Expression Analysis Of Cold Shock Protein Genes Under Low Temperature Stress In Pepper And Changes Of Physiological Indexes

Pepper(Capsicum annuum L.)was native to Central and South America.The optimum growth temperature is between 20 ℃-27 ℃.The growth and development of pepper will be inhibited if the temperature is below 12 ℃ or above 30 ℃.Therefore,the screening of low temperature resistant pepper varieties as the low temperature varieties of pepper breeding and low temperature mechanism studying lay the foundation and the study of pepper cold shock protein gene CaCSPs is the basis for the use of transgenic technology to improve the low temperature resistance of pepper.In this study,the low temperature resistant materials and cold sensitive materials were identified by comparing the low temperature resistance ability of 44 test materials at seedling stage and adult-plant stage,The activities of SOD,POD and CAT,and the contents of soluble sugar and proline of two materials were changed at low temperature of 4 ℃.The gene expression quantity of CaCSP1,CaCSP2,CaCSP3 and CaCSP4 were detected by RT-PCR at different temperatures at 4 ℃.The main contents were as follows:1.Identify low temperature resistant materials and cold sensitive materials.Among the 44 test materials,A185,A187,A048 and A312 had no obvious water loss and waterlogging at seedling stage.A270 and A293 had no obvious chilling injury symptoms at adult-plant stage.Comparing the low temperature resistance ability of seedling stage and adult-plant stage,the low temperature resistant material A270 and cold sensitive material A136 were identified.2.Tested the changes of physiological indexes of pepper.The activity of SOD,POD,CAT,proline and soluble sugar in leaves of A270 and A136 were different at 0 h,6 h,12 h and 24 h at low temperature of 4 ℃:A270 and A136 SOD activity and soluble sugar content increased with the time.POD activity decreased with the prolongation of time.CAT activity increased first and then decreased,and the activity was the highest at 6 h.In general,the five physiological and biochemical indexes of A270 were higher than those of A136 under low temperature stress.3.Identified and analysed the members of the CSP gene family of pepper.Using the whole genome sequence of pepper,the local BLAST database was constructed.The CSP protein sequence of pepper was screened by Hmmer 3.0 from Pfam.The local BLAST search was performed on Arabidopsis thaliana AtCSP family gene sequence.Combine the above two-part results,removing the repeat gene,and using Pfam and NCBI-CDD to predict the protein structure.Construct phylogenetic tree and analysis of protein conserved domain sequences.4.Determined the real-time expression of CaCSP gene.The results showed that the expression of CSP gene was significantly different from that of A270 and A136 at 0 h,1 h,2 h,4 h,6 h,12 h and 24 h,The expression of CaCSP2 was the highest in the leaves of A270,and the highest expression level was in A136.Under low temperature stress,the CSP gene expression of pepper material with different cold resistance was different,and the response time to low temperature stress was not the same.