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) :: 줄기와 뿌리의 생장과 분화, 잎과 과실의 탈리 현상, 일부 식물에서 꽃눈의 유도, 개화, 꽃과 잎의 노쇠, 과실의 성숙을 촉진함 Salicylic acid :: Arum 의 꽃에서 thermogenesis 를 일으키는 calorigenic substance 이다. 보 다 일반적인 역할은 pathogenesis-related protein 의 합성을 유도하여 병원체 에 대한 저항을 나타내는 것이다. 또한 꽃의 개화기간을 연장시키고 에틸 렌 합성과 종자 발아를 저해하며 상처에 따른 반응을 차단하고 ABA 의 효과 를 상쇄한다. 내재적 역할이 있는지는 알려지지 않았다. Jasmonic Acid :: 생장이나 종자 발아를 저해한다. 또한 노화, 탈리,tuber 형성, 과실성숙, 색소 형성, 덩굴손의 꼬임을 촉진한다. 중요한 역할중의 하는 식물체의 방어인데 펩티드의 일종인 systemin 에 의해 유도되는 방어회로의 중간체로서, proteinase inhibitor 의 합성을 유도 하여 곤충의 섭식을 방해한다

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 Box–Mediated 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.