Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 9, 2005
Publication Date: July 7, 2005
Citation: Baker, C.J., Whitaker, B.D., Mock, N.M., Rice, C., Deahl, K.L., Roberts, D.P., Ueng, P.P., Averyanov, A.A. 2005. Differential induction of extracellular bioactive phenolics that are redox sensitive. Physiological and Molecular Plant Pathology. 66:90-98.
Interpretive Summary: The goal of this work was to gain new insight into how plants and pathogens interact so that we can eventually develop new ways to improve crop resistance to disease. Here we report the identity of several chemicals that have the ability to regulate the plant/pathogen interaction; that is, we think these chemicals play an important role in determining whether the plants will be resistant or become diseased. These chemicals were produced by plant cells soon after they were inoculated with pathogens. We demonstrated that the exact type and amount of these chemicals depended on many different factors. By being aware of and being able to quantify these chemicals, which act as 'antioxidants' in plants, we will improve our understanding of how plants and pathogens interact and we can attempt to improve plant disease resistance. This work will benefit ARS and scientists by providing new knowledge about plant/pathogen interactions and help further investigations leading to improved crop disease resistance.
This study focuses on the transient and complex nature of extracellular phenolics during the initial stages of plant/pathogen interactions. Using suspension cells of Solanum tuberosum and Nicotiana tobaccum, the accumulation of phenolics in the extracellular suspension was monitored after addition of bacterial pathogens or pathogen-related products. Initially the focus was on the antioxidative effects of these phenolics and how they would affect the oxidative burst associated with resistant interactions. However, after identifying several of the phenolics as having bioactive properties, such as acetosyringone known for inducing the vir genes of Agrobacterium, we decided to further identify these compounds and the factors that affect their transient appearance. Recent studies have been demonstrating that the beneficial effects of plant phenolics on animal physiology, such as anti-depression, anti-tumor formation, and cardio-health are the result of specific molecular recognition mechanisms rather than antioxidative properties that are more often cited. Here we report the accumulation of several phenolics that have been demonstrated to be bioactive in other studies. We demonstrate that the qualitative and quantitative makeup of these phenolics is sensitive to the redox status, but also cell concentration, bacterial or elicitor concentration and plant cell age. This study provides the basis for in-depth investigation of specific phenolics on the host/pathogen interaction.