TaXa21, a LRR-rich receptor like kinase associated with TaWRKY76 and TaWRKY62, plays positive roles in wheat high-temperature seedling plant resistance to Puccinia striiformis f. sp. tritici

Authors: WANG, JIAHUI - Northwest Agricultural & Forestry University; WANG, JUNJUAN - Northwest Agricultural & Forestry University; SHANG, HONGSHENG - Northwest Agricultural & Forestry University; Chen, Xianming; XU, XIANGMING - East Malling Research; HU, XIAOPING - Northwest Agricultural & Forestry University

Submitted to: Molecular Plant-Microbe Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/18/2019
Publication Date: 6/25/2019
Citation: Wang, J., Wang, J., Shang, H., Chen, X., Xu, X., Hu, X. 2019. TaXa21, a LRR-rich receptor like kinase associated with TaWRKY76 and TaWRKY62, plays positive roles in wheat high-temperature seedling plant resistance to Puccinia striiformis f. sp. tritici. Molecular Plant-Microbe Interactions. https://doi.org/10.1094/MPMI-05-19-0137-R.
DOI: https://doi.org/10.1094/MPMI-05-19-0137-R

Interpretive Summary: Wheat stripe rust is one of most important diseases of wheat worldwide. High-temperature seedling-plant (HTSP) resistance of wheat to the pathogen is one specific type of host resistance, induced by high temperature. In the present study, a leucine rich repeat – RLK (LRR-RLK) gene, TaXa21 with a high homology with rice bacterial blight resistance gene Xa21, was cloned from wheat variety Xiaoyan 6. The expression of TaXa21 was up-regulated by the exposure to high-temeprature (20°C) for 24 hours at 8 days post inoculation, and was induced by ethylene (ET) and hydrogen peroxide. Knocking down TaXa21 using virus-induced gene silencing (VIGS) reduced stripe rust resistance. In addition, the expression level of TaCAT in the hydrogen peroxide pathway was induced, but reduced in the ET signal pathway in the high temperature-treated TaXa21-silenced plants. Transient expression of TaXa21 in tobacco leaves confirmed its subcellular localization in plasma membrane, consistent with the prediction from bioinformatic analysis. The transmembrane and kinase domain of TaXa21 can interact with wheat gene TaWRKY76 in the nucleus and cell membrane, different from the localization of Xa21 in rice. Interactions of TaXa21 with TaWRKY76 and TaWRKY62 (positively involved in HTSP resistance) were observed. Together, these results indicated that TaXa21 is a RLK associated with TaWRKY76 and TaWRKY62, and functions as a positive regulator of wheat resistance to stripe rust, enriching the understanding of plant resistance.

Technical Abstract: Puccinia striiformis f. sp. tritici (Pst) causes wheat stripe rust, one of most important diseases of wheat worldwide. High-temperature seedling plant (HTSP) resistance of wheat to Pst is one specific type of host resistance, induced by high temperature (HT). Receptor like kinases (RLKs) play key roles in regulating plant development and signalling networks, but there have been no reports on possible roles played by RLKs in the wheat HTSP to Pst. In the present study, a leucine rich repeat – RLK (LRR-RLK) gene, TaXa21 with a high homology with rice bacterial blight resistance gene Xa21, was cloned from wheat cultivar Xiaoyan 6 (XY 6). TaXa21 expression was up-regulated by the exposure to HT (20°C) for 24 hours at 8 days post Pst inoculation, and was induced by ethylene (ET) and H2O2. Knocking down TaXa21 using virus-induced gene silencing (VIGS) reduced HTSP resistance to Pst compared with the control plants. In addition, the expression level of TaCAT in the H2O2 pathway was induced and TaACO in the ET signal pathway was reduced in the HT-treated TaXa21-silenced plants. Transient expression of TaXa21 in tobacco leaves confirmed its subcellular localization in plasma membrane, consistent with the prediction from bioinformatic analysis. The transmembrane (TM) and kinase domain of TaXa21 can interact with TaWRKY76 in the nucleus and cell membrane, different from the localization of Xa21 in rice. Interactions of TaXa21 with TaWRKY76 and TaWRKY62 (positively involved in the HTSP resistance of XY 6) were observed. Together, these results indicated that TaXa21 is a RLK associated with TaWRKY76 and TaWRKY62, and functions as a positive regulator of wheat HTSP resistance to Pst. Furthermore, the host defense is mediated by the H2O2 and ET signal pathways.