更苏被子植物的光合作用

更苏植物是一类在极度干燥条件下组织会迅速脱水后遇水又能很快复苏的植物.极少数被子植物有这种能力,在双子叶植物中尤其罕见,而且脱水时叶绿素含量和叶绿体完整性变化较少,称为叶绿素保持型(HDT).该类植物的复苏机理简单,研究方便,因而得到更广泛注意.更苏被子植物光合作用的最新研究进展说明,光化学活性是研究更苏植物脱水复苏生理状态的灵敏指标.和普通植物一样,在光下,更苏被子植物的光化学活性随着叶片失水而受到抑制,但奇怪的是在失去95%以上的水分后复水仍可迅速复活.在脱水过程中叶黄素循环和抗氧化系统的上调以及光合膜完整性和稳定性的保持,可能对更苏被子植物的耐脱水性起非常重要的作用.磷酸盐对复苏的影响也表现在复水阶段而且与上述两种保护机理关系不大,因此应该加强更苏被子植物复水阶段的研究.

Photosynthesis of Resurrection Angiosperms

Resurrection plants which are able to quickly reactivate after falling into a period of anabiosis caused by dehydration have been very rare among angiosperms, especially among dicotyledons whose chlorophyll content and chloroplast structure little changed in the course of desiccation, therefore has been called homoiochlorophyllous desiccation-tolerant plants (HDTs). Another type of resurrection angiosperms that lost its chlorophyll during desiccation is called poikilochlorophyllous desiccation-tolerant plants (PDTs). HDTs have been received more attention because of simplicity of protection mechanism which is much easy to the study and utilization of the desiccation tolerance of resurrection angiosperms. Recent advances in studies of photosynthesis of resurrection angiosperms indicate that photochemical activities are sensitive indicators for the study of physiological state of resurrection angiosperms during desiccation and rehydration. Photochemical activities of resurrection angiosperms are inhibited with loss of water similar to those of general plants, however, the magic thing is that they could reactivate rapidly during rehydration even losing more than 95% water. Up-regulations in xanthophyll cycle and antioxidative systems as well as preservation in integrity and stability of photosynthetic membranes during desiccation may be very important to desiccation tolerance of resurrection angiosperms. The fact that phosphate treatment in rehydration stage also strongly influences resurrection indicated importance of studies on rehydration stages of resurrection angiosperms.