Alternative Splicing of Rice WRKY62 and WRKY76 Transcription Factor Genes in Pathogen Defense1[OPEN]
Alternative splicing of two WRKY transcription factors plays a key role in pathogen sensitivity and alters pathogen-induced gene expression. The WRKY family of transcription factors ( TF s) functions as transcriptional activators or repressors in various signaling pathways. In this study, we discove...
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Veröffentlicht in: | Plant physiology (Bethesda) 2016-04, Vol.171 (2), p.1427-1442 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Alternative splicing of two WRKY transcription factors plays a key role in pathogen sensitivity and alters pathogen-induced gene expression.
The WRKY family of transcription factors (
TF
s) functions as transcriptional activators or repressors in various signaling pathways. In this study, we discovered that
OsWRKY62
and
OsWRKY76
, two genes of the WRKY IIa subfamily, undergo constitutive and inducible alternative splicing. The full-length OsWRKY62.1 and OsWRKY76.1 proteins formed homocomplexes and heterocomplexes, and the heterocomplex dominates in the nuclei when analyzed in
Nicotiana benthamiana
leaves. Transgenic overexpression of
OsWRKY62.1
and
OsWRKY76.1
in rice (
Oryza sativa
) enhanced plant susceptibility to the blast fungus
Magnaporthe oryzae
and the leaf blight bacterium
Xanthomonas oryzae
pv
oryzae
, whereas RNA interference and loss-of-function knockout plants exhibited elevated resistance. The dsOW62/76 and knockout lines of
OsWRKY62
and
OsWRKY76
also showed greatly increased expression of defense-related genes and the accumulation of phytoalexins. The ratio of full-length versus truncated transcripts changed in dsOW62/76 plants as well as in response to pathogen infection. The short alternative OsWRKY62.2 and OsWRKY76.2 isoforms could interact with each other and with full-length proteins. OsWRKY62.2 showed a reduced repressor activity in planta, and two sequence determinants required for the repressor activity were identified in the amino terminus of OsWRKY62.1. The amino termini of OsWRKY62 and OsWRKY76 splice variants also showed reduced binding to the canonical W box motif. These results not only enhance our understanding of the DNA-binding property, the repressor sequence motifs, and the negative feedback regulation of the IIa subfamily of WRKYs but also provide evidence for alternative splicing of WRKY
TF
s during the plant defense response. |
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ISSN: | 0032-0889 1532-2548 |
DOI: | 10.1104/pp.15.01921 |