دانلود رایگان مقاله انگلیسی تاثیر خشکسالی بر روی حمل و نقل فلوئم - الزویر 2018

Drought impacts on phloem transport have attracted attention only recently, despite the well-established, and empirically verified theories on drought impacts on water transport in plants in general. This is because studying phloem transport is challenging. Phloem tissue is relatively small and delicate, and it has often been assumed not to be impacted by drought, or having insignificant impact on plant function or survival compared to the xylem. New evidence, however, suggests that drought responses of the phloem might hold the key for predicting plant survival time during drought or revival capacity after drought. This review summarizes current theories and empirical evidence on how drought might impact phloem transport, and evaluates these findings in relation to plant survival during drought.

Conclusions

Theoretical work on drought impacts on phloem transport indicates that the hydraulic conductivity between the xylem and the phloem, and between phloem conduits and their immediate environment determines how and when phloem transport becomes impaired during drought. Whether these predictions match the reality requires more experimental work on phloem anatomy and function, especially under drought conditions. In the few studies that have addressed phloem transport during drought, integrity of the phloem seems to be essential for plant survival and it comes out as one of the best predictors of plant survival time. However, more studies on whether and how plants might promote or control phloem integrity during drought are needed before the true impacts of phloem transport on plant survival during drought can be assessed.