Ultrastructure Observation of M. halliana Pollen During Development

Abstract

In order to explore possible reasons for pollen abortion in monopetalous Malus halliana, we conducted anatomical observations during pollen development. Conventional electron microscopy was used to observe the cytological characteristics of pollen and microspore development in monopetalous M. halliana. We discovered that pollen abortion mainly occurred at the later stage of meiosis in the microsporocytes and during subsequent stages. The main cause of pollen abortion was attributed to the tapetal cells in the anther walls not being able to normally degrade during the tetrad stage, which resulted in the tetrads being unable to normally separate. In addition, the middle-layer cells and tapetal cells could not normally degrade or disintegrate at the tetrad stage and during subsequent stages. This resulted in nutrient deficiency during the pollen maturation stage, ultimately resulting in pollen abortion.