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

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 Os TPS 19 was identified as a candidate defence gene. Here, we report the functi...

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Veröffentlicht in:Plant biotechnology journal 2018-10, Vol.16 (10), p.1778-1787
Hauptverfasser: Chen, Xujun, Chen, Hao, Yuan, Joshua S., Köllner, Tobias G., Chen, Yuying, Guo, Yufen, Zhuang, Xiaofeng, Chen, Xinlu, Zhang, Yong‐jun, Fu, Jianyu, Nebenführ, Andreas, Guo, Zejian, Chen, Feng
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Sprache:eng
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Zusammenfassung: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 Os TPS 19 was identified as a candidate defence gene. Here, we report the functional characterization of Os TPS 19 , which is up‐regulated by M. oryzae infection. Overexpression of Os TPS 19 in rice plants enhanced resistance against M. oryzae , while Os TPS 19 RNA i lines were more susceptible to the pathogen. Metabolic analysis revealed that the production of a monoterpene ( S )‐limonene was increased and decreased in Os TPS 19 overexpression and RNA i lines, respectively, suggesting that Os TPS 19 functions as a limonene synthase in planta . This notion was further supported by in vitro enzyme assays with recombinant Os TPS 19, in which Os TPS 19 had both sesquiterpene activity and monoterpene synthase activity, with limonene as a major product. Furthermore, in a subcellular localization experiment, Os TPS 19 was localized in plastids. Os TPS 19 has a highly homologous paralog, Os TPS 20, which likely resulted from a recent gene duplication event. We found that the variation in Os TPS 19 and Os TPS 20 enzyme activities was determined by a single amino acid in the active site cavity. The expression of Os TPS 20 was not affected by M. oryzae infection. This indicates functional divergence of Os TPS 19 and Os TPS 20. Lastly, ( S )‐limonene inhibited the germination of M. oryzae spores in vitro . Os TPS 19 was determined to function as an ( S )‐limonene synthase in rice and plays a role in defence against M. oryzae, at least partly, by inhibiting spore germination.
ISSN:1467-7644
1467-7652
DOI:10.1111/pbi.12914