Maize Homologs of Hydroxycinnamoyltransferase, a Key Enzyme in Lignin Biosynthesis, Bind the Nucleotide Binding Leucine-Rich Repeat Rp1 Proteins to Modulate the Defense Response

• Published in: Plant physiology (Bethesda) Vol. 169; no. 3; pp. 2230 - 2243
• Main Authors: Wang, Guan-Feng, He, Yijian, Strauch, Renee, Olukolu, Bode A., Nielsen, Dahlia, Li, Xu, Balint-Kurti, Peter J.
• Format: Journal Article
• Language: English
• Published: United States American Society of Plant Biologists 01.11.2015
• Subjects: Acyltransferases - genetics; Acyltransferases - metabolism; Biology; Biosynthesis; Carrier Proteins - genetics; Carrier Proteins - metabolism; Corn; Disease Resistance - immunology; Genes; Genome-Wide Association Study; Hematocrit; Lignin; Lignin - biosynthesis; Models, Biological; NLR Proteins - genetics; NLR Proteins - metabolism; Pathogens; Phenotype; Phenotypes; Phylogeny; Plant Diseases - immunology; Plant Leaves - enzymology; Plant Leaves - genetics; Plant Leaves - immunology; Plant Leaves - physiology; Plant Proteins - genetics; Plant Proteins - metabolism; Plants; Proteins; Proteins - genetics; Proteins - metabolism; Quantitative Trait Loci; Signal Transduction; SIGNALING AND RESPONSE; Zea mays - enzymology; Zea mays - genetics; Zea mays - immunology; Zea mays - physiology
• ISSN: 0032-0889; 1532-2548; 1532-2548
• DOI: 10.1104/pp.15.00703

In plants, most disease resistance genes encode nucleotide binding Leu-rich repeat (NLR) proteins that trigger a rapid localized cell death called a hypersensitive response (HR) upon pathogen recognition. The maize (Zea mays) NLR protein Rp1-D21 derives from an intragenic recombination between two NLRs, Rp1-D and Rp1-dp2, and confers an autoactive HR in the absence of pathogen infection. From a previous quantitative trait loci and genome-wide association study, we identified a single-nucleotide polymorphism locus highly associated with variation in the severity of Rp1-D21-induced HR. Two maize genes encoding hydroxycinnamoyltransferase (HCT; a key enzyme involved in lignin biosynthesis) homologs, termed HCT1806 and HCT4918, were adjacent to this single-nucleotide polymorphism. Here, we show that both HCT1806 and HCT4918 physically interact with and suppress the HR conferred by Rp1-D21 but not other autoactive NLRs when transiently coexpressed inNicotiana benthamiana. Other maize HCT homologs are unable to confer the same level of suppression on Rp1-D21-induced HR. The metabolic activity of HCT1806 and HCT4918 is unlikely to be necessary for their role in suppressing HR. We show that the lignin pathway is activated by Rp1-D21 at both the transcriptional and metabolic levels. We derive a model to explain the roles of HCT1806 and HCT4918 in Rp1-mediated disease resistance.