THE ARABIDOPSIS MALE-STERILITY-2 PROTEIN SHARES SIMILARITY WITH REDUCTASES IN ELONGATION CONDENSATION COMPLEXES/

The Arabidopsis thaliana MALE STERILITY 2 (MS2) gene product is involv ed in male gametogenesis. The first abnormalities in pollen developmen t of ms2 mutants are seen at the stage in microsporogenesis when micro spores are released from tetrads. Expression of the MS2 gene is observ ed in tapetum of wild-type flowers at, and shortly after, the release of microspores from tetrads. The MS2 promoter controls GUS expression at a comparable stage in the tapetum of transgenic tobacco containing an MS2 promoter-GUS fusion. The occasional pollen grains produced by m utant ms2 plants have very thin pollen walls. They are also sensitive to acetolysis treatment, which is a test for the presence of an exine layer. The MS2 gene product shows sequence similarity to a jojoba prot ein that converts wax fatty acids to fatty alcohols. A possible functi on of the MS2 protein as a fatty acyl reductase in the formation of po llen wall substances is discussed.