Seed germination in a tomato male-sterile mutant is resistant to osmotic, salt and low-temperature stresses

Seed germination in a male-sterile 7B-1 mutant in tomato is reletively more resistant to the inhibitory effects of a high osmoticum induced by mannito l and polyethylene glycol, to various salts, including NaCl, Na2SO4, KCl an d K2SO4, and to low-temperature stress, compared to the wild-type (WT) seed s. The inhibitory effects of various stresses could be partly or completely overcome by fluridone (FLU), an inhibitor of abscisic acid (ABA) biosynthe sis. However, lower concentration of fluridone was required for the 7B-1 mu tant than for WT seeds, and the mutant seeds were more sensitive to the inh ibitory effects of exogenous ABA. The data suggest that 7B-1 seed has a pre -existing level of elevated ABA which imparts resistance to the various str esses. The ability to regulate male sterility in the 7B-1 mutant by photope riod, as previously reported by Sawhney (1997), and its resistance to abiot ic stresses, as reported here, makes this a useful system for tomato breedi ng and in hybrid programs.