COMPARISON OF DEVELOPMENTAL STAGES OF INFLORESCENCE FOR HIGH-FREQUENCY PLANT-REGENERATION IN TRITICUM-AESTIVUM L AND TRITICUM-DURUM DESF

Whole immature inflorescences at 4 different developmental stages (0.5 , 1.0, 1.5, 2.0 cm in size) of different genotypes of Triticum aestivu m and T. durum were cultured to see the morphogenetic responses on Mur ashige and Skoog's (MS) medium supplemented with 2,4-dichlorophenoxyac etic acid (2,4-D) (2.5 mg/l). Very young inflorescences 0.5 and 1.0cm long formed embryogenic callus from their entire surface while. 1.5 an d 2.0 cm long inflorescences formed embryogenic callus from the basal spikelets and rachis only. This embryogenic callus was maintained by r egular subcultures on MS medium with 2,4-D (2.5 mg/l) for more than a year. Plantlets were regenerated by transferring the embryogenic callu s on hormone-free MS medium. Inflorescences (0.5 and 1.0 cm long) resp onded best in forming callus as well as plantlets at a very high frequ ency. Variation in response was observed amongst the genotypes but the qualitative response of formation of embryogenic callus and later reg eneration of plantlets was observed from all the genotypes. Immature y oung inflorescence explants could provide a suitable material for part icle gun mediated genetic transformation in wheat.