Precursor feeding studies and molecular characterization of geraniol synthase establish the limiting role of geraniol in monoterpene indole alkaloid biosynthesis in Catharanthus roseus leaves
Precursor feeding studies and molecular characterization of geraniol synthase establish the limiting role of geraniol in monoterpene indole alkaloid biosynthesis in Catharanthus roseus leaves
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DOI：
10.1016/j.plantsci.2015.07.007
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发表时间：
2015-10-01
期刊：
影响因子：
5.2
通讯作者：
Nagegowda, Dinesh A.
中科院分区：
文献类型：
--
作者：
Kumar, Krishna;Kumar, Sarma Rajeev;Nagegowda, Dinesh A.
单萜吲哚生物碱（MIA）通常衍生自异胡萝卜苷，其通过萜部分裂叶皂苷和吲哚部分色胺的缩合形成。关于萜类或吲哚类化合物在长春花细胞培养中对MIA产生的限制，有相互矛盾的报道。香叶醇合成酶（GES）合成香叶醇是裂叶茄素生物合成的第一步。在本研究中，C.用香叶醇而不是色氨酸（色胺的前体）处理玫瑰叶增加了MIA长春质碱和文多灵的积累，表明香叶醇在MIA生物合成中的限制。这进一步验证了分子和植物特性的C玫瑰GES（CrGES）。CrGES转录本表现出叶和芽特异性表达，并诱导茉莉酸甲酯。CrGES的病毒诱导的基因沉默（VIGS）显著降低了MIA含量，其在香叶醇饲喂后恢复到接近WT水平。此外，CrGES在月季叶片中的过表达增加了MIA含量。CrGES与不同品种叶片中的MIA含量具有相关性。roseus栽培品种，并且相对于其他途径基因具有显著较低的表达。这些结果表明，CrGES的转录调控，因此，在植物香叶醇的可用性在MIA的生物合成中起着至关重要的作用。(C)2015爱思唯尔爱尔兰有限公司版权所有。
The monoterpene indole alkaloids (MIAs) are generally derived from strictosidine, which is formed by condensation of the terpene moiety secologanin and the indole moiety tryptamine. There are conflicting reports on the limitation of either terpene or indole moiety in the production of MIAs in Catharanthus roseus cell cultures. Formation of geraniol by geraniol synthase (GES) is the first step in secologanin biosynthesis. In this study, feeding of C. roseus leaves with geraniol, but not tryptophan (precursor for tryptamine), increased the accumulation of the MIAs catharanthine and vindoline, indicating the limitation of geraniol in MIA biosynthesis. This was further validated by molecular and in planta characterization of C roseus GES (CrGES). CrGES transcripts exhibited leaf and shoot specific expression and were induced by methyl jasmonate. Virus-induced gene silencing (VIGS) of CrGES significantly reduced the MIA content, which was restored to near-WT levels upon geraniol feeding. Moreover, over-expression of CrGES in C roseus leaves increased MIA content. Further, CrGES exhibited correlation with MIA levels in leaves of different C. roseus cultivars and has significantly lower expression relative to other pathway genes. These results demonstrated that the transcriptional regulation of CrGES and thus, the in planta geraniol availability plays crucial role in MIA biosynthesis. (C) 2015 Elsevier Ireland Ltd. All rights reserved.