Sack F D, Leopold A C, Hoekstra F A
Department of Botany, Ohio State University, Columbus 43210-1293.
Am J Bot. 1988;75(4):570-8.
The ultrastructure of Typha latifolia pollen was examined as a function of pollen moisture content and incubation temperature, in order to identify possible lesions induced by imbibitional chilling. A syndrome of structural traits was found which characterizes damaged grains. Compared to viable grains, the protoplast of damaged pollen has a higher proportion of its volume occupied by vesicles, and less volume occupied by cytoplasm. Damaged grains also tend to have dilated cisternae of endoplasmic reticulum, larger starch grains and lipid bodies, poorly preserved mitochondria and membranes, and, sometimes, numerous electron-dense globules associated with membranes. The percentage of grains exhibiting this damage syndrome correlates closely with the number of ungerminated grains in most samples, regardless of moisture content or incubation temperature. Injury due to rapid imbibition from the dry state or to imbibitional chilling appear to be similar structurally, regardless of whether the stresses are imposed singly or together. The injury is not confined to one cell component (e.g., mitochondria), but may involve a generalized disruption of membranes. These results suggest that similar stress responses are elicited by imbibition from the dry state and by imbibitional chilling.
为了确定吸胀冷害可能引发的损伤，研究了宽叶香蒲花粉的超微结构与花粉含水量及培养温度之间的关系。发现了一组表征受损花粉粒的结构特征综合征。与有活力的花粉粒相比，受损花粉的原生质体中，小泡所占体积比例更高，细胞质所占体积更小。受损花粉粒还往往具有内质网池扩张、淀粉粒和脂质体更大、线粒体和膜保存不佳，有时还有许多与膜相关的电子致密小球。无论含水量或培养温度如何，在大多数样本中，出现这种损伤综合征的花粉粒百分比与未萌发花粉粒的数量密切相关。无论是单独施加还是同时施加胁迫，从干燥状态快速吸水或吸胀冷害造成的损伤在结构上似乎都相似。这种损伤并不局限于某一种细胞成分（如线粒体），而是可能涉及膜的普遍破坏。这些结果表明，从干燥状态吸水和吸胀冷害引发了相似的应激反应。
