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Plant Mol Biol. 2014 Sep;86(1-2):171-83. doi: 10.1007/s11103-014-0221-x. Epub 2014 Jul 18.

WRKY45-dependent priming of diterpenoid phytoalexin biosynthesis in rice and the role of cytokinin in triggering the reaction.

Author information

1
Disease Resistant Crops Research Unit, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki, 305-8602, Japan.

Abstract

Plant activators such as benzothiadiazole (BTH) protect plants against diseases by priming the salicylic acid (SA) signaling pathway. In rice, the transcription factor WRKY45 plays a central role in this process. To investigate the mechanism involved in defense-priming by BTH and the role of WRKY45 in this process, we analyzed the transcripts of biosynthetic genes for diterpenoid phytoalexins (DPs) during the rice-Magnaporthe oryzae interaction. The DP biosynthetic genes were barely upregulated in BTH-treated rice plants, but were induced rapidly after M. oryzae infection in a WRKY45-dependent manner. These results indicate that the DP biosynthetic genes were primed by BTH through WRKY45. Rapid induction of the DP biosynthetic genes was also observed after M. oryzae infection to WRKY45-overexpressing (WRKY45-ox) plants. The changes in gene transcription resulted in accumulation of DPs in WRKY45-ox and BTH-pretreated rice after M. oryzae infection. Previously, we reported that cytokinins (CKs), especially isopentenyladenines, accumulated in M. oryzae-infected rice. Here, we show that DP biosynthetic genes are regulated by the SA/CK synergism in a WRKY45-dependent manner. Together, we propose that CK plays a role in mediating the signal of M. oryzae infection to trigger the induction of DP biosynthetic genes in BTH-primed plants.

PMID:
25033935
PMCID:
PMC4133022
DOI:
10.1007/s11103-014-0221-x
[Indexed for MEDLINE]
Free PMC Article

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