Changes in the global climate exert significant abiotic stresses (salinity, drought) and constitute major challenges for crop production. Unlike animals, plants cannot move to escape adverse conditions. Hence, they evolved mechanisms to detect changes in their environment, communicate these to different organs, and adjust development accordingly. One of these adaptations is the phloem, a long-distance trafficking pathway, which is essential for the communication of environmental cues. Determining the nature of signals and the mechanisms by which they are communicated through the phloem will lead to a more complete understanding of how the plant adjusts development in response to stress.
Lipids are known to act as signals at the cellular level. However, their role in long distance signaling has received little attention. It is a new area of research which is expected to contribute new concepts to plant development. To act as long-distance signals, lipids have to be released into the phloem, moved bound to a protein "chaperone", and be detected by a receptor. An earlier study of Arabidopsis phloem exudates revealed lipid-binding proteins with potential roles in performing those functions. Lipases could function in the release of lipids; phloem lipid-associated family protein (PLAFP), a predicted stress-induced lipid-binding protein, could facilitate lipid transport throughout the phloem; PIG-P proteins (subunit P of a phosphatidylinositol N-acetylglucosaminyltransferase) could function as part of a lipid receptor. This project aims to use biochemistry, molecular biology, microscopy, and mass spectrometry to characterize the expression of these proteins in response to abiotic stresses (drought, salt, osmotic), investigate the lipid-binding characteristics, and study the impact changes in lipid-binding and protein expression have on this stress response and the phospholipid profile. The experiments, which will be conducted with a graduate student, undergraduate student, and a high school student, will provide an insight into the mechanism of stress-induced lipid signaling and its effect on the plant's response to our changing environment.
