Shoots were rooted on hormone-free medium, and plants grown in a greenhouse showed normal phenotype. This system is beneficial in rapid propagation of spinach plants, particularly when only a limited number of seeds are available.