桃MRLK家族全基因组鉴定及蚜虫侵染后的表达分析

Genome Wide Identification of MRLK Family Genes and Expression Analysis in Response to Aphid Infection in Peach

以Malectin(PF11721)、Malectin-like(PF12819)和Pkinase(PF07714)保守域全蛋白序列为种子序列,鉴定桃(Prunus persica)基因组中全部MRLK类受体激酶(Malectin receptor-like kinases)家族成员,并利用转录组测序分析桃绿蚜侵染不同时间MRLK在抗蚜和感蚜品系材料中的表达情况。利用生物信息学手段进行分析,共获得41个MRLK家族成员,这些基因分布在桃的8条染色体上。家族成员氨基酸数量介于391~1 035 aa,分子量44.05~115.09 kD,等电点5.38~9.16。分析系统进化树发现拟南芥、水稻和桃的MRLK家族分为5个亚组,其中桃MRLK家族成员分布在Ⅰ、Ⅱ和Ⅲ亚组上。亚细胞定位预测显示该家族成员全部定位在细胞膜上。顺式作用元件预测结果显示该家族成员启动子包含光、激素以及响应生物与非生物胁迫的作用元件。桃绿蚜侵染结果表明,桃MRLK家族中19个基因在5个桃材料中均未表达,15个基因在抗蚜品系‘P5868’与其他4个材料之间无差异表达。Pp MRLK2、Pp MRLK9、Pp MRLK22、Pp MRLK23、Pp MRLK24、Pp MRLK26和Pp MRLK32在抗蚜品系‘P5868’中表达量比其他品系高,其中Pp MRLK26表达量差异显著。进一步分析发现,在抗蚜品系‘P5868’中表达的22个MRLK呈组成型表达,蚜虫侵染处理不会对基因的表达产生影响。综上,推测Pp MRLK26可能调控抗蚜品系‘P5868’的抗蚜性状的形成。

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.