Abstract: Conserved protein motif of malectin-like receptor kinases（Malectin，Malectin-like and Pkinase）were used to blast the MRLKs from peach （Prunus persica） protein database. RNA-sequencing data was used to analyze the expression of MRLKs in five peach cultivars with different aphid resistance genotype after green peach aphid（GPA）feeding at different time points（0，3，6，9，12，24，48 and 72 h）. In this study，we identified 41 members of the MRLK family in the peach genome，and the MRLK genes were distributed unevenly on 8 chromosomes in peach. The amio acid number is 391–1 035，molecular weight is 44.05–115.09 kD，pI is 5.38–9.16 of the MRLK family numbers of peach. The phylogenetic tree showed that MRLK family were divided into 5 subgroups of Arabidopsis，rice and peach. The members of the peach MRLK family were divided into 3 subgroups（Ⅰ，Ⅱ，Ⅲ）. The members within each sub-group were highly conserved according to the analysis of motifs compositions and exon/intron organizations. Subcellular location prediction analysis showed that all the MRLK members were located on cytoplasmic membrane. Additionally，prediction on cis-acting elements indicated that these genes were likely to be involved in multiple responses stimulated by light，phytohormone，abiotic and biotic stress. After GPA infection，no expressions of 19 members were detected in the five experimental materials mentioned above，and another 15 family members were found to be no differentially expression between‘P5868’with any other materials. After aphid infection，PpMRLK2，PpMRLK9，PpMRLK22，PpMRLK23，PpMRLK24，PpMRLK26 and PpMRLK32 were constitutionally highly expressed in Rm4 type variety‘P5868’. Among them，PpMRLK26 showed the most significant up-regulation. Further analysis indicated that 22 MRLK genes were constitutively expressed in‘P5868’，as they were stably expressed at different times after aphid infection. Therefore，PpMRLK26 can be considered as a potential candidate gene for Rm4 type aphid-resistance in peach.

Key words: Prunus persica, MRLK；bioinformatic analysis, green peach aphid, gene expression