Tomato Transcription Factors Pti4, Pti5, and Pti6 Activate Defense Responses When Expressed in Arabidopsis Plants - Respond to pathogen attack---- by activating multiple defense mechanisms to protect themselves from infection. - Recognition of specific pathogens and the activation of highly regulated signal transduction pathways. - A major target of these pathways is the cell nucleus, where signals lead to the transcriptional activation of a large array of defense genes - The products of these genes include pathogenesis-related (PR) proteins as well as enzymes involved in the biosynthesis of protective secondary metabolites. - Although the functions of many PR proteins remain unknown, some PR proteins, :: 1,3-glucanase (PR2) and chitinase (PR3), are hydrolytic enzymes that have been shown to degrade fungal cell walls and to inhibit fungal growth both in vivo and in vitro Several signaling molecules - Salicylic acid (SA),ethylene (ET), jasmonic acid (JA), - Defense response pathways - The SA-dependent defense signaling pathway :: PR1, PR2, and PR5. - The ET/JA-dependent signaling pathway(s) :: PR3, PR4, and PDF1.2. Ethylene (C2H4) :: , , , , , Salicylic acid :: Arum thermogenesis calorigenic substance . pathogenesis-related protein . ABA . . Jasmonic Acid :: . , ,tuber , , , . systemin , proteinase inhibitor Avirulent pathogenVirulent pathogen CPR5 NDR1 EDS1 PAD4 EDSs ROS HR ETJASA EIN2COI1 JAR1 NPR1 PDF1.2, Thi2.1 Resistance to P.parasitica ISR PR gene SAR Resistance to P.parasitica ? Abstract Pto(ser-thr protein kinase) binding transcription factor involved ethylene-response factor (ERF) family GCC-box binding SA, Ethylene response PR1,2 PR3,4 PDF1.2 Thi2.1 These results indicate that Pti4, Pti5, and Pti6 activate the expression of a wide array of PR genes and play important and distinct roles in plant defense. Pti4, Pti5, Pti6 Localized to the nucleus Figure 1. Nuclear Localization of Pti4/5/6. Figure 2. Transactivation of GCC BoxMediated Transcription by Pti4/5/6 Figure 3. Transactivation of the GAL4X9-GUS Reporter Gene by GAL4DB-Pti4/5/6 Fusion Proteins. Figure 4. Ectopic Expression of Pti4/5/6 in Arabidopsis and Triple-Response Assay of the Transgenic Plants. Figure 5. Overexpression of Pti4/5/6 in Arabidopsis Causes Constitutive Upregulation of PR Genes. Figure 6. Overexpression of Pti4/5/6 Sensitized the SA Signaling Pathway, and SA Suppressed the Expression of PDF1.2 Transcripts in thePti4-Overexpressing Line. Figure 7. Activation of PDF1.2 by the Overexpression of Pti4 Is Independent of the ET and JA Signaling Pathways. Figure 8. Expression of Pti4 in Arabidopsis Confers Increased Resistance to Erysiphe and Tolerance to Pseudomonas. Figure 9. Model for the Proposed Role of Pti4 and AtERFs in Mediating Cross-Talk between the SA and ET/JA Pathways.