CC-NBS-LRR-Type R Proteins for Rice Blast Commonly Interact with Specific WRKY Transcription Factors

Abstract

Rice blast resistance caused by Resistance (R) genes, most of which encode coiled-coil (CC), nucleotidebinding (NB), and leucine-rich-repeat (LRR) domains, is race-specific. Panicle blast 1 (Pb1) is a panicle blast resistance gene that confers a durable non-race-specific blast resistance to rice. Despite being non-R, Pb1 also encodes a CC-NB-LRR protein. Pb1 specifically interacts with rice WRKY45, a transcription factor (TF) in the rice salicylic acid signaling pathway, through its CC domain, and that this interaction is important for the blast resistance conferred by Pb1. Additionally, barley MLA10, an R protein for Blumeria graminis, specifically interacts with HvWRKY1/2. Here, we investigated whether the blast resistance between conferred by R genes and non-R Pb1 genes is mediated by their interaction with WRKY TFs. We performed targeted yeast two-hybrid and glutathione S-transferase (GST)-pull-down assays, which showed that all the five rice R proteins of the CC-NB-LRR type tested, Pi36, Pib, Pita, Pit, and Piz-t, interacted with WRKY45 and WRKY66 through their CC domains. However, elicitor-triggered immunity due to these R genes was not affected by the knockdown of these WRKY genes. The results suggest that R proteins can potentially transduce defense signals by interacting with WRKY TFs but the potentials are masked by HR-mediated elicitor-triggered immunity responses.

A Genome-Wide Association Study of Field Resistance to Magnaporthe Oryzae in Rice

“…Next, we identified 74 candidate genes in the LAFBR regions and obtained their annotation information (Additional file 3 : Table S3). None of them are homologous to any known NBS-type R gene family in the rice genome (Liu et al 2015 ; Liebranda et al 2013 ; Hu et al 2005 ) (Additional file 3 : Table S3). We classified those candidate genes into nine gene families based on the gene annotation information: 1) 20.3 % (15 of 74) belong to the receptor-like protein kinase gene family; 2) 16.2 % (12 of 74) are transcription factor genes; 3) 12.2 % (9 of 74) are ubiquitin-related genes; 4) 12.2 % (9 of 74) are phosphorylation-related genes; 5) 10.8 % (8 of 74) are DNA/ATP-binding genes; 6) 8.1 % (6 of 74) are oxidase/oxidoreductase genes; 7) 5.4 % (4 of 74) are heat shock protein genes; 8) 4.1 % (3 of 74) are LRR type genes; and 9) 10.8 % (8 of 74) are other defence related genes (Fig.…”

Structural and Functional Insights into WRKY3 and WRKY4 Transcription Factors to Unravel the WRKY–DNA (W-Box) Complex Interaction in Tomato (Solanum lycopersicum L.). A Computational Approach

“…The gene expression analysis following the inoculation with Botrytis cinerea through microarray revealed the differential expression of WRKY TFs within 18 h of pathogen infection (Windram et al, 2012 ). In one study, Liu et al ( 2016 ) reported the increased expression of WRKY6 gene in the Solanum pimpinellifolium cultivar L3708 after the plants found infection with Phytophthora infestans and Botrytis cinerea or get exposed to other abiotic stress. Similarly, the increased resistance against downy mildew pathogen was demonstrated in five transgenic broccoli lines over-expressing BoWRKY6 (Jiang et al, 2016 ).…”

“…The conserved motifs and slightly varied WRKY domain play crucial role in mediating complex functional protein-protein interaction observed between different WRKY members or those reported for WRKYs with other regulatory protein partners through both auto regulation or may involve cross regulatory mechanisms (Chi et al, 2013 ; Agarwal et al, 2014 ). The cross-regulatory pathway for their regulatory mechanism may involve several interacting proteins such as DNA binding proteins and other components including MAP kinases (Ishihama and Yoshioka, 2012 ), calmodulin (Park et al, 2005 ), VQ proteins (Chi et al, 2013 ), histone deacetylases (Glatt et al, 2011 ), E3 ubiquitin ligases (Miao and Zentgraf, 2010 ), and CC-NBS-LRR type R-proteins (Liu et al, 2016 ). The autoregulatory control mechanism could occur through negative feedback loop and direct binding of the pathogen associated molecular pattern (PAMP) induced WRKY genes and other expressed target genes.…”

Strategies for Breeding Durable Resistance to Rice Blast Using pi21

“…Pb1 transcript levels have increased during the development of Pb1-resistant varieties and effectively control panicle blast [58]. Pb1-mediated resistance seems to be mediated by a signaling pathway distinct from that involving typical NBS-LRR proteins [59].…”