Research Plant Pathologist
Dr. C. Jacyn Baker
Research Plant Pathologist
USDA-ARS-PSI-MPPL
bakerc@ba.ars.usda.gov
Phone: 301-504-5617
The overall goal of this project is to elucidate mechanisms that are pivotal to the plant/pathogen interaction with the intent that this knowledge will either help identify new strategies of disease control or aid in improving current control strategies by providing increased understanding.
In recent years it has become clear that oxidative metabolism affects and impacts various facets of life in both animals and plants and even more so during times of disease.
The field of oxidative metabolism is still in its infancy and not well defined but can be viewed as a collection of reactions in which electrons are either lost or gained (including redox reactions, light reactions, electron transport, and reactive oxygen reactions) and, although not necessarily part of the same biochemical pathway, they influence each other by their effect on the redox environment (which governs how readily electrons are exchanged).
There are reports of involvement in:
- Early signaling for both host and pathogen recognition responses
- Direct cellular damage to both host (leading to resistance in hypersensitive interactions) and pathogen
- Fortification of plant tissue through oxidative cross linking and lignification
- Induced resistance triggering physiological changes in favor of plant defense upon subsequent pathogen attack
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.
Plant Bacterial Recognition
We are interested in the earliest response mechanisms of the plant after contact and recognition of a pathogen has occurred. Active oxygen production is one of these mechanisms that occur within the first few hours. These initial response mechanisms are critical to determining whether the outcome of the interaction will be resistance or susceptibility.
Plant Stress
A chronological summary of events in plant pathogenesis that involve AO metabolism.
- Stage I encompasses signaling and the earliest events including plant/pathogen recognition and the initial phases of AO production and the respiratory burst. Active oxygen production continues throughout pathogenesis and may even increase in later stages, however, it is scavenged and may not accumulate to the levels observed during Stage I.
- Stage II includes AO generated from the secondary defense responses initiated by stage I including lignification and AO from increased metabolism.
- Stage III is comprised of the senescent or degradative processes, such as photooxidation and membrane lipoxidation, leading to tissue necrosis during a HR response or the development of symptoms in compatible interactions.
