巴西橡胶树CAMTA转录因子全基因组鉴定与表达分析

Genome-wide Identification and Expression Analysis of the CAMTA Family in Rubber Tree(Hevea brasiliensis)

钙调蛋白结合转录激活因子(Calmodulin-binding transcription activator, CAMTA)是一类存在于真核生物中结构保守的重要钙调素结合蛋白,广泛参与植物的胁迫应答、生长发育及激素信号转导等生物学过程。本文以巴西橡胶树(Hevea brasiliensis)为研究对象,从全基因组水平鉴定到8个橡胶树HbCAMTA基因,并对这些基因的理化性质、基因结构、表达模式、启动子区调控元件进行分析。结果显示,该基因家族所有成员均定位于细胞核内,编码蛋白均为亲水性蛋白,分子量在104.34~121.99 kD之间,等电点在5.32~7.83之间;家族基因根据蛋白序列同源性可以分成4个亚组,亚组成员在基因结构、保守基序数目和相对位置等方面具有较高相似性。调控HbCAMTA的miRNA预测分析显示,每个家族成员受到至少3个miRNA调控。表达分析结果显示,HbCAMTA在不同组织的表达有明显的差异,在叶片中随着叶片的发育表达不断上调,在成熟期或变色期达到最高的表达水平;除HbCAMTA2外,乙烯刺激未能显著诱导橡胶树其他CAMTA基因的表达,而低温可以显著诱导HbCAMTA的上调表达。HbCAMTA1是胶乳、叶片、根、树皮、雄花、雌花以及叶片整个发育过程(古铜期、变色期、淡绿期、成熟期)中最高表达的基因家族成员,表明其具有非组织特异性的基础生物学功能。HbCAMTA3在种子中表达水平最高且受低温胁迫诱导显著上调表达,表明其在响应低温胁迫过程中具有重要的作用。HbCAMTA7在大多数组织、乙烯处理、低温胁迫处理以及叶片不同发育时期均是最低表达。本研究初步揭示了橡胶树CAMTA家族成员的理化特征和表达特性,为进一步阐明该基因功能奠定了重要的基础。

Calmodulin-binding transcription activators(CAMTAs)are important proteins with a conserved calmodulinbinding domain,which are widely involved in biological processes such as stress response,growth and development,and hormone signalling in plant.In this study,we identified eight HbCAMTAs screening the genome-wide of the rubber tree and analyzed physicochemical properties,gene structures,regulatory elements,gene expression patterns,and so on.The results showed that all HbCAMTAs were located in the nucleus,and predicted as hydrophilic proteins with molecular weight from 104.34 to 121.99 kD and isoelectric points between 5.32 and 7.83.The sequence homology analysis showed that HbCAMTAs could be divided into four subclades,and each one had similar gene structure,conserved domains.Furthermore,each HbCAMTA was potentially regulated by at least three miRNAs.Expression analysis indicated that the expression of HbCAMTAs differed significantly in different tissues,and the expression was continuously up-regulated in leaves with the development of leaves and reached the highest expression level at mature or palegreen.Except for HbCAMTA2,ethylene stimulation failed to significantly induce the expression of other CAMTA genes in rubber tree while low-temperature could significantly induce the up-regulated expression of HbCAMTAs.HbCAMTA1 was constitutively expressed in all samples,and also mostly expressed in latex,leaves,roots,bark,male and female flowers,and four different leaf developmental stages(Bronzite,Changecolor,Palegreen,and Mature),which suggesting its fundamental function in rubber tree.HbCAMTA3 was expressed at the highest level in the seeds and was significantly up-regulated by low temperature stress,indicating its important role in response to low temperature stress.HbCAMTA7 was undetectably express in all investigated samples including different tissues,leaf developments,and treatments.Finally,this study would provide important information for further revealing the function of HbCAMTAs in rubber tree.