A MULTI-NUCLEATE MALE-STERILE MUTANT OF MAIZE WITH GAMETOPHYTIC EXPRESSION

In order to dissect the complex genetic system that controls pollen de velopment, we have undertaken a program of transposon insertion mutage nesis, with the purpose of producing mutations in gametophytically act ing genes that are important for this process, The present work report s the developmental cytology of one of thr mutants isolated, gaMS-2 (g ametophytic male sterile-2). A peculiar feature of tile mutant grains was lack of differentiation between the vegetative and the generative nuclei, leading to alteration in number, conformation and placement of nuclei. At anthesis. the grains carrying the mutant allele are about 40% of the normal grain size, contain a very reduced amount of starch and exhibit various nuclear abnormalities.