OsWRKY03, a rice transcriptional activator that functions in defense signaling pathway upstream of OsNPR1

Abstract

WRKY family proteins are a class of plant specific transcription factors that involve in many stress response pathways. It has been shown that one Arabidopsis WRKY protein, AtWRKY29/22, is activated by MAP kinase signaling cascade and confers resistance to both bacterial and fungal pathogens. However, little is known about the biological roles of WRKY proteins in rice. In this study, we investigated the expression patterns of rice AtWRKY29/22 homolog, OsWRKY03, under different conditions, and also its possible role involved in plant defense. Our results showed that OsWRKY03 was up-regulated by several defense signaling molecules or different treatments. Further analysis revealed that the expression of OsWRKY03 was light dependent. Transcriptional activation activity of OsWRKY03 was also demonstrated by yeast functional assay. Transient expression of OsWRKY03-GFP fusion protein in onion epidermis cells showed that OsWRKY03 was a nuclear localized protein. OsNPR1 as well as several other pathogenesis-related genes, such as OsPR1b, phenylalanine ammonia-lyase (ZB8) and peroxidase (POX22.3), were induced in OsWRKY03-overexpressing transgenic plants. These results indicated that OsWRKY03 is located upstream of OsNPR1 as a transcriptional activator in salicylic acid (SA)-dependent or jasmonic acid (JA)-dependent defense signaling cascades.

The Role of WRKY Transcription Factors in Plant Immunity

“…Similarly, OsWRKY53 overexpressor lines are more resistant to M. grisea and may act as a positive regulator of basal defense (Chujo et al, 2007). Expression of OsWRKY03 and OsWRKY71 is strongly induced by pathogen-mimicking stimuli, and these genes function upstream of OsNH1 (the rice ortholog of NPR1) in defense signaling (Liu et al, 2005. In the case of OsWRKY71, overexpressor lines display enhanced resistance to virulent Xoo .…”

HDT701, a Histone H4 Deacetylase, Negatively Regulates Plant Innate Immunity by Modulating Histone H4 Acetylation of Defense-Related Genes in Rice

“…In addition, the MAPK6-mediated cascade is activated by the RAC1 defensome complex to transduce PIT-mediated immunity (Lieberherr et al, 2005;Kawano et al, 2010). Similarly, the WRKY transcription factor family has been extensively studied for its role in the rice defense response (Liu et al, 2005;Liu et al, 2007;Qiu et al, 2007;Shimono et al, 2007;Chujo et al, 2008;Peng et al, 2008;Tao et al, 2009). Overexpression of WRKY53 induced after chitin treatment in cultured rice cells (Chujo et al, 2007) and in rice plants leads to enhanced resistance to M. oryzae, indicating its positive role in basal defense (Chujo et al, 2009).…”

Rice DENSE AND ERECT PANICLE 2 is essential for determining panicle outgrowth and elongation

“…The fusion construct and control were transformed into onion epidermis cells by particle bombardment using PDS-1000/He (BIO-RAD) [38]. This construct was also introduced into Agrobacterium tumefaciens GV3101 and then infiltrated into the leaves of 3-week-old Nicotiana benthamiana plants [39,40].…”