Evaluation Of Heat Tolerance In Different Grape Cultivars And Proteomic Analysis Of Heat Tolerance Difference Between Cultivars

Recently,the application of rain shelters in cultivating grape makes it possible to produce grape in south C hina,where grape industry has been developing rapidly.However,rain shelter causes another problem--high temperature stress inside the shelter in summer,which has become one of the important limiting factors in development of grape industry in south China.Therefore,evaluation of the thermo-tolerance among grape cultivars and screening heat-tolerance ones is of great importance for the development of grape industry in south C hina.In this study,four table grape cultivars including'Oriental Star','Shine Muscat','Summer Black'and'Wink'were used as the experimental materials.The chan ges of photosynthetic performances and morphological structures of the leaf cells under heat stress(45?)were analyzed to evaluate the heat tolerance of different cultivars.Then the proteomes of leaves from two contrast cultivars with different heat tolerance prior to and 5h of heat treatment were analyzed.The results showed that under rain shelter in summer season,mid-day temperature could reach above 40?.Net photosynthetic rate(Pn)in both'Oriental Star'and'Shine Muscat'decreased significantly.The range of decrease in'Shine Muscat'was larger than that in'Oriental Star'.Under simulated high temperature stress in phytotron,the Pn and the maximum photochemical efficiency of PSII(Fv/Fm)decreased with the length of exposure to heat.The reduction in Pn and F_v/F_m in'Oriental Star'was the lowest among all the four cultivars.The cellular structure of mesophylls,especially the ultrastructure of the chloroplasts maintained intact in'Oriental Star'.In contrast,'Shine Muscat'was most heat-sensitive among the four cultivars,with sharpest decline in Pn and F_v/F_m under heat stress.A large number of plastoglobulus and breakdown of thylakoid were observed inside the chloroplasts in the mesophylls of'Shine Muscat'.The heat tolerance of'Summer Black'and'Wink'were betweeen the above-mentioned two cultivars,but'Summer Black'had a slightly better performance under heat stress than'Wink'.We carried out proteomic analysis in'Oriental Star'and'Sine Muscat'with sharpest difference in heat tolerance prior to and after exposure to heat stress.389 differentially expressed proteins(DEPs)under heat shock in'Oriental Star'and 297 in'Shine Muscat'.Among the DEPs,molecular chaperones(especially the sHSP)and redox homeostasis-related proteins(GSTs)were significantly higher in'Oriental Star',which showed that HSPs and GST may play an important role in thermo-tolerance in grapevine.The number of protease which is down regulated under heat treatment in'Oriental Star'are more than that in'Shine Muscat'.The role of these DEPs played in heat tolerance of grapevine need to be further studied.