Mamun E A, Alfred S, Cantrill L C, Overall R L, Sutton B G
Cooperative Research Centre for Sustainable Rice Production, The University of Sydney, NSW 2006, Australia.
Cell Biol Int. 2006 Jul;30(7):583-91. doi: 10.1016/j.cellbi.2006.03.004. Epub 2006 Mar 22.
Chilling during male gametophyte development in rice inhibits development of microspores, causing male sterility. Changes in cellular ultrastructure that have been exposed to mild chilling include microspores with poor pollen wall formation, abnormal vacuolation and hypertrophy of the tapetum and unusual starch accumulation in the plastids of the endothecium in post-meiotic anthers. Anthers observed during tetrad release also have callose (1,3-beta-glucan) wall abnormalities as shown by immunocytochemical labelling. Expression of rice anther specific monosaccharide transporter (OsMST8) is greatly affected by chilling treatment. Perturbed carbohydrate metabolism, which is particularly triggered by repressed genes OsINV4 and OsMST8 during chilling, causes unusual starch storage in the endothecium and this also contributes to other symptoms such as vacuolation and poor microspore wall formation. Premature callose breakdown apparently restricts the basic framework of the future pollen wall. Vacuolation and hypertrophy are also symptoms of osmotic imbalance triggered by the reabsorption of callose breakdown products due to absence of OsMST8 activity.
水稻雄配子体发育过程中遭遇低温会抑制小孢子发育，导致雄性不育。暴露于轻度低温下的细胞超微结构变化包括花粉壁形成不良的小孢子、异常液泡化以及绒毡层肥大，减数分裂后花药的药室内壁质体中出现异常淀粉积累。通过免疫细胞化学标记显示，四分体释放期间观察到的花药也有胼胝质（1,3-β-葡聚糖）壁异常。水稻花药特异性单糖转运蛋白（OsMST8）的表达受低温处理的影响很大。碳水化合物代谢紊乱，尤其是在低温期间由受抑制的基因OsINV4和OsMST8引发，导致药室内壁异常淀粉储存，这也促成了其他症状，如液泡化和小孢子壁形成不良。过早的胼胝质分解显然限制了未来花粉壁的基本框架。由于缺乏OsMST8活性，胼胝质分解产物的重吸收引发渗透失衡，液泡化和肥大也是这种失衡的症状。
