芥蓝miR172家族成员进化特性比较及时空表达分析

Evolutionary Characteristics and Analysis of miR172 Family Members in Chinese Kale

为了明确植物miR172家族成员的进化特性及其在不同组织部位的表达情况,该研究以芥蓝miR172a家族为例,通过芥蓝miR172a成熟体序列比对、前体(pre-miRNA)二级结构预测、系统发育进化树构建、靶基因预测及实时荧光定量等手段,对芥蓝miR172a和miR172b基因家族的进化特性及其在芥蓝不同组织部位中的表达规律进行分析。结果显示:(1)芥蓝miR172家族存在20个成熟体成员,通过比对发现20条序列都存在一个重叠区域,该区域中ACTAGATC 8个碱基高度保守,并且在芥蓝pre-miR172的3′和5′端均能形成成熟体。(2)mfold预测结果显示,miR172a家族5个前体成员的最小折叠自由能在-54.55^-78.60kal/mol之间,均能自发形成典型、稳定的茎环二级结构。(3)系统发育进化树显示,芥蓝miR172a家族的前体成员具有一定的保守性和多样性,并与番木瓜pre-miR172a亲缘关系较近。(4)靶基因预测发现芥蓝miR172a共有13个不同靶标基因,多个成员也可以作用于相同靶标基因。(5)实时荧光定量PCR显示,芥蓝pre-miR172a和pre-miR172b家族不同成员在不同组织部位表达量差异显著,10个成员在9个组织部位中的表达各不相同。其中,芥蓝pre-miR172a-1、pre-miR172a-2、premiR172a-3和pre-miR172b在芥蓝荚中大量表达;pre-miR172b-5p和pre-miR172b-5p-2在芥蓝花中大量表达。研究表明,miR172在芥蓝花和荚的发育过程中起着重要的作用。

In order to understand the evolutionary characteristics of miR172 family members and their expression in different tissues,we explored miR172 family members of Chinese kale in this study.The evolution characteristics of miR172s and their expression patterns in different tissues were analyzed.The results showed that:(1)there were 20 miR172 members in Chinese kale.By comparison,all 20 sequences have an overlapping region,in which 8 bases of ACTAGATC are highly conserved.(2)The results of mfold prediction showed that folding free energy of five precursor components of miR172a family ranges from-54.55 kal/mol to-78.60 kal/mol,both of which could spontaneously form a typical and stable stem-loop secondary structure.(3)Phylogenetic tree shows that the miR172 in Chinese kale is closely related to Carica papaya miR172.(4)A total of 13 different genes were predicted to be targets of miR172a in Chinse kale and multiple members could also target the same gene.(5)The expression of different members of pre-miR172a and pre-miR172b was significantly different in different tissues.The pre-miR172a-1,pre-miR172a-2,pre-miR172a-3 and pre-miR172b were highly expressed in pods of Chinese kale and the pre-miR172b-5p and pre-miR172b-5p-2 were highly expressed in flowers,indicating that miR172 plays an important role in the development of Chinese kale flowers and pods.