Molecular Mechanism Of The Calmodulin-like Protein SlCML19 To Regulate The Chilling Tolerance Of Postharvest Tomato

Tomato（Solanum lycopersicum L.）are non-cold domesticated plants that originate in the tropics and are vulnerable to low temperatures at all stages of growth and development.Especially,the tomato fruit after harvest is sensitive to the temperature response,but the mechanism of how the temperature affects the response of tomato fruit to the low temperature stress by calcium signal is little known.Calmodulin-like（CML）is a plant-specific protein that can respond to a variety of stresses by feeling changes in intracellular calcium concentration and participating in the process of plant growth and development.In the previous study,we screened a gene encoding Calmodulin-like protein,SlCML19,which had a high expression during the mature stage of tomato and a sharp decrease in expression during low-temperature storage.The main findings are as follows:1 Gene structure analysis revealed that the length of SlCML19（NO.in SGN database:Solyc02g094000）is 426 bp,containing one extron and one intron and encoding a polypeptide of 131 amino acids.Based on the analysis of protein conserved domain,the protein encoded by this gene contained EF handing domain,which can sense and bind Ca²⁺.2 This paper analyzed the homology of tomato,rice and arabidopsis calmodulin family and calmodulin-like family by comparing the available data.The results shown that SlCML19 gene has close evolutionary relationship with some members of rice and arabidopsis calmodulin family.3 Light responsive elements,phytohormone-responsive elements,stress-responsive elements and tissue specific expression elements were found in the promoter region.4 The spatial and temporal expression pattern were analysed hrough online websites and Real-time PCR.The results suggested that SlCML19 mostly expressed in root and fruit.Moreover,the gene highly expressed in the orange fruit stage during the whole fruit maturing progress.5 Genetic positive plants of T0 generation were got through plant tissue culture.The transgenetic fruits of T2 generation were picked in green maturing period and stored at 4°C for 21 days before recovery treatment for 14 days.The cold damage symptoms of overexpresssion fruit were significantly alleviated,suggesting that SlCML19 may be involved in the postharvest regulation of resisting cold damage.6 Through the determination of physiological indexes of postharvest transgenetic fruit under cold condition,it is preliminarily speculated that SlCML19 could decrease the contents of fruit pigments and decrease the content of H₂O₂by promoting the activity of the antioxidant enzyme CAT.7 Yeast two-hybrid and Bi FC assay showed that Sl UMP1 can interact with SlCML19.The results of this study can provide a theoretical basis for revealing the molecular mechanism of postharvest tomato fruit in response to low temperature stress and for controlling the quality of postharvest tomato fruit.