Transcript Tomato Transcription Factors Pti4, Pti5, and Pti6 Activate

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
:: Arum의 꽃에서 thermogenesis를 일으키는 calorigenic substance이다.
보
다 일반적인 역할은 pathogenesis-related protein의 합성을 유도하여 병원체
에 대한 저항을 나타내는 것이다. 또한 꽃의 개화기간을 연장시키고 에틸
렌 합성과 종자 발아를 저해하며 상처에 따른 반응을 차단하고 ABA의 효과
를 상쇄한다. 내재적 역할이 있는지는 알려지지 않았다.
• Jasmonic Acid
:: 생장이나 종자 발아를 저해한다.또한 노화,탈리,tuber형성,과실성숙,색소 형성,
덩굴손의 꼬임을 촉진한다. 중요한 역할중의 하는 식물체의 방어인데 펩티드의
일종인 systemin에 의해 유도되는 방어회로의 중간체로서, proteinase inhibitor
의 합성을 유도 하여 곤충의 섭식을 방해한다
Avirulent pathogen
CPR5
NDR1
EDS1
Virulent pathogen
PAD4
EDSs
ROS
HR
ET
EIN2
JA
COI1
?
JAR1
PDF1.2, Thi2.1 ISR
Resistance to
P.parasitica
SA
NPR1
PR gene
SAR
Resistance to
P.parasitica
Abstract
Pti4, Pti5, Pti6
• Pto(ser-thr protein kinase) binding transcription factor
• involved ethylene-response factor (ERF) family
• Localized to the nucleus
• 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.
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.