SYSTEMIC ACQUIRED RESISTANCE

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 0208314
• Project Start Date: Jul 1, 2006
• Project End Date: Oct 10, 2007
• Program Code: [(N/A)]- (N/A)

Recipient Organization
KANSAS STATE UNIV
(N/A)
MANHATTAN,KS 66506

Performing Department
BIOLOGY

Non Technical Summary
Worldwide crop losses to disease exceed $ 100 billion per annum. The increased dependence on toxic chemicals to protect plants is endangering our environment and health. Alternative safer and cost-effective strategies are urgently needed to protect plants against diseases. Systemic acquired resistance (SAR) provides an excellent target for enhancing disease resistance in plants. SAR is activated in plants previously exposed to a necrogenic pathogen. SAR confers resistance against a broad-spectrum of pathogens. The translocation of a phloem-mobile signal is required for SAR. This study will characterize the role of lipid in the SAR and further study the involvement of the Arabidopsis SFD1 protein in SAR. A combination of molecular, biochemical and genetic approaches will be pursued. The identification of the phloem mobile factor in SAR will allow for the targeting of this factor for either inducing defense mechanisms in plants or for engineering disease resistance in plants.

Animal Health Component

(N/A)

Research Effort Categories

Basic

100%

Applied

(N/A)

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
201	2499	1040	50%
212	2499	1040	50%

Knowledge Area
212 - Pathogens and Nematodes Affecting Plants; 201 - Plant Genome, Genetics, and Genetic Mechanisms;

Subject Of Investigation
2499 - Plant research, general;

Field Of Science
1040 - Molecular biology;

Keywords

defense signaling

plant defense

induced resistance

phloem

broad-spectrum resistance;

Goals / Objectives
Systemic acquired resistance (SAR) is an inducible defense mechanism that confers enhanced resistance against a broad-spectrum of pathogens. The activation of SAR requires prior exposure to pathogen, which results in the translocation of a factor through the phloem. This phloem-mobile factor primes plant defenses to respond faster to subsequent attack by pathogens. Lipids have an important role in the synthesis and/or translocation of this phloem mobile factor in SAR. The aims of this project are to identify this phloem mobile factor in SAR and to assess the role of the SFD1 protein in the activation of SAR. These studies will be performed in Arabidopsis thaliana. The specific objectives are: Objective 1: A combination of biochemical, molecular and metabolomic approaches will be undertaken to identify the phloem-mobile factor in SAR. Objective 2: Molecular and biochemical approaches will be undertaken to understand the role of lipid in SAR. Objective 3: Molecular, biochemical and genetic approaches will be undertaken to characterize the role of SFD1 in SAR.

Project Methods
1. We will compare changes in lipid composition in wild type and SAR-deficient Arabidopsis plants before and after inoculation with pathogen. ESI-MS/MS and GC-MS will be used for monitoring lipid compositional changes. 2. A biological assay will be used to characterize petiole exudates from wild type and SAR-deficient mutants for the presence of the SAR-inducing factor. 3. The intracellular localization of SFD1, a dihydroxyacetone phosphate (DHAP) reductase enzyme that is required for the activation of SAR, will be studied by a combination of biochemical and molecular approaches. 4. Biochemical and molecular approaches will be pursued to determine if the DHAP reductase activity of SFD1 is required for SAR

Progress 01/01/07 to 12/31/07

Outputs
OUTPUTS: Systemic acquired resistance (SAR) can be activated in the distal organs of a plant that has been previously inoculated with an avirulent pathogen. A SAR inducing activity was present in petiole exudates from avirulent pathogen inoculated Arabidopsis leaves. This SAR inducing activity from Arabidopsis leaves was effective in promoting disease resistance when applied to Arabidopsis, tomato and wheat. Genetic studies in Arabidopsis thaliana have indicated that plant galactolipids have an important role in the generation/accumulation of a systemic acquired resistance (SAR)-inducing factor in petiole exudates of avirulent pathogen inoculated plants. Genetic and biochemical evidence indicates that jasmonic acid, which is also derived from galactolipids, is not a component of this SAR activating factor that is present in petiole exudates. PARTICIPANTS: Ratnesh Chaturvedi (post doctoral associate); Kartikeya Krothapalli (graduate student) TARGET AUDIENCES: Scientific community, Plant Protection industries, Biotechnology industry, Integrated Pest Management strategists and Environmentalists. PROJECT MODIFICATIONS: None.

Impacts
The identity of the SAR inducing factor will promote the development of improved strategies for protecting plants against a broad-spectrum of pathogens, thereby improving agricultural productivity and quality.

Publications

• Shah, J., and Chaturvedi, R. 2008. Lipid signals in plant-pathogen interaction. Annu. Plant Rev. In press.
• Chaturvedi, R., Krothapalli, K., Makandar, R., Nandi, A., Sparks, A., Roth, M., Welti, R. and Shah, J. 2008. Plastid omega-3 desaturase-dependent accumulation of a systemic acquired resistance inducing activity in petiole exudates of Arabidopsis thaliana is independent of jasmonic acid. Plant J. In press.

Progress 07/01/06 to 10/10/07

Outputs
OUTPUTS: Systemic acquired resistance (SAR) can be activated in the distal organs of a plant that has been previously inoculated with an avirulent pathogen. A SAR inducing activity was present in petiole exudates from avirulent pathogen inoculated Arabidopsis leaves. This SAR inducing activity from Arabidopsis leaves was effective in promoting disease resistance when applied to Arabidopsis, tomato and wheat. Genetic studies in Arabidopsis thaliana have indicated that plant galactolipids have an important role in the generation/accumulation of a systemic acquired resistance (SAR)-inducing factor in petiole exudates of avirulent pathogen inoculated plants. Genetic and biochemical evidence indicates that jasmonic acid, which is also derived from galactolipids, is not a component of this SAR activating factor that is present in petiole exudates. PARTICIPANTS: Ratnesh Chaturvedi (post doctoral associate); Kartikeya Krothapalli (graduate student) TARGET AUDIENCES: Scientific community, Plant Protection industries, Biotechnology industry, Integrated Pest Management strategists and Environmentalists. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The identity of the SAR inducing factor will promote the development of improved strategies for protecting plants against a broad-spectrum of pathogens, thereby improving agricultural productivity and quality.

Publications

• Shah, J., and Chaturvedi, R. 2008. Lipid signals in plant-pathogen interaction. Annu. Plant Rev. In press.
• Chaturvedi, R., Krothapalli, K., Makandar, R., Nandi, A., Sparks, A., Roth, M., Welti, R. and Shah, J. 2008. Plastid omega-3 desaturase-dependent accumulation of a systemic acquired resistance inducing activity in petiole exudates of Arabidopsis thaliana is independent of jasmonic acid. Plant J. In press.