Project Number: 1275-22000-195-00
Project Type: Appropriated

Start Date: Dec 04, 2002
End Date: Oct 31, 2007

Objective:
The goal of this project is to elucidate recognition mechanisms in the early phases of plant/pathogen interactions for the purpose of either revealing new opportunities for disease control or improving current control measures through increased understanding of these mechanisms. This study focuses on the role of oxidative metabolism, i.e. the production and regulation of prooxidants and antioxidants, in the earliest phases of the plant/pathogen interaction. This project specifically addresses the role/effect of extracellular or apoplastic antioxidants on the early events of the host/pathogen interaction. Objective 1: Determine the role/effect of plant apoplastic antioxidants in susceptibility or resistance during the early events in plant/bacterial interactions. Objective 2: Describe the role of prooxidants and antioxidants in the apoplast-infection droplet microenvironment in preventing successful penetration of the host by fungal spores.

Approach:
For bacterial pathogens, the first interaction with the plant generally occurs in the apoplast once the inoculum is absorbed into the tissue; for fungal pathogens the first interaction is often on the plant epidermis where, in many interactions, the apoplast interacts with the infection droplet. In this microenvironment a complex series of exchanges occurs between the host and pathogen affecting the oxidative balance - with prooxidants generally favoring the host (often causing localized cell death) and antioxidants favoring the pathogen. First we will use a bacteria/cell suspension model system, which mimics in planta recognition of Pseudomonas syringae by soybean, potato and tobacco, and is highly manipulable. Techniques and information gained from this system will be applied to examine the influence of the apoplast/infection-droplet microenvironment on spore germination of Magnaporthe grisea on rice leaves. A new noninvasive technique will allow quantification of the total oxidative burst as well as extracellular antioxidants. In addition to revealing the kinetics and key constituents of oxidative metabolism in the apoplast, we expect to gain quantitative and determinative information regarding its influence on bacterial and fungal interactions, apoplast redox status and cellular prooxidant-tolerance mechanisms. BSL-1, Recertified 8/2/02

Project Team

Baker, Con

Project Annual Reports

FY 2003