Submitted to: International Plant Growth Promoting Rhizobacteria Workshop
Publication Type: Proceedings
Publication Acceptance Date: 10/1/1997
Publication Date: N/A
Citation: Interpretive Summary: There is tremendous public support for reducing the use of chemical pesticides in agriculture, so we are investigating the use of bacteria to manage plant diseases that are presently controlled by fungicides or bactericides. Unlike chemical pesticides, biological control agents are living entities that respond to changes in the environment. The challenge we face is to understand the ways that the environment alters populations and activities of biological control agents, with the goal of developing biologically-based pest management that can be used reliably to manage agricultural problems, which occur under diverse environmental conditions. We are using techniques from molecular biology to learn about the way that biological control agents respond to the environment how these responses alter their success in controlling plant diseases. These techniques are described and ways in which we can make biological control more reliable are discussed.
Technical Abstract: Certain strains of rhizobacteria suppress plant pathogenic bacteria and fungi in the rhizosphere through processes of resource competition or antibiosis. These processes are not likely to occur uniformly in time or space; instead, they undoubtedly take place only in those microhabitats where environmental factors favor their occurrence, and during periods in the bacterial life cycle when genes involved in resource utilization or antibiotic production are expressed. The recent literature provides numerous and compelling examples that resource competition and antibiosis occur among microorganisms coinhabiting the rhizosphere, but their importance in determining the outcome of microbial interactions is neither absolute nor entirely predictable. Consequently, an understanding of factors influencing the processes of resource competition and antibiosis has become a subject of active research during the past several years. Tools are now available to assess the chemical nature of habitats that bacteria occupy in the rhizosphere, to determine if resource availability to microorganisms is influenced by their coinhabitants in the rhizosphere, and to evaluate the in situ expression of genes involved in antibiotic biosynthesis or resource utilization by bacteria inhabiting the rhizosphere. Utilizing such tools, investigators have gained further appreciation for the diverse interactions that occur between bacterial antagonists and target plant pathogens in the rhizosphere.