Abstract
Anthers of three male sterile mutants of tomato plants and their original cv. First were subjected to several factors which affected callus induction and shoot regeneration. Callus induction capacity was significantly improved by the presence of ms genes which disrupt microsporogenesis at meiosis in the anthers of Fms-2 line. Fms-1 and Fms-3, which block microsporogenesis at microspore and tetrad formation respectively, were inferior to Fms-2 in callus induction. Experiments carried out with the Fms-2 line demonstrated that the developmental stage of the explant was a crucial factor in callus formation and that optimum stage was between pre-meiosis and metaphase I, which corresponds to the stage just after the blockage of microsporogenesis. Callus was efficiently induced from anthers, pretreated at 4°C for 3 days, on MS medium, supplemented with 5.0 mg·liter-1 IAA and 2.5 mg·liter-1 zeatin, under a 16-hr photoperiod. The highest frequency of shoot differentiation was achieved on MS medium, supplemented with 0.2 mg·liter-1 kinetin.
