Signal transduction during activation of plant defenses against microbial attack
Abstract
Plants resist infections by secreting a certain number of substances after recognizing the presence of the pathogen. One of the earliest known defense responses is the production of $\rm H\sb2O\sb2.$ Because of its early appearance within the plant defense strategy, I decided to investigate its possible regulatory function on the expression of later responses like phytoalexin generation. However, I failed to find a causal relationship between the two events and turned my attention upstream of $\rm H\sb2O\sb2$ production. Due to its inherent cytotoxicity, the rapid generation of large quantities of $\rm H\sb2O\sb2$ by plant cells after recognition of a pathogen has been suggested to be under tight control. In order to study the intracellular mechanisms responsible for the control of the infection-induced oxidative burst, I purified one of its inducers, an oligogalacturonide elicitor, and characterized the kinetics and intensities of the oxidative bursts it initiates. In the same study, I also demonstrated that the elicitor-induced oxidative burst exhibits homologous and heterologous desensitization processes. Since the existence of such processes strongly suggests that the plant oxidative burst is controlled by intracellular second messengers, I set out to search for these intracellular elements. Two of these elements have since been characterized: (i) GTP-binding proteins, and (ii) polyphosphoinositide production.
Degree
Ph.D.
Advisors
Low, Purdue University.
Subject Area
Biochemistry|Plant pathology
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