苹果MdPEPC基因家族鉴定及在腋芽萌发中的作用

Genome-wide identification and effect of MdPEPC family genes during axillary bud outgrowth in apple (Malus domestica Borkh.)

摘要:

磷酸烯醇式丙酮酸羧化酶（phosphoenolpyruvate carboxykinase，PEPC）家族蛋白普遍存在各种植物中，在光合碳同化过程中起到重要作用，同时具有多种非光合生物学功能，但PEPC基因在苹果（Malus domestica Borkh.）中尚未研究报道。本研究以苹果新基因组数据为基础，利用生物信息学方法对苹果PEPC家族成员（the members of apple PEPC family，MdPEPC）进行鉴定，并对其在不同组织中的表达谱以及去顶和细胞分裂素噻重氮苯基脲（thidazuron，TDZ）处理后苹果腋芽转录组中的表达模式进行分析，以期探究MdPEPC基因在参与苹果腋芽萌发中的作用。结果表明，苹果MdPEPC家族共有6个成员，分布于6条不同的染色体上，且理化特征较为相似；系统进化树及序列比对分析显示其可分为2个亚组（Group Ⅰ和Group Ⅱ），其中Ⅰ组含4个MdPEPC家族成员，属于植物型PEPCs，而MdPEPC4和MdPEPC5则与拟南芥细菌型AtPPC4聚类到Ⅱ组；共线性分析表明，MdPEPC成员之间不存在串联重复，含7对片段重复；顺式作用元件分析显示，MdPEPC家族成员不仅受光和逆境等影响，还受多种激素综合调控；表达谱显示，除MdPEPC4和MdPEPC5外，其他植物型MdPEPC在不同组织中均有表达。转录组数据分析表明，去顶和TDZ处理后MdPEPC1和MdPEPC3表达量上调，而MdPEPC2则在处理后48 h明显下调表达。综上所述，本研究通过对苹果MdPEPC家族的鉴定和分析，筛选出MdPEPC1、MdPEPC2和MdPEPC3作为调控苹果腋芽萌发的候选基因，以便后期对其进行深入研究。

Abstract:

The PEPC family proteins are ubiquitous in various plants and play an important role in the process of photosynthetic carbon assimilation and have many non-photosynthetic biological functions. However, PEPC genes have not been reported in apple. In this study, the members of apple MdPEPC family were identified based on the new apple genome data by bioinformatics analysis, and their expression patterns in different tissues and the apple axillary bud transcriptome treated by decapitation and TDZ (cytokinin) were analyzed in order to explore the role of MdPEPC genes in apple axillary bud outgrowth. The results showed that 6 MdPEPC family members were identified in apple, which distributed on 6 different chromosomes, and had similar physicochemical characteristics. Phylogenetic tree and sequence alignment analysis showed that the MdPEPC could be divided into two subgroups (Group Ⅰ and Group Ⅱ), in which four members in MdPEPC family were clustered into Group Ⅰ, belonging to plant-type PEPCs. However, MdPEPC4 and MdPEPC5 were clustered into Group Ⅱ with AtPPC4, belonging to bacterial-type PEPCs. There were 7 pairs of fragments repeats among MdPEPC members, but no tandem repeats existed. The promoter cis-acting element analysis showed that MdPEPC genes were not only affected by light and stress, but also regulated by multiple hormones. The expression profiles showed that all MdPEPCs except MdPEPC4 and MdPEPC5 were expressed in different apple tissues. Transcriptome data analysis showed that the expression levels of MdPEPC1 and MdPEPC3 were up-regulated after decapitation and TDZ treatment, whereas MdPEPC2 was significantly down-regulated at 48 h after treatments. In conclusion, MdPEPC1, MdPEPC2 and MdPEPC3 were selected as the candidate genes involved in axillary bud outgrowth regulation for further study.