Moot aquaporins as sensors and regulators of plant water tranpsort

摘要

Water flow through plants, is largely regulated by stomata and the efficient use of water is largely governed by regulatory mechanisms impacting on stomata. Our understanding of stomata has allowed enhancement of water use efficiency and yield for a desired quality. However, there are other regulatory sites that govern the distribution of water flow that may be enhanced to deliver a desired agricultural outcome and may also interact with regulation of stomata. The pores that allow water to flow across membranes; the aquaporins, appear to be tightly regulated. A combination of molecular and biophysical techniques has been used to investigate aquaporins within roots and the interaction with shoots. We have found evidence for regulation of aquaporin activity in roots through the second messengers of intracellular pH and pCa, and through direct effects of osmotic potential on aquaporin water permeability. Some aquaporins may also become ion permeable under certain conditions. At the root system level we introduce the diversion of flow hypothesis to explain why aquaporins may be sensitive to hostile soil conditions. At the whole plant level we have evidence that there is a shoot to root signalling mechanism that may balance shoot demand to root capacity for water flow.