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United States Department of Agriculture

Agricultural Research Service

Research Project: Molecular Genetic Analysis of Abiotic Stress Tolerance and Oil Production Pathways in Cotton, Bioenergy and Other Industrial Crops

Location: Plant Physiology and Genetics Research

Title: Leaf cuticular lipids on the Shandong and Yukon ecotypes of saltwater cress, eutrema salsugineum, and their response to water deficiency and impact on cuticle permeability

Authors
item Xu, Xiaojing -
item Feng, Jinchao -
item Lu, Shiyou -
item Lohrey, Gregory
item An, Huiling -
item Zhou, Yijun -
item Jenks, Matthew

Submitted to: Physiologia Plantarum
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 24, 2013
Publication Date: N/A

Interpretive Summary: Understanding the role of the plant cuticle in drought stress response will provide important clues toward crop improvement, especially as water supplies for irrigation deplete worldwide. We report here that water deficit stress has a dramatic effect on leaf cuticular waxes and cutin monomers, and traits associated with cuticle permeability and drought tolerance, in a novel plant species known to possess extreme drought tolerance, Eutrema salsugineum. Dramatic variation in this response was observed for two diverse ecotypes within this species, Shandong and Yukon. Although Shandong has more visual wax deposition than Yukon, wax amounts on non-stressed Yukon leaves were actually 4.6-fold higher than on Shandong. Drought stress had different effects on the ecotypes, with wax alkanes being induced primarily on Yukon, and acids being induced on Shandong. With or without stress, more abundant cuticle lipids were generally associated with lower water loss rates, lower chlorophyll efflux rates, and an extended time before water-deficitinduced wilting. Overall, Yukon has more cuticle lipids and was much more drought tolerant than Shandong. In response to water deficit, Shandong showed elevated transcription of genes encoding elongase subunits, consistent with the higher stress induction of acids by Shandong. Yukon’s higher induction of CER1 and CER3 transcripts may explain why alkanes increased most on Yukon after water deficit. Eutrema, with its diverse cuticle lipids and responsiveness, provides a valuable genetic resource for identifying new genes and alleles effecting cuticle metabolism, and lays groundwork for studies of the cuticle’s role in extreme stress tolerance.

Technical Abstract: The impact of water deficit stress on leaf cuticular waxes and cutin monomers, and traits associated with cuticle permeability, were examined in Shandong and Yukon ecotypes of Eutrema salsugineum (syn. Thellungiella salsuginea). Although Shandong exhibits glaucous leaves, and Yukon is non-glaucous, wax amounts on nonstressed Yukon leaves were 4.6-fold higher than on Shandong, due mainly to Yukon’s 8.0-fold higher wax fatty acids, especially the C22 and C24 acid homologues. Water deficit caused a 26.9% increase in total waxes on Shandong leaves, due mainly to increased C22 and C24 acids; and caused 10.2% more wax on Yukon (though this not highly significant), due mainly to a significant increase in wax alkanes. Total cutin monomers on non-stressed leaves of Yukon were 58.3% higher than on Shandong. Water deficit caused a 28.2% increase in total cutin monomers on Shandong, whereas total cutin monomers were not induced on Yukon. With or without stress, more abundant cuticle lipids were generally associated with lower water loss rates, lower chlorophyll efflux rates, and an extended time before water-deficit-induced wilting. In response to water deficit, Shandong showed elevated transcription of genes encoding elongase subunits, consistent with the higher stress induction of acids by Shandong. Yukon’s higher induction of CER1 and CER3 transcripts may explain why alkanes increased most on Yukon after water deficit. Eutrema, with its diverse cuticle lipids and responsiveness, provides a valuable genetic resource for identifying new genes and alleles effecting cuticle metabolism, and lays groundwork for studies of the cuticle’s role in extreme stress tolerance.

Last Modified: 11/23/2014
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