Calcium distribution in fertile and sterile anthers of thermosensitive male-sterile wheat

Calcium distribution in fertile and sterile anthers of a thermosensitive male-sterile wheat genotype was investigated using an antimonate precipitation method. During fertile anther development, before meiosis of the microspore mother cells, calcium precipitates were apparent in tapetal cells of the anther wall. After meiosis, precipitates were detected in the early microspores and accumulated in the large vacuole of late microspores. After microspore division, following decomposition of the large vacuole, precipitates decreased in the bicellular pollen. The earliest abnormality in calcium precipitate distribution detected during sterile pollen development was the greater accumulation of precipitates in the cytoplasm and nucleus of late microspores. The sterile microspore can divide to form bicellular pollen, but the large vacuole of sterile bicellular pollen did not decompose and greater abundance of precipitates was retained in the large vacuole. Abnormal distribution of calcium precipitates in sterile pollen precedes structural changes, suggesting that abnormal calcium metabolism is associated with pollen abortion.