Chemical Ecology of Plant-Microbe-Insect Interactions — Feb 25, 2014, IISc, Bangalore
February 25, 2014
February 25, 2014
16:00 to 18:00
CES Seminar Hall,
Centre for Ecological Sciences, Indian Institute of Science, presents a talk:
Title: The Chemical Ecology of Plant-Microbe-Insect Interactions
Speaker: Radhika Venkatesan, RIKEN Special Postdoctoral Fellow, Plant Productivity Systems Research Group, Centre for Sustainable Resource Science, RIKEN Yokohama Institute, Japan
Abstract: Chemical ecology is the study of chemical interactions between organisms. Plants are central in most community networks and have evolved complex defensive strategies against herbivores and pathogens. In the first part of the presentation, plant pathogen interactions will be highlighted focusing on the infection mechanism of Rhodococcus fascians. This actinomycete invokes shooty malformations called leafy galls in many plant species by interfering with plant hormonal balance. The virulence determinant is located on a linear plasmid consisting of eight fas genes whose function in the infection will be discussed.
The role of the phytohormone cytokinin (CK) in this pathogenesis will be examined. Next, chemical ecology of plant-Insect interactions will be presented focusing on indirect defences such as extrafloral nectar (EFN) secretion and volatile organic compound (VOC) emission. Plant traits that do not directly affect herbivores but function by attraction or nourishment of predatory organisms are termed as indirect defences. These defences albeit contributing to a plant ecological success do not, however, come without fitness costs. Results supporting the optimal defence hypothesis, which predicts the spatio-temporal patterns of adaptive defence allocation within a plant will be shown. The role of light quality signals and JA-Ile, the active amino acid conjugate of phytohormone, jasmonic acid (JA) in regulating EFN secretion will be presented. Although JA-regulated indirect defences have been extensively investigated in higher plants, very little is known in lower plants. VOC emission in the invasive bracken fern and implications for the evolution and ancestral function of plant VOCs will be discussed.