The rice terpene synthase gene Os TPS 19 functions as an ( S )‐limonene synthase in planta, and its overexpression leads to enhanced resistance to the blast fungus Magnaporthe oryzae

作者：Xujun Chen, Hao Chen, Hao Chen, Joshua S. Yuan, Tobias G. Köllner, Yuying Chen, Yufen Guo, Xiaofeng Zhuang, Xinlu Chen, Xinlu Chen, Yong‐jun Zhang, Jianyu Fu, Andreas Nebenführ, Zejian Guo, Feng Chen · 发表于：Plant Biotechnology Journal · 年份：2018 · DOI：10.1111/pbi.12914 · 被引用次数：117 · 研究领域：Plant biochemistry and biosynthesis、Photosynthetic Processes and Mechanisms、Plant Gene Expression Analysis

Rice blast disease, caused by the fungus Magnaporthe oryzae, is the most devastating disease of rice. In our ongoing characterization of the defence mechanisms of rice plants against M. oryzae, a terpene synthase gene OsTPS19 was identified as a candidate defence gene. Here, we report the functional characterization of OsTPS19, which is up-regulated by M. oryzae infection. Overexpression of OsTPS19 in rice plants enhanced resistance against M. oryzae, while OsTPS19 RNAi lines were more susceptible to the pathogen. Metabolic analysis revealed that the production of a monoterpene (S)-limonene was increased and decreased in OsTPS19 overexpression and RNAi lines, respectively, suggesting that OsTPS19 functions as a limonene synthase in planta. This notion was further supported by in vitro enzyme assays with recombinant OsTPS19, in which OsTPS19 had both sesquiterpene activity and monoterpene synthase activity, with limonene as a major product. Furthermore, in a subcellular localization experiment, OsTPS19 was localized in plastids. OsTPS19 has a highly homologous paralog, OsTPS20, which likely resulted from a recent gene duplication event. We found that the variation in OsTPS19 and OsTPS20 enzyme activities was determined by a single amino acid in the active site cavity. The expression of OsTPS20 was not affected by M. oryzae infection. This indicates functional divergence of OsTPS19 and OsTPS20. Lastly, (S)-limonene inhibited the germination of M. oryzae spores in vitro. OsTPS19...