High triacylglycerol turnover is required for efficient opening of stomata during heat stress in Arabidopsis

SUMMARY Heat stress triggers the accumulation of triacylglycerols in Arabidopsis leaves, which increases basal thermotolerance. However, how triacylglycerol synthesis is linked to thermotolerance remains unclear and the mechanisms involved remain to be elucidated. It has been shown that triacylglyce...

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Published in:	The Plant journal : for cell and molecular biology Vol. 115; no. 1; pp. 81 - 96
Main Authors:	Korte, Pamela, Unzner, Amelie, Damm, Theresa, Berger, Susanne, Krischke, Markus, Mueller, Martin J.
Format:	Journal Article
Language:	English
Published:	England Blackwell Publishing Ltd 01-07-2023
Subjects:	Acid production Amino acids Arabidopsis Arabidopsis thaliana Carbohydrates Catabolism Degradation fatty acid respiration Fatty acids Heat stress Heat tolerance Oxidation Stomata stomatal opening Synthesis Temperature effects Temperature tolerance triacylglycerol turnover tricarboxylic acid cycle Triglycerides Arabidopsis thaliana stomatal opening heat stress tricarboxylic acid cycle triacylglycerol turnover fatty acid respiration
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Summary:	SUMMARY Heat stress triggers the accumulation of triacylglycerols in Arabidopsis leaves, which increases basal thermotolerance. However, how triacylglycerol synthesis is linked to thermotolerance remains unclear and the mechanisms involved remain to be elucidated. It has been shown that triacylglycerol and starch degradation are required to provide energy for stomatal opening induced by blue light at dawn. To investigate whether triacylglycerol turnover is involved in heat‐induced stomatal opening during the day, we performed feeding experiments with labeled fatty acids. Heat stress strongly induced both triacylglycerol synthesis and degradation to channel fatty acids destined for peroxisomal ß‐oxidation through the triacylglycerol pool. Analysis of mutants defective in triacylglycerol synthesis or peroxisomal fatty acid uptake revealed that triacylglycerol turnover and fatty acid catabolism are required for heat‐induced stomatal opening in illuminated leaves. We show that triacylglycerol turnover is continuous (1.2 mol% per min) in illuminated leaves even at 22°C. The ß‐oxidation of triacylglycerol‐derived fatty acids generates C2 carbon units that are channeled into the tricarboxylic acid pathway in the light. In addition, carbohydrate catabolism is required to provide oxaloacetate as an acceptor for peroxisomal acetyl‐CoA and maintain the tricarboxylic acid pathway for energy and amino acid production during the day. Significance Statement Heat stress‐induced accumulation of triacylglycerols in Arabidopsis leaves increases basal thermotolerance. However, how triacylglycerol synthesis is linked to thermotolerance remains unclear. We show that fatty acids are channeled from membranes through the triacylglycerol pool to peroxisomes to produce acetyl‐CoA, which enters the tricaboxylic acid pathway for amino acid and energy production. Heat stress increases the flux of fatty acids through this pathway, which is required for efficient stomatal opening for transpirational cooling.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0960-7412 1365-313X
DOI:	10.1111/tpj.16210