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Concurrent Session

Session: Concurrent Session: Extracellular & Intracellular non-self recognition & signaling (1)

Recognition of the bacterial type III effector RipAZ1, a suppressor of effector-triggered immunity, is conferred by paired NLRs carrying atypical integrated decoy domains in Solanum americanum

Monday, July 14, 2025
15:15 - 15:35  
Location: Room M+N

Ralstonia pseudosolanacearum is a devastating pathogen responsible for bacterial wilt disease in numerous plant hosts. However, only a limited number of bacterial wilt resistance genes have been identified so far. Solanum americanum, a close wild relative of economically important solanaceous crops such as tomato, possesses over 500 nucleotide-binding leucine-rich repeat receptors (NLRs), making it a promising candidate for discovering novel resistance genes. To identify bacterial wilt resistance genes, natural accessions of S. americanum were screened for resistance. The type III-secreted effector RipAZ1 from R. pseudosolanacearum has previously been shown to trigger accession-specific immune responses in S. americanum. Using bulk segregant analysis, we mapped the resistance gene locus to the upper arm of chromosome 5. Among 19 candidate NLRs, Resistance to R. solanacearum 1a (Rrs-amr1a) and Rrs-amr1b were found to be essential for RipAZ1 recognition. Interestingly, Rrs-amr1a exhibits an atypical domain architecture, featuring additional nucleotide-binding and leucine-rich repeat domains. Further analysis revealed that RipAZ1 can interfere with a key component of effector-triggered immunity (ETI) signaling. Taken together, the identification of these novel paired NLRs, which recognize the ETI suppressor RipAZ1, enhances our understanding of restricted taxonomic functionality and provides valuable insights for developing disease-resistant crops.