Development of disease‐resistant rice by optimized expression of WRKY45. Issue 6 (9th December 2014)

• Record Type: Journal Article
• Authors: Goto, Shingo; Sasakura‐Shimoda, Fuyuko; Suetsugu, Mai; Selvaraj, Michael Gomez; Hayashi, Nagao; Yamazaki, Muneo; Ishitani, Manabu; Shimono, Masaki; Sugano, Shoji; Matsushita, Akane; Tanabata, Takanari; Takatsuji, Hiroshi
• Is Part Of: Plant biotechnology journal. Volume 13:Issue 6(2015:Aug.)
• Page Start: 753
• Page End: 765
• Publication Date: 2014-12-09
• Subjects: Plant biotechnology -- Periodicals; Plant genetic engineering -- Periodicals; 630.272
• DOI: 10.1111/pbi.12303
• Languages: English
• ISSNs: 1467-7644

Abstract

<abstract abstract-type="main" id="pbi12303-abs-0001"> <title>Summary</title> <p>The rice transcription factor WRKY45 plays a central role in the salicylic acid signalling pathway and mediates chemical‐induced resistance to multiple pathogens, including <italic>Magnaporthe oryzae</italic> and <italic>Xanthomonas oryzae</italic> pv. <italic>oryzae</italic>. Previously, we reported that rice transformants overexpressing <italic>WRKY45</italic> driven by the maize <italic>ubiquitin</italic> promoter were strongly resistant to both pathogens; however, their growth and yield were negatively affected because of the trade‐off between the two conflicting traits. Also, some unknown environmental factor(s) exacerbated this problem. Here, we report the development of transgenic rice lines resistant to both pathogens and with agronomic traits almost comparable to those of wild‐type rice. This was achieved by optimizing the promoter driving <italic>WRKY45</italic> expression. We isolated 16 constitutive promoters from rice genomic DNA and tested their ability to drive <italic>WRKY45</italic> expression. Comparisons among different transformant lines showed that, overall, the strength of <italic>WRKY45</italic> expression was positively correlated with disease resistance and negatively correlated with agronomic traits. We conducted field trials to evaluate the growth of transgenic and control lines. The agronomic traits of two lines expressing <italic>WRKY45</italic> driven by the <italic>OsUbi7</italic> promoter (P<sub><italic>O</italic></sub><sub><italic>sUbi7</italic></sub> lines) were nearly comparable to those of untransformed rice, and both lines were pathogen resistant. Interestingly, excessive <italic>WRKY45</italic> expression rendered rice plants sensitive to low temperature and salinity, and stress sensitivity was correlated with the induction of defence genes by these stresses. These negative effects were barely observed in the P<sub><italic>O</italic></sub><sub><italic>sUbi7</italic></sub> lines. Moreover, their patterns of defence gene expression were similar to those in plants primed by chemical defence inducers.</p> </abstract>