The Effects Of Overexpression Of Small Heat Shock Proteins On Chilling-Tolerance And Storage-Life In Tomato Fruit

Tomato is indigenous to the tropics and belong to chilling sensitive plants. long-termstorage at low temperature induces chilling injury in tomato fruit. Chilling injury limitsstorage life and leads to significant degradation of produce quality. People have focused onthe ways to alleviate CI symptoms and improve fruit quality. In 1985, Hirose first reportedthat heat-treatment can reduce chilling injury in fruit, and this phenomenon is termed as heatshock induced chilling tolerance.In 1996, Adnan Sabehat first reported the relationship between the persistence ofheat-shock proteins and chilling tolerance in plant tissue. Later, more and more researchesproved that chilling tolerance of fruit increase with the expression of HSPs, such as ClassIIsHSP,CP sHSP,HSP70 and HSP90.To study the involvement of the four sHSP(ER sHSP, CP sHSP, ClassII sHSP ,MT sHSP)in the acquisition of chilling tolerance, we evaluated the chilling tolerance of transgenictomato fruits by measuring a set of physiology parameters :weight loss,external injury andfirmness. Transgenic and normal tomato fruits were treated in two ways.Our research resultsindicate that individual overexpression of four sHSPs can reduce chilling injury of tomatofruit at various extent. The results were shown as follows:1) Weight loss: Chilling injury can increase respiration rate, and causes degradation ofweight loss. Weight loss is an important parameter of fruit quality. The measurement resultsshow that overexpression of four sHSP can significantly reduce weight loss of tomato fruit;overexpression of ER sHSP and MT sHSP can significantly decrease weight loss in bothtreatments.2) Decay percentage: Decay is mainly caused by bacteria. These bacteria can not infectthose healthy tissue, but parasitize in dysfunctional part caused by chilling injury. The rottonextent can reflect the chilling injury of fruit. The results show that rotten extent is largely...