张世鑫 吴绍华 杨署光 晁金泉 李招娣 田维敏

摘 要：转录中介体（mediator，Med）中的Med25基因在植物的组织发育、器官发生、胁迫响应以及调控茉莉酸（JA）信号途径等方面起重要调控作用。该文在巴西橡胶树基因组序列中找到了橡胶树Med25基因的序列，通过RT-qPCR和RACE技术克隆HbMed25基因的全长序列并进行生物信息学预测分析结果显示，HbMed25基因包含2 655 bp的开放阅读框，编码884个氨基酸，蛋白分子量为95 kD，理论等电点为8.68，疏水性蛋白，亚细胞定位最可能为细胞核。Real-time PCR分析结果显示，HbMed25基因在树皮中表达量最高，在植物激素JA处理的形成层和胶乳材料中HbMed25基因在处理早期（1 h和2～4 h）上调表达，受割胶处理HbMed25基因在处理早期上调表达且对高产的橡胶树品系（CATAS 8-79和CATAS 7-33-97）的割胶处理响应更明显。综上结果认为，HbMed25基因极大可能参与了JA信号途径的调控，对阐明JA诱导橡胶树次生乳管分化的分子调控机制具有促进作用。

关键词：巴西橡胶树，HbMed25，表达分析，茉莉酸信号途径，乳管分化，橡胶合成

中图分类号：Q943

文献标识码：A

文章编号：1000-3142（2021）09-1548-13

Abstract：The Med25 gene in the transcription mediator （Med）plays an important regulatory role in many processes，such as tissue development，organogenesis，stress response，and regulation of jasmonate acid（JA）signaling pathway in plants. The Med25 gene sequence was found in the genome of Hevea brasiliensis，and the full-length sequence of HbMed25 gene was cloned by RT-qPCR and RACE technology，and the biological information was predicted and analyzed. The results were as follows：The HbMed25 gene included an open reading frame for 2 655 bp，encoded 884 amino acids，the molecular weight was 95 kD and theoretical isoelectric point was 8.68，hydrophobic protein，and most likely localized in the nucleus in subcellular localization analysis. Real-time PCR analysis results showed that HbMed25 was the most highly expressed in the bark; HbMed25 was up-regulated at the early stage of treatment （1 h and 2-4 h）in the cambium and latex treated by the plant hormone of JA. After tapping，HbMed25 had the highest expression at the early stage of tapping treatment，and up-regulates expression in high-yield rubber clones（CATAS 8-79 and CATAS 7-33-97）. All the results indicate that HbMed25 is highly likely to participate in the regulation of the JA signal pathway，and it plays a role in promoting the molecular regulation mechanism of JA-induced secondary laticifer differentiation.

Key words：Hevea brasiliensis，HbMed25，expression analysis，jasmonate signaling pathway，laticifer differentiation，rubber synthesis

中介體复合物（mediator，Med）在植物不同组织发育、花期、花的结构、植物抗逆性等方面具有重要作用。例如：Med8、Med17、Med18、Med20A可以调控植物的花期（Kim et al.，2011）;Med18、Med21参与植物响应生物逆境胁迫（Dhawan et al.，2011）;Med16参与植物对非生物的逆境响应（Wathugala et al.，2011）。在众多的Med成员中，Med25的研究相对较多且对基因功能的了解更详细。AtMed25可调控拟南芥中光敏色素信号的PFTI （Wollenberg et al.，2007; Backstrom et al.，2011），在植物响应逆境胁迫过程中具有显著作用（Elfving et al.，2011）。AtMed25的缺失突变体植株细胞体积变大、细胞数目增加，导致植物的器官体积增大;过量表达AtMed25的植株细胞体积变小、细胞数目变少，导致植物器官体积减小。……