Temperature and plant hormones alter gene expression and cell wall components of tomato

Fruit firmness is an important index affecting the shelf life of tomato fruits. The softening speed of the fruit may directly affect senescence, preservation, and transportation. Temperature control and treatment with the ethylene inhibitor 1-methylcyclopropene (1-MCP) are the main approaches to relieve the softening speed and improve the shelf life of fruits. In this experiment, the changes in cell wall components and the expression of cell wall metabolism-related genes were measured after different temperature and hormone treatments. The expression of ethylene synthesis and signal transduction-related genes after different temperature treatments was also analyzed. Results showed that the concentrations of cellulose, hemicellulose, and pectin were different under various treatments compared with control. Several genes related to cell wall metabolism, such as SlCel4, SlXET16-F1, SlXETB1-F2, SlXETB2-F2, SlXTH3-F1, SlXTH9-F1 and SlTBG7, exhibited difference in their expression level under various temperature, ethylene and 1-MCP treatments. All seven genes were downregulated at 12.5 degrees C and 1-MCP treatment compared with control. In addition, the expression of ethylene synthesis and signal transduction-related genes, including ACO5, SAMS1, SAMS2, SAMS3, ETR, EBF1, EBF2, EIL1, ERF1A and PTI5, showed variation at 4 degrees C, 12.5 degrees C, and 25 degrees C, and they were all downregulated at 4 degrees C. These results suggested that temperature and ethylene could affect the expression of cell wall metabolism-related genes, thus influencing cell wall metabolism. Intermediate temperature control and 1-MCP treatment were beneficial for delaying the ripening and senescence of tomato fruits.