キウイフルーツの雌株品種における花粉退化

Abstract

Microsporogenesis was studied on two pistillate kiwifruit cultivars, 'Bruno' and 'Abbott' to clarify the process of pollen degeneration. The process was compared to that of the staminate cultivar, 'Matua'. In the early stages, quite similar morphogenesis was observed in tapetal behavior, meiosis of pollen mother cells and pollen tetrad formation between the two pistillate and the staminate cultivars. In the pistillate cultivars the pollen starts to degenerate after the liberation of micospores seemingly because the tapetal cells fail to nourish it. Thus, the tapetum remains nearly intact until anthesis. In the staminate cultivar the tapetal cells begin to degenerate soon after the liberation of microspores from the tetrad stage; the degeneration is almost complete by anthesis. Hence, we conclude that pollen degeneration in the pistillate kiwifruit cultivars begins after the pollen tetrad stage because of abnormal tapetal behavior.