Two MAPK cascades, NPR1, and TGA transcription factors play a role in Pto‐mediated disease resistance in tomato

• Published in: The Plant journal : for cell and molecular biology 2003-12, Vol.36 (6), p.905-917
• Main Authors: Ekengren, Sophia K., Liu, Yule, Schiff, Michael, Dinesh‐Kumar, S. P., Martin, Gregory B.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; AvrPto protein; AvrPtoB protein; Base Sequence; Biological and medical sciences; DNA Primers; Fundamental and applied biological sciences. Psychology; Gene Silencing; Genetics and breeding of economic plants; Immunity, Innate - genetics; Lycopersicon esculentum; MAP Kinase Signaling System - physiology; Molecular Sequence Data; Pest resistance; Plant Diseases - microbiology; plant immunity; Plant pathogens; Plant Proteins - genetics; Plant Proteins - metabolism; Protein-Serine-Threonine Kinases - metabolism; Pseudomonas syringae; Pseudomonas syringae - pathogenicity; Pto kinase; TGA1a protein; TGA2.2 protein; Transcription Factors - genetics; Transcription Factors - metabolism; Varietal selection. Specialized plant breeding, plant breeding aims
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1046/j.1365-313X.2003.01944.x

Summary The tomato Pto kinase confers resistance to the causative agent of bacterial speck disease, Pseudomonas syringae pv. tomato, by recognizing the pathogen effector proteins AvrPto or AvrPtoB. Pto‐mediated resistance requires multiple signal transduction pathways and has been shown to activate many defense responses including an oxidative burst, rapid changes in the expression of over 400 genes, and localized cell death. We have tested the role in Pto‐mediated resistance in tomato of a set of 21 genes from other species known to be involved in defense‐related signaling. Expression of each gene was suppressed by virus‐induced gene silencing (VIGS) and the effect on disease symptoms and bacterial growth during the tomato–Pseudomonas incompatible interaction was determined. We found that Pto‐mediated resistance was compromised by silencing of genes encoding two mitogen‐activated protein (MAP) kinase kinases, MEK1 and MEK2, two MAP kinases, NTF6 and wound‐induced protein kinase (WIPK), a key regulator of systemic acquired resistance (SAR), NPR1, and two transcription factors, TGA1a and TGA2.2. A lesser impact on Pto‐mediated resistance was observed in plants silenced for RAR1 and COI1. The identification of nine genes that play a role in resistance to bacterial speck disease both advances our knowledge of Pto signal transduction and demonstrates the conservation of many defense signaling components among diverse plant species.