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橡胶树树皮中的次生乳管是天然橡胶合成和贮存的主要场所。生产上施用乙烯利通过延长橡胶树割胶后的排胶持续时间,调节胶乳代谢,从而达到增产的目的。但目前对于转录复合体关键成员RNA聚合酶Ⅱ在胶乳代谢过程中的动态变化尚不清楚。本研究采用RACE和RT-PCR方法,从橡胶树无性系CATAS7-33-97的胶乳中克隆到编码RNA聚合酶Ⅱ关键亚基RPB11的同源基因,命名为HbRPB11。该基因全长659 bp,包含351 bp的开放阅读框,编码一个由116个氨基酸残基组成的蛋白质。该蛋白质分子量为13.53 k D,理论等电点为5.934。实时荧光定量PCR结果表明,HbRPB11在橡胶树的多个组织中均有表达,其中在成熟叶片和胶乳中的表达量最高,并且受割胶和乙烯利处理显著上调。橡胶树不同种质间的表达模式分析显示HbRPB11基因在橡胶合成效率高的种质中的表达量要显著高于橡胶合成效率低的种质,表明该基因的表达量与橡胶合成效率呈正相关性,有可能作为生产上筛选高效合成橡胶种质材料的分子标记。
Secondary bitumen in rubber tree bark is the main site for the synthesis and storage of natural rubber. The production of ethephon by cutting the plastic rubber tree to extend the rubber after the release of plastic time, adjust the latex metabolism, so as to achieve the purpose of increasing production. However, the dynamic changes of RNA polymerase II, a key member of the transcriptional complex, during latex metabolism are not yet clear. In this study, a homologous gene encoding RPB11, a key subunit of RNA polymerase Ⅱ, was named as HbRPB11 by RT-PCR and RT-PCR from latex of CATAS7-33-97. The gene is 659 bp in length and contains a 351 bp open reading frame encoding a protein consisting of 116 amino acid residues. The protein has a molecular weight of 13.53 kD and a theoretical isoelectric point of 5.934. Real-time PCR results showed that HbRPB11 was expressed in many tissues of the rubber tree, among which, the highest expression was found in mature leaves and latex, and was significantly up-regulated by taurine and ethephon. The analysis of the expression pattern of different tree species revealed that the expression level of HbRPB11 gene in germplasm with high efficiency of rubber synthesis was significantly higher than that of the low germplasm of rubber synthesis, indicating that the expression level of HbRPB11 was positively correlated with the efficiency of rubber synthesis. It may be used as a molecular marker for the screening of efficient synthetic rubber germplasm materials.