Triacylglycerol lipase a10 (SlTGLa10) gene negatively regulates cold tolerance, vegetative and reproductive growth in tomato

Abstract

Triacylglycerol (TAG) Lipases (TGLs) are the main enzymes involved in triacylglycerol catabolism. TGLs hydrolyze long-chain fatty acid triglycerides, which are involved in plant development and abiotic stress responses. Cold stress severely affects the yield of tomato plants; however, the mechanisms are not clear. Here, we show that Triacylglycerol Lipase a10 (SlTGLa10) negatively regulates cold tolerance and growth in tomato. Compared to wild-type (WT) plants, SlTGLa10 overexpression (OE) plants showed increased sensitivity to cold stress associated with higher levels of malondialdehyde, ion leakage and lipid peroxidation, lower activities of antioxidant enzymes, and reduced expression of several cold-responsive genes (SlCBF1, SlDRCi7, etc.) while the SlTGLa10 knockdown (KD) plants were moderately more cold-tolerant than WT. Expression of lipid transport and metabolism-related genes, and the TAG contents and composition were differentially affected in the OE and KD plants. The OE plants exhibited lighter seed weight, inhibited seed germination, shorter shoots and smaller fruits than WT plants, whereas KD plants showed the opposite phenotypes (heavier seeds, improved seed germination, longer shoots and larger fruits compared to the WT plants). Although our data indicated that SlMYB16 might not bind to conventional MYB-recognition sites in the promoter region of SlTGLa10, the transcript levels of SlTGLa10 were reduced in tomato plants overexpressing SlMYB16. The results suggest that SlMYB16 may function as a negative factor for the transcription of SlTGLa10. Overall, our work emphasizes the importance of SlTGLa10 for cold tolerance and growth and development in tomato and can provide a straightforward breeding strategy to develop crops that are cold-resistant and high-yielding.