NBS-LRR gene TaRPS2 is positively associated with the high-temperature seedling-plant resistance of wheat against Puccinia striiformis f. sp. tritici

Authors: HU, Y - Northwest A&f University; TAO, F - Northwest A&f University; SU, C - Northwest A&f University; ZHANG, Y - Northwest A&f University; LI, J - Northwest A&f University; WANG, J - Northwest A&f University; XU, X - Northwest A&f University; Chen, Xianming; SHANG, H - Northwest A&f University; HU, X - Northwest A&f University

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2020
Publication Date: 12/19/2020
Citation: Hu, Y.S., Tao, F., Su, C., Zhang, Y., Li, J., Wang, J.H., Xu, X.M., Chen, X., Shang, H.S., Hu, X.P. 2020. NBS-LRR gene TaRPS2 is positively associated with the high-temperature seedling-plant resistance of wheat against Puccinia striiformis f. sp. tritici. Phytopathology. https://doi.org/10.1094/PHYTO-03-20-0063-R.
DOI: https://doi.org/10.1094/PHYTO-03-20-0063-R

Interpretive Summary: Xiaoyan6 (XY6) is a wheat cultivar possessing race-non-specific high-temperature seedling-plant (HTSP) resistance against stripe rust. In previous studies, we identified a particular gene, TaRPS2, for its involvement in the HTSP resistance since its expression was highly up-regulated. To elucidate the role of TaRPS2 in the HTSP resistance, we cloned the full length of TaRPS2 from XY6, which is located on chromosome 2DL. The predicted amino acid sequence of TaRPS2 shares 98.69% similarity with an AetRPS2-like gene in wild wheat Aegilos tauschii, a typical nucleotide-binding site – leucine-rich repeat (NBS-LRR) protein, which plays crucial roles in plant resistance to fungal pathogens. The transcriptional expression level of TaRPS2 was rapidly up-regulated under the normal-high-normal temperature treatment. The expression level of TaRPS2 in wheat leaves was higher than that in the stems and roots. Two hours after H2O2 treatment or 0.5 h after exogenous hormone salicylic acid (SA) treatment, the expression level of TaRPS2 was increased by 2.66 times and 2.35 times, respectively. The subcellular localization of eGFP-TaRPS2 fusion protein was in the nucleus and plasma membranes. Overexpressing TaRPS2 in tobacco leaves showed programmed cell death. Virus-induced gene silencing of TaRPS2 decreased the level of HTSP resistance in XY6. Compared with the non-silenced leaves, the number of necrotic cells was reduced and the rust pustule number increased in the TaRPS2-silenced leaves. These results indicated that TaRPS2 positively regulates the HTSP resistance of XY6 against stripe rust and is related to the SA and H2O2 signaling pathways, improving the understanding the mechanisms of resistance.

Technical Abstract: Xiaoyan6 (XY6) is a wheat (Triticum aestivum L.) cultivar possessing race-non-specific high-temperature seedling-plant (HTSP) resistance against stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst). In previous studies, we identified a particular gene, TaRPS2, for its involvement in the HTSP resistance since its expression was highly up-regulated. To elucidate the role of TaRPS2 in the HTSP resistance, we cloned the full length of TaRPS2 from XY6, which is located on chromosome 2DL. The predicted amino acid sequence of TaRPS2 shares 98.69% similarity with AetRPS2-like of Aegilos tauschii, a typical nucleotide-binding site – leucine-rich repeat (NBS-LRR) protein, which plays crucial roles in plant resistance to fungal pathogens. The transcriptional expression level of TaRPS2 was rapidly up-regulated (16.13-fold 12 h post the temperature treatment) under the normal-high-normal temperature treatment. The expression level of TaRPS2 in wheat leaves was higher than that in the stems and roots. Two hours after H2O2 treatment or 0.5 h after exogenous hormone salicylic acid (SA) treatment, the expression level of TaRPS2 was increased by 2.66 times and 2.35 times, respectively. The subcellular localization of eGFP-TaRPS2 fusion protein was in the nucleus and plasma membranes. Overexpressing TaRPS2 in Nicotiana benthamiana showed programmed cell death. Virus-induced gene silencing (VIGS) of TaRPS2 decreased the level of HTSP resistance in XY6. Compared with the non-silenced leaves, the number of necrotic cells was reduced and the uredinium number increased in the TaRPS2-silenced leaves. These results indicated that TaRPS2 positively regulates the HTSP resistance of XY6 against Pst and is related to the SA and H2O2 signaling pathways.