杧果果实后熟过程中PME基因家族的鉴定与表达分析

Identification and Expression Analysis of PME Gene Family during Mango Fruit Ripening

为探明影响杧果(Mangifera indica L.)软化的机理、研究果胶甲酯酶(pectin methylesterase,PME)基因家族在杧果果肉中的功能,本研究对‘红象牙’杧果软化期间果实硬度、可溶性固形物含量、微管结构、PME酶活和PME家族表达量进行测定,并对PME基因家族进行生物信息学分析。结果表明,杧果后熟软化过程中伴随着微管骨架的解聚、果实硬度的下降、可溶性固形物含量的升高以及PME活性的降低。在‘红象牙’杧果基因组中共筛选出51个PME基因,Ⅰ型PME(包含PME和PMEI结构域)基因有24个,Ⅱ型PME(仅含PME结构域)基因有27个。51个PME基因中有22个在后熟期表达,参与果实软化。同时,发现mango030191和mango030421两个基因在后熟期内高表达,可能在抑制果胶降解,抑制果实软化中发挥重要作用。Ⅰ型和Ⅱ型PME基因在系统发育树中占据不同分支,第1~2分支都是Ⅰ型PME基因,第3分支都是Ⅱ型PME基因。Ⅰ型和Ⅱ型PME基因拥有各自的基序、保守结构域、内含子外显子特征。本研究鉴定并提供了杧果PME基因家族成员的基本信息,为阐明杧果后熟过程中PME基因的功能提供理论依据。

In order to explore the mechanism affecting mango softening and study the functions of PME gene family in mango fruit pulp,this study uses'Hongxiangya'mango as material to determine the fruit hardness,soluble solid content,microtubule structure,PME enzyme activity and expression during the softening and to conduct bioinformatics analysis of PME gene family.The results showed that the process of mango fruit ripening and softening is accompanied by the depolymerization of the microtubule skeleton,the decrease of fruit hardness,the increase of soluble solid content and the decrease of PME activity.A total of 51 PME genes are screened in the'Hongxiangya'mango genome including 24 typeⅠPME genes(including PME and PMEI domains)and 27 typeⅡPME genes(only PME domains).21 of the 51 PME genes are expressed at post-ripening stage and are involved in mango fruit softening.At the same time,it is found that two genes,mango030191 and mango030421,are highly expressed in the post-ripening period,which play an important role in inhibiting pectin degradation and fruit softening.TypeⅠand typeⅡPME genes occupy different branches in the phylogenetic tree.Branches 1~2 are typeⅠPME genes,and branch 3 is typeⅡPME genes.TypeⅠand TypeⅡPME genes have their own motifs,conserved domains,introns and exons.This study identifies and provides the basic information about PME gene family members of mangoes,and provides a theoretical basis for elucidating the functions of PME genes in the process of mango post ripening.