GENETIC-CONTROL OF MALE-FERTILITY IN ARABIDOPSIS-THALIANA - STRUCTURAL-ANALYSIS OF PREMEIOTIC DEVELOPMENTAL MUTANTS

We have taken a mutational approach to identify genes important for ma le fertility in Arabidopsis thaliana and have isolated a number of nuc lear male/sterile mutants in which vegetative growth and female fertil ity are not altered. Here we describe detailed developmental analyses of four mutants, each of which defines a complementation group and has a distinct developmental end point. All four mutants represent premei otic developmental lesions. In ms3, tapetum and middle layer hypertrop hy result in the degeneration of microsporocytes. In ms4, microspore d yads persist for most of anther development as a result of impaired me iotic division. In ms5, degeneration occurs in all anther cells at an early stage of development. In ms15, both the tapetum and microsporocy tes degenerate early in anther development. Each of these mutants had shorter filaments and a greater number of inflorescences than congenic male-fertile plants. The differences in the developmental phenotypes of these mutants, together with the non-allelic nature of the mutation s indicate that four different genes important for pollen development, have been identified.