Bonner Lynda J, Dickinson H G
Department of Botany, School of Plant Sciences, University of Reading, Whiteknights, Reading, RG6 2AS.
New Phytol. 1990 Jun;115(2):367-375. doi: 10.1111/j.1469-8137.1990.tb00463.x.
Water tracers have been used to demonstrate the continued functioning of the anther filament during dehiscence in Lycopersicon esculentum Mill. Since Lycopersicon possesses neither nectar nor nectaries dehiscence cannot be related to sugar secretion, as has been demonstrated for other plants. The anthers seem structurally adapted for water conservation and the only transpirational loss of the flower appears to be through the petals. Transpiration from the anthers themselves thus appears not to be involved in regulating dehiscence. Anther opening is preceded by dehydration of the locule and circumstantial evidence indicates it to be an active process, with water being exported through the filaments to the petals along an osmotic gradient generated by starch/sugar interconversion. Measurement of water potential differentials between the petals and anthers points to the mechanism driving this export of water from the anthers. Interestingly, turgor pressure is maintained in the majority of the anther tissues until senescence, remaining remarkably constant against a background of dramatic changes in osmotic potential. These data, combined with the observation that the hydration level of the anthers falls only to 70% at senescence, indicates that dehiscence cannot primarily be a desiccatory process. Some domains within the anther do desiccate, but these are strictly localized. Thus, while hydration levels of living tissues remain independent of the environment, those observed to undergo protoplast degeneration and wall collapse exhibit environmentally-linked hygroscopic absorption. Dehiscence thus emerges as an orchestrated programme of structural and physiological events leading to the desiccation of specific domains of the anthers. These findings are discussed in terms of current models for anther dehiscence in flowering plants.
水示踪剂已被用于证明番茄（Lycopersicon esculentum Mill）花药开裂过程中花丝的持续功能。由于番茄既没有花蜜也没有蜜腺，与其他植物不同，其花药开裂与糖分分泌无关。花药在结构上似乎适应于水分保持，花朵唯一的蒸腾失水似乎是通过花瓣进行的。因此，花药本身的蒸腾作用似乎与调节花药开裂无关。花药开裂之前，药室会脱水，间接证据表明这是一个活跃的过程，水分沿着由淀粉/糖相互转化产生的渗透梯度通过花丝输送到花瓣。花瓣和花药之间水势差的测量指出了驱动花药水分输出的机制。有趣的是，在大多数花药组织中，直到衰老时都保持着膨压，在渗透势发生巨大变化的背景下，膨压保持显著恒定。这些数据，再加上花药在衰老时水合水平仅降至70%的观察结果，表明花药开裂主要不是一个干燥过程。花药内的一些区域确实会干燥，但这些区域是严格局部化的。因此，虽然活组织的水合水平与环境无关，但那些观察到发生原生质体退化和细胞壁塌陷的组织表现出与环境相关的吸湿作用。花药开裂因此成为一个精心编排的结构和生理事件程序，导致花药特定区域的干燥。本文根据开花植物花药开裂的当前模型对这些发现进行了讨论。
