Morphogenesis of the stamenless-2 mutant in tomato. II. Modifications of sex organs in the mutant and normal flowers by plant hormones

Abstract

Application of gibberellic acid (GA 3 ) to young plants of a single gene recessive stamenless-2 (sl 2 /sl 2 ) mutant of tomato produced 'phenocopies' of the normal plants. Unlike the untreated sl 2 /sl 2 mutant, flowers of GA 3 -treated plants bore no external ovules, possessed more yellow-pubescent stamens and fewer carpelloid stamens per flower, and produced laterally fused stamens. Stamen length at maturity was similar to normal flowers. In addition, viable pollen resembling the normal was produced in GA 3 -treated sl 2 /sl 2 flowers. It was also found that GA 3 was more effective than GA 4+7 in inducing stamen development. Normal plants treated with GA 3 produced multicarpellary and multilocular ovaries. Indoleacetic acid (IAA) induced the carpellization of stamens in sl 2 /sl 2 flowers but had no apparent effect on the flowers of normal plants. It is proposed that added gibberellins promote maleness in systems where there is an inhibition or abnormality of stamen development, whereas they stimulate femaleness (possibly through an increase in auxin content) in systems with normal stamen development.