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 |
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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. |
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ISSN: | 1467-7644 1467-7652 |
DOI: | 10.1111/pbi.12914 |