Journal
MOLECULAR PLANT
Volume 6, Issue 6, Pages 1781-1794Publisher
CELL PRESS
DOI: 10.1093/mp/sst072
Keywords
abiotic/environmental stress; oxidative and photo-oxidative stress; salinity; protein traffic and secretion; gene expression; Arabidopsis
Categories
Funding
- Israel Science Foundation (ISF)
- Direct For Biological Sciences
- Div Of Molecular and Cellular Bioscience [1051646] Funding Source: National Science Foundation
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Phosphatidylinositol 5-phosphatases (5PTases) that hydrolyze the 5' position of the inositol ring are key components of membrane trafficking system. Recently, we reported that mutation in At5PTase7 gene reduced production of reactive oxygen species (ROS) and decreased expression of stress-responsive genes, resulting in increased salt sensitivity. Here, we describe an even more salt-sensitive 5ptase mutant, At5ptase9, which also hydrolyzes the 5' phosphate groups specifically from membrane-bound phosphatidylinositides. Interestingly, the mutants were more tolerant to osmotic stress. We analyzed the main cellular processes that may be affected by the mutation, such as production of ROS, influx of calcium, and induction of salt-response genes. The At5ptase9 mutants showed reduced ROS production and Ca2+ influx, as well as decreased fluid-phase endocytosis. Inhibition of endocytosis by phenylarsine oxide or Tyrphostin A(23) in wild-type plants blocked these responses. Induction of salt-responsive genes in wild-type plants was also suppressed by the endocytosis inhibitors. Thus, inhibition of endocytosis in wild-type plants mimicked the salt stress responses, observed in the At5ptase9 mutants. In summary, our results show a key non-redundant role of At5PTase7 and 9 isozymes, and underscore the localization of membrane-bound PtdIns in regulating plant salt tolerance by coordinating the endocytosis, ROS production, Ca2+ influx, and induction of stress-responsive genes.
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