香蕉磷酸盐转运蛋白1(PHT1)基因家族的鉴定及表达

Genome-wide identification and expression analysis of PHT1 gene family in banana

磷酸盐转运蛋白1(phosphate transporter 1,PHT1)在植物对磷元素吸收过程中扮演着重要角色.为鉴定香蕉PHT1家族成员和分析它们的表达模式,对香蕉PHT1基因家族(MaPHT1)进行全基因组鉴定和生物信息学分析;并基于转录组数据研究MaPHT1s在有和无印度梨形孢(Piriformospora indica)定殖的根系、45℃和4℃处理的叶片以及自然成熟和乙烯催熟的果实中的表达模式;同时利用实时荧光定量PCR(qRT-PCR)分析部分成员在不同磷浓度处理下有无P. indica定殖的香蕉根系中的表达情况.香蕉中共存在可分为4个亚家族(Group I-IV)的12个MaPHT1s,绝大多数成员含有1-2个外显子,其编码蛋白长度介于517-834 aa,具有10-12个跨膜结构域且均定位于质膜.MaPHT1s中存在1对串联重复基因和4对片段重复基因;启动子区含多种植物激素和逆境胁迫响应的顺式作用元件(cis-acting element)以及14种转录因子的结合位点(transcription factor binding sites,TFBS);MaPHT1s不同亚家族在香蕉不同组织部位表达差异较大,如Group III的MaPHT1-1、1-2和Group II的MaPHT1-7在根系、叶片和果实中均表达;Group IV中MaPHT1-8、1-9和1-11在根系与叶片中高表达.qRT-PCR结果显示:MaPHT1-5、1-7、1-8和1-9受低磷或缺磷诱导,接种P. indica诱导MaPHT1-1、1-5、1-7、1-8和1-9的表达.本研究表明MaPHT1s的表达受激素和逆境调控,不同亚家族成员的表达模式差异较大,推测部分成员在香蕉应答磷胁迫中发挥着重要作用.(图7表3参54)

Phosphate transporter 1(PHT1) plays a key role in Pi uptake and translocation in plants. In this study,we aimed to identify PHT1 family members in bananas and analyze their expression patterns. Whole-genome wide identification and bioinformatics analysis of the MaPHT1 gene family were performed. The expression patterns of MaPHT1 members in roots colonized and non-colonized by Piriformospora indica, in leaves treated at 45 ℃ and 4 ℃, and in natural ripening and ethylene-treated fruits were investigated based on our previous transcriptome data. Moreover, quantitative real-time PCR(qRT-PCR) was used to analyze the expression of some members in P. indica-colonized and non-colonized banana roots treated with different concentrations of phosphorus. In total, 12 MaPHT1s belonging to four subfamilies were identified. Almost all MaPHT1s contained 1–2 exons, and their encoded proteins consisted of 517 to 834 aa. All MaPHT1s contained 10–12transmembrane domains and were predicted to be plasma membrane-located. One pair of tandem replicating genes and four pairs of fragment replicating genes were identified in MaPHT1s. Prediction results of cis-acting elements and transcription factor binding sites(TFBS) showed that there were many phytohormone-and stress-responsive elements and 14 types of TFBS in the promoter regions of MaPHT1s. The mRNA levels of MaPHT1s varied greatly among different organs. For instance, MaPHT1-1, 1-2(belonging to Group III) and 1-7(Group II) were expressed in roots, leaves, and fruits, whereas MaPHT1-8, 1-9 and 1-11(Group IV) showed high expression in roots and leaves. The qRT-PCR results showed that phosphorus deficiency stress induced the expression of MaPHT1-5, 1-7, 1-8, and 1-9 and P. indica inoculation induced the expression of MaPHT1-1, 1-5,1-7, 1-8, and 1-9. The results of this study indicated that the mRNA levels of MaPHT1s could be influenced by plant hormones and stresses, and their functions varied greatly among different members, with some members contributing greatly to the phosphorus deficiency stress response in banana.