Total RNA was extracted from tomato fruits using RNAprep Pure Plant Kit (Tiangen, Beijing, China) according to the manufacturer’s protocol and then the quality of total RNA was tested by agarose-formaldehyde gel electrophoresis. Without DNA contamination and detectable degradation of 26S and 18S rRNA, the RNA could be used for next preparation of cDNA synthesis by reverse transcriptase powerscriptTM according to the manufacturer’s protocol (Tiangen, Beijing, China). The cDNA could be used as a template to quantify target gene expression level