木薯MebZIP7和MebZIP9基因的克隆及其转录活性分析

Cloning and transcription profiling of two basic leucine zipper genes, MebZIP7 and MebZIP9, in cassava

关键词:  木薯  碱性亮氨酸拉链  基因差异表达  淀粉积累

Key words:  cassava (Manihot esculenta Crantz)  basic leucine zipper  gene different expression  starch accumulation

摘要:

为揭示碱性亮氨酸拉链转录因子（Basic leucine zipper，bZIP）家族在木薯块根发育和淀粉积累中的功能。本研究克隆了木薯bZIP基因家族2个成员MebZIP7和MebZIP9，系统分类比较发现它们为A亚族，属于ABF（ABA-response-element-binding factor）类基因，亚细胞定位试验发现它们具有核定位特征。通过实时荧光定量PCR（qPCR）分析证明MebZIP7和MebZIP9在栽培品种块根和叶片中表达显著高于野生型，二者均受外源脱落酸（ABA）诱导，在块根中快速增加10.7和6.3倍，然后下降；叶片中均为4.5倍，时间滞后。进而对于其在大田条件下多个栽培品种和野生型不同发育时期块根及叶片中的表达进行分析，证明MebZIP9在栽培品种发育不同时期块根和叶片中的转录活性均显著高于野生型，且块根中更突出；MebZIP7在块根发育早中期高于野生型。说明ABF类基因参与木薯ABA信号通路且影响块根淀粉积累。

Abstract:

To investigate the function of basic leucine zipper (bZIP) in cassava root development and starch biosynthesis, two members in bZIP family, MebZIP7 and MebZIP9 were cloned and used for a serious of expression analysis in cultivars and wild sub-species under different conditions. Phylogenetic tree analysis ascribed the two members into A subfamily of bZIP family, belonged to abscisic acid response element binding factor (ABF). Sub-cell location confirmed that they appeared inside the nuclear of cell, partly identified their transcription factor feature. Q-PCR screening revealed that the expressions of MebZIP7 and MebZIP9 were significantly higher in storage root and functional leave of the cultivar than those in wild ancestor W14. And both of them were quickly induced by ABA, with 10.7-and 6.3-fold expression in storage root, equally 4.5-fold in leave of cultivar than wild W14 and reached to the peak after one hour and reduced to the initial level after 24 h. Furthermore, their transcriptional activity in timely developing stages under field condition in 3 cultivars and wild W14 were evaluated. It was shown that the MebZIP9 was not only in storage root but also in leaves remarkable high expressed in those 3 cultivars than in the wild W14. But the expression level of MebZIP7 was not significant different except there were higher expressions in storage root of 90 and 150 d of cultivars. This study indicated that the MebZIPs were involved in ABA signal transduction, which was related to starch accumulation in cassava.