Switch (swi1), an Arabidopsis thaliana mutant affected in the female meiotic switch

In this paper, we describe a novel plant mutant affected exclusively in the female mitosis-meiosis switch. The major effect of the swil mutation in Ar abidopsis thaliana L. is to delay megasporogenesis events by inserting addi tional mitotic divisions of the megasporocyte. As a result of this delay, m egagametogenesis is also affected. The absence of cellular polarity in the megasporocytes was also observed. Ovule ontogenesis is not affected by the mutation. The swil mutant is particularly interesting for studying sporophy t-gametophyte interactions. The swil mutation, obtained from a T-DNA taggin g experiment, is monogenic recessive and mapped on chromosome five, at 16 c M from the yellow inflorescence marker.