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

Day: 25th Feb 2014, Tuesday

Time: 4pm

Tea/Coffee: 3:45pm

Venue: CES Seminar Hall, 3rd Floor, Biological Sciences Building.

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朴athogen 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痴 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.