Abstract:

To explore the role of peroxidase（POD）gene family members under stress conditions in apples,51 apple POD（MdPOD）family members were identified through multiple sequence alignments in which the reported Arabidopsis thalianaPOD genes were adopted,and their expression under stresses are analyzed. The results show that the 51 family members scatter in 13 chromosomes,encoding 95 to 1 433 amino acids,protein molecular weight ranges 10.18 to 161.02 kD,and isoelectric point（pI）ranges from 4.36 to 9.90. Further analysis indicates that the gene family is divided into six subfamilies,and the number of exon is 1 to 40. Selective pressure analysis shows that 20 gene pairs are subjected to purification selection in the evolutionary process. Subcellular localization shows that MDPOD15 is mainly presented in the cell membrane,cytoplasm,nucleus and chloroplast. The expression profile of gene chips displays that MdPOD are highly expressed in apple’s flowers,leaves and fruits. Real-time quantitative PCR （qRT-PCR）indicates that the expressions of most genes increased after ABA treatment for 2 h,and then decreases. Under PEG treatment,the expressions of 51 MdPODgenes firstly increase and reach the peak value at 12 h,while under the NaCl treatment,the expressions of MdPOD genes increase with the prolongation of time and reach the peak value at 24 h. The transient expression of MdPOD15 in tobacco leaves shows that MdPOD15 is expressed in the cell wall,cytoplasm and nucleus,and the overexpression of MdPOD15 in apple callus can mitigate the degree of cell damage caused by abiotic stress. Therefore,MdPOD genes may play different roles in different periods of time under different abiotic stresses.

Key words: apple, POD gene family, abiotic stress, expression analysis