Abscisic acid in a male sterile tomato mutant and its regulation by low temperature

Abstract

into regulatory factors in stamen and pollen development, but also help in the development of male sterile systems The role of abscisic acid in male sterility in the for use in breeding programmes. stamenless-2 (sl-2) mutant of tomato (Lycopersicon Earlier work in this laboratory on genic (GMS) and esculentum) was investigated. Vegetative and floral cytoplasmic (CMS ) male sterile lines in tomato parts (except pistil) of sl-2 contain greater amount of (Lycopersicon esculentum) and rapeseed (Brassica napus), abscisic acid (ABA) than the normal wild-type. The suggests that male sterility is, in part, a manifestation of maximum difference in ABA content between sl-2 and hormonal imbalance in flowers, particularly in stamens normal tissues was in stamens, and the increase in (Singh and Sawhney 1992a; Singh et al., 1992; Shukla ABA level in sl-2 stamens coincided with first signs and Sawhney, 1992, 1994). The expression of male sterility of abnormalities in the anthers. Low temperatures is also known to be regulated by environmental factors, restore male fertility in sl-2 and there was a concomit- e.g. temperature, photoperiod and moisture ( Kaul, 1988; ant drop in ABA level in sl-2 leaves and stamens. These Greyson, 1994; Sawhney, 1997), and it has been suggested observations, along with our earlier reports, suggest that the eVects of these external agents are mediated that male sterility in sl-2 is a manifestation of hormonal through hormonal changes (Saini and Aspinall, 1982; imbalance involving high ABA, and that low temper- Singh et al., 1992). ature regulation of male sterility is mediated through The single gene, male sterile stamenless-2 (sl-2) mutant reduction in ABA content. in tomato is an excellent system for investigating the environmental‐hormonal interplay in stamen and pollen