IDENTIFICATION OF PHYSIOLOGICAL AND GENETIC RESPONSES ASSOCIATED WITH TOMATO SPOTTED WILT VIRUS IN CULTIVATED PEANUTS

• Sponsoring Institution: Agricultural Research Service/USDA
• Project Status: TERMINATED
• Funding Source: USDA INHOUSE
• Reporting Frequency: Annual
• Accession No.: 0408291
• Project No.: 6604-13210-004-04R
• Project Start Date: Jan 1, 2004
• Project End Date: Dec 31, 2004

Project Director
ROWLAND D

Recipient Organization
AGRICULTURAL RESEARCH SERVICE
(N/A)
DAWSON,GA 31742

Performing Department
(N/A)

Non Technical Summary
(N/A)

Animal Health Component

(N/A)

Research Effort Categories

Basic

40%

Applied

60%

Developmental

0%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
203	1830	1020	30%
205	1830	1020	30%
206	1830	2000	20%
405	1830	2090	20%

Knowledge Area
405 - Drainage and Irrigation Systems and Facilities; 203 - Plant Biological Efficiency and Abiotic Stresses Affecting Plants; 205 - Plant Management Systems; 206 - Basic Plant Biology;

Subject Of Investigation
1830 - Peanut;

Field Of Science
1020 - Physiology; 2000 - Chemistry; 2090 - Statistics, econometrics, and biometrics;

Keywords

phorate

cultivars

tswv

thrips

peanut

physiology

Goals / Objectives
Tomato spotted wilt Tospovirus (TSWV) costs an estimated 100 million dollars annually to southeastern agricultural commodities including the peanut industry through reduction in yields. While it is known that several species of thrips are the primary vector for the spread of the virus, little is truly understood about its spread throughout a peanut plant and concominant plant physiological and genetic responses. Because of the seemingly random nature of TSWV infection, more information is needed about its spread through different tissues of the plant, the possible physiological mechanisms that impart resistance to the spread of infection, and the physiological effects of thrips insecticide control treatments. In general, the use of insecticides alone to control thrips vectors has been an ineffective means of suppressing TSWV, with the exception of the in-furrow application of the systemic insecticide phorate. Phorate has demonstrated consistent, low-level suppression of TSWV, but the mechanism of suppression is unknown. Becaue the level of thrips control obtained with phorate is not greater than that obtained with other insecticides, the mechanism of suppression is unlikely due to a decrease in vector population. We hypothesize that phorate may induce a defense response, most likely physiological, in the peanut plant that allows it to better resist TSWV. In previous work, differential display of mRNA was used to identify gene products that are regulated by phorate treatment and may be linked to physiological response mechanisms.

Project Methods
We propose to examine the progression of infection of TSWV in various peanut varieties and determine the effect of TSWV on peanut physiology and gene expression using both a field based and manipulative experiment. In the field based experiment, we propose to 1) quantify the physiological responses to TSWV infection, especially related to water use, in different peanut vearites through the growing season at different stages of TSWV infection, 2) examine the effect of pre-plant insecticide treatments on these physiologicaal responses, 3) correlate the expression of peanut defense response genes involved with increased resistance to TSWV with the above physiological responses, and 4) determine the impact of specific climatological factors on peanut plant growth and severity of TSWV. In the manipulative experiment, we propose to identify early response genes associated with resistance to TSWV via subtractive and suppression hybridization (SSH) using resistant and susceptible cultivars.

Progress 01/01/04 to 12/31/04

Outputs
4d Progress report. This report serves to document research conducted under a trust agreement with the Georgia Peanut Commission. Additional details of research can be found in the report for the parent CRIS 6604-13210-002-00D, Assessment of the Physiological Mechanisms Affecting Yield and Quality in Peanut Production. Research was completed which: 1) quantified the physiological responses to TSWV (tomato spotted wilt virus) infection, especially related to gas exchange, in different peanut varieties through the growing season at different stages of TSWV infection, 2) examined the effect of pre-plant insecticide treatments on these physiological responses, and 3) correlated the expression of peanut defense response genes involved with increased resistance to TSWV with the above physiological responses. Accomplishment of these objectives is critical to combating a disease that causes $100 million in annual commodity losses and $40 million annual losses to the peanut industry in Georgia alone. To accomplish these objectives, several currently utilized peanut varieties were grown under three insecticide treatments: phorate, aldicarb, and non-treated soils. The following traits were measured throughout the growing season: gas exchange including photosynthesis, water-use physiology, chlorophyll status, leaf nutrient levels, virus infection, and gene expression. This detailed knowledge of the progression of TSWV and its effect on physiological and genetic responses will improve production methods that increase the resistance of peanut to TSWV both through breeding and improvements in the management of insecticide treatments for TSWV.

Impacts
(N/A)

Publications

Progress 10/01/03 to 09/30/04

Outputs
4. What were the most significant accomplishments this past year? This report serves to document research conducted under a trust agreement with the National Peanut Board. Additional details of research can be found in the report for the parent CRIS 6604-13210-002-00D, Assessment of the Physiological Mechanisms Affecting Yield and Quality in Peanut Production. Research was completed which: 1) quantified the physiological responses to TSWV (tomato spotted wilt virus) infection, especially related to gas exchange, in different peanut varieties through the growing season at different stages of TSWV infection, 2) examined the effect of pre-plant insecticide treatments on these physiological responses, and 3) correlated the expression of peanut defense response genes involved with increased resistance to TSWV with the above physiological responses. Accomplishment of these objectives is critical to combating a disease that causes $100 million in annual commodity losses and $40 million annual losses to the peanut industry in Georgia alone. To accomplish these objectives, several currently utilized peanut varieties were grown under three insecticide treatments: phorate, aldicarb, and non-treated soils, and the following traits were measured throughout the growing season: gas exchange including photosynthesis, water-use physiology, chlorophyll status, leaf nutrient levels, virus infection, and gene expression. This detailed knowledge of the progression of TSWV and its effect on physiological and genetic responses will improve production methods that increase the resistance of peanut to TSWV both through breeding and improvements in the management of insecticide treatments for TSWV.

Impacts
(N/A)

Publications