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Plant Biotechnol J. 2016 Apr;14(4):1127-38. doi: 10.1111/pbi.12481. Epub 2015 Oct 8.

Development of disease-resistant rice by pathogen-responsive expression of WRKY45.

Author information

1
Disease Resistant Crops Research Unit, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan.
2
Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
3
Plant-Microbe Interaction Research Unit, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan.

Abstract

WRKY45 is an important transcription factor in the salicylic acid signalling pathway in rice that mediates chemical-induced resistance against multiple pathogens. Its constitutive overexpression confers extremely strong resistance against Magnaporthe oryzae and Xanthomonas oryzae pv. oryzae to rice, but has adverse effects on agronomic traits. Here, a new strategy to confer rice with strong disease resistance without any negative effects on agronomic traits was established by expressing WRKY45 under the control of pathogen-responsive promoters in combination with a translational enhancer derived from a 5'-untranslated region (UTR) of rice alcohol dehydrogenase (ADH). Rice promoters that responded to M. oryzae and X. oryzae pv. oryzae infections within 24 h were identified, and 2-kb upstream sequences from nine of them were isolated, fused to WRKY45 cDNA with or without the ADH 5'-UTR, and introduced into rice. Although pathogen-responsive promoters alone failed to confer effective disease resistance, the use of the ADH 5'-UTR in combination with them, in particular the PR1b and GST promoters, enhanced disease resistance. Field trials showed that overall, PR1b promoter-driven (with ADH 5'-UTR) lines performed the best and one had agronomic traits comparable to control untransformed rice. Thus, expressing WRKY45 under the control of the PR1b promoter with the ADH 5'-UTR is an excellent strategy to develop disease-resistant rice, and the line established could serve as a mother line for breeding disease-resistant rice.

KEYWORDS:

Magnaporthe oryzae; Oryza sativa; Xanthomonas oryzae; plant activator; salicylic acid; transcription factor

PMID:
26448265
DOI:
10.1111/pbi.12481
[Indexed for MEDLINE]
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