EARLY SIGNS OF DISRUPTION OF WHEAT ANTHER DEVELOPMENT ASSOCIATED WITHTHE INDUCTION OF MALE-STERILITY BY MEIOTIC-STAGE WATER-DEFICIT

Water deficit during meiosis in microspore mother cells of wheat (Trit icum aestivum L.) induces male sterility, which reduces grain yield. I n plants stressed during meiosis and then re-watered, division of micr ospore mother cells seems to proceed normally, but subsequent pollen d evelopment is arrested. Stress-affected anthers generally lack starch. We employed light microscopy in conjunction with histochemistry to co mpare the developmental anatomy of water-stress-affected and normal an thers. The earliest effects of stress, detectable between meiosis and young microspore stages, were the degeneration of meiocytes, loss of o rientation of the reproductive cells, and abnormal vacuolization of ta petal cells. Other effects observed during subsequent developmental st ages were deposition of starch in the connective tissue where it is no rmally not present, hypertrophy of the middle layer or endothecial cel ls, and deposition of sporopollenin-like substances in the anther locu lus, The resulting pollen grains lacked both starch and intine. These results suggest that abnormal degeneration of the tapetum in water-str essed anthers coupled with a loss of orientation of the reproductive c ells could be part of early events leading to abortion of microspores.