Relationship between Pollen and Embryo Sac Development in Wheat, Triticum aestivum L.

Abstract

In most florets, meiosis of pollen mother cells and of the embryo sac mother cell within the same floret begin concurrently, but after leptotene, the latter proceeds more slowly than the former. When the embryo sacs have one, two, four, or eight nuclei, the pollen grains have a single and eccentrically located nucleus As the embryo sac reaches the seven-celled stage, the pollen grains generally advance to the stage of (1) a single, eccentric nucleus; (2) the first mitotic division; or (3) two nuclei. By the time the embryo sac has proliferated antipodal cells, the pollen grains are two-nucleate. When the embryo sac becomes mature, the pollen grains are in the three-nucleate stage. The development of pollen grains from microspores takes much longer than that of the embryo sacs from the megaspores. The male and female gametes are regulated to mature at the same time so as to facilitate self-pollination