杜鹃bHLH转录因子RsMYC2的克隆及在非生物胁迫下的表达分析

Cloning and Expression Analysis of Rhododendron b HLH Transcription Factor Rs MYC2 under Abiotic Stress

杜鹃是杜鹃花科(Ericaceae)杜鹃属(Rhododendron)著名花卉植物,被广泛应用于园林绿化中。杜鹃不仅具有较高的观赏价值,还能食用和药用,具有很高的经济价值。bHLH转录因子家族成员MYC2在植物生长发育、防御反应、逆境响应等过程中发挥重要作用,但该基因在杜鹃中的研究几乎处于空白状态。本研究克隆了杜鹃RsMYC2基因全长编码序列,并对其理化性质及氨基酸序列进行了分析。结果表明,RsMYC2编码氨基酸总量为644个,平均分子量为70.78 kD,理论等电点为5.76,所带阴电残留物数量为81,阳电残留物数量为69。Rs MYC2蛋白含有高度保守的结构域,具有典型的bHLH蛋白家族特征。RsMYC2蛋白和大多数植物中MYC2蛋白一样,属于亲水性蛋白质,不含信号肽,不属于分泌蛋白,定位在细胞核。系统进化分析显示,杜鹃RsMYC2与褐枝猕猴桃ArMYC2同源性最高。本研究也采用实时荧光定量PCR分析了RsMYC2在各种非生物胁迫中的反应,结果显示茉莉酸甲酯、赤霉素和干旱处理抑制RsMYC2基因表达,而高温可显著诱导RsMYC2基因表达,表明杜鹃RsMYC2可响应多种非生物胁迫。本研究为解析杜鹃胁迫应答机制提供了理论基础。

Rhododendron is a famous flower plant in Ericaceae,which is widely used in landscaping.Rhododendron has not only high ornamental value,but also edible and medicinal,thus has high economic value.MYC2 as a member of bHLH transcription factor family,plays an important role in plant growth and development,defense and stress response.However,the research of MYC2 in Rhododendron is almost blank.In this study,the fulllength coding sequence of RsMYC2 was cloned and its physicochemical properties and amino acid sequence were analyzed.The results showed that RsMYC2 encoded 644 amino acids,the average molecular weight was 70.78 kD,the theoretical isoelectric point was 5.76,and the number of negative and positive electric residues was 81 and 69,respectively.The Rs MYC2 protein contained highly conserved domain,which was typical of the bHLH protein family.RsMYC2 was a non-secretory hydrophilic protein,localized in the nucleus and did not contain a signal peptide.Phylogenetic analysis showed that RsMYC2 was highest homologous to AcMYC2 in Actinidia chinensis.The responses of RsMYC2 to various abiotic stresses were also analyzed by real-time fluorescent quantitative PCR.The results showed that methyl jasmonate,gibberellin and drought inhibited the expression level of RsMYC2,while high temperature significantly induced the expression level of RsMYC2,indicating that RsMYC2 could respond to various abiotic stresses in Rhododendrons.This study provided a theoretical basis for analyzing the stress response mechanism of Rhododendron.