FLOWER DEVELOPMENT IN NORMAL TOMATO AND A GIBBERELLIN‐DEFICIENT (ga‐2) MUTANT

Abstract

Flower buds of a tomato ( Lycopersicon esculentum Mill.) gibberellin‐deficient mutant ( ga‐2/ga‐2 ) were initiated, but did not develop to maturity and eventually aborted. If GA, was applied to a developing inflorescence or stem tip, completion of flower bud development and fruit set occurred. In development of the ga‐2 flowers, the corolla and stamens did not elongate and the style was misshapen or extended past the tip of the anthers. Light microscope observations indicated that meiosis of both microsporocytes and megasporocytes did not occur. Cells of the sporogenous layer were initiated, but growth was arrested and they eventually degenerated. The ovary was normal in appearance. However, the megasporocytes degenerated, giving rise to a cavity in the ovule. Thus, although GA is not required for flower initiation in tomato, it is essential for meiosis of the microsporocytes and megasporocytes and elongation of the corolla and stamens.