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Calcium distribution during pollen development in Bauhinia blakeana

Zheng, RenHua, De Su, Shun, Xiao, Hui, Tian, HuiQiao
Trees 2018 v.32 no.2 pp. 465-472
Bauhinia blakeana, calcium, callose, meiosis, mitochondria, plasma membrane, pollen, potassium, vacuoles
KEY MESSAGE: In this manuscript, we first found calcium induces vacuoles formation from mitochondria during microspore development in Bauhinia blakeana, which is not reported yet. Potassium antimonite was used to locate calcium in anther cells of Bauhinia blakeana to determine the role of Ca²⁺ in pollen development. Some calcium-induced precipitates were observed in early sporogenous cells after which numerous small vacuoles containing calcium precipitates appeared following transformation into microspore mother cells. The small vacuoles were then secreted from the plasma membrane to the callose wall. After meiosis, the number of precipitates in the early microspore cytoplasm increased, accumulating mainly in the mitochondria, the inner membrane (cisterns) of which was then destroyed to create small vacuoles. These small vacuoles then fused to form a large vacuole, which subsequently polarized the cell. After microspore division and decomposition of these large vacuoles, numerous calcium precipitates accumulated in the small vacuoles, which were then secreted out of the pollen. These findings suggest a role of calcium in the regulation of vacuole formation and decomposition during pollen development.