Defended to the Nines 25 Years of Resistance Gene Cloning Identifies Nine Mechanisms for R Protein Function

• Published in: The Plant cell Vol. 30; no. 2; pp. 285 - 299
• Main Authors: Kourelis, Jiorgos, van der Hoorn, Renier A.L.
• Format: Journal Article
• Language: English
• Published: England American Society of Plant Biologists 01.02.2018
• Subjects: Cell surface; Cloning; Cloning, Molecular; Corn; Disease resistance; Disease Resistance - genetics; Genes; Immunity; Intracellular; Kinases; Leucine; Molecular modelling; Pathogens; Perception; Plant Diseases - immunology; Plant Proteins - genetics; Plants - genetics; Plants - immunology; Proteins; R protein; Receptors; REVIEW; Transcription activation; Zea mays; Zea mays - genetics; Zea mays - immunology
• ISSN: 1040-4651; 1532-298X
• DOI: 10.1105/tpc.17.00579

Plants have many, highly variable resistance (R) gene loci, which provide resistance to a variety of pathogens. The first R gene to be cloned, maize (Zea mays) Hm1, was published over 25 years ago, and since then, many different R genes have been identified and isolated. The encoded proteins have provided clues to the diverse molecular mechanisms underlying immunity. Here, we present a meta-analysis of 314 cloned R genes. The majority of R genes encode cell surface or intracellular receptors, and we distinguish nine molecular mechanisms by which R proteins can elevate or trigger disease resistance: direct (1) or indirect (2) perception of pathogen-derived molecules on the cell surface by receptor-like proteins and receptor-like kinases; direct (3) or indirect (4) intracellular detection of pathogen-derived molecules by nucleotide binding, leucine-rich repeat receptors, or detection through integrated domains (5); perception of transcription activator-like effectors through activation of executor genes (6); and active (7), passive (8), or host reprogramming-mediated (9) loss of susceptibility. Although the molecular mechanisms underlying the functions of R genes are only understood for a small proportion of known R genes, a clearer understanding of mechanisms is emerging and will be crucial for rational engineering and deployment of novel R genes.