PARENT SESSION
Poster Session #3: Herbivory.
Monday, August 6, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall

Photosynthetic performance of remaining leaf tissue after folivory.

Hamilton, Jason¹, Miller, Tim¹, Crofts, Antony¹, Oxborough, Kevin², DeLucia, Evan¹, ^{1 2}

ABSTRACT- Effects of folivory on plant carbon assimilation are not necessarily limited to the tissues that are lost or damaged. Consequently, maps of photosynthetic activity within a plant are unlikely to coincide with maps of leaf damage. We have developed a novel chlorophyll fluorescence imaging system that provides detailed maps of the component reactions of photosynthesis across leaf surfaces. Our instrument extends the capabilities of previous instruments by (1) measuring Fo in addition to other steady-state fluorescence parameters Fm, Fm', F'; (2) imaging both rapid fluorescence induction kinetics and electron transfer in the two-electron gate of photosystem II; (3) allowing for imaged areas ranging from 4mm2 to 6cm2; and (4) allowing leaves to be free, attached to the plant, or held in a cuvette that allows for environmental control and simultaneous measurement of gas exchange parameters. We have found that apparent rates of electron transport in linden bean are reduced by 40% at > 5 mm from the point of herbivory by corn earworm. The ability to reduce photosynthesis away from the initial region of damage suggests that the effects of herbivory on plant production may have been greatly underestimated in the past. We are in process of modifying the instrument to simultaneously map chlorophyll fluorescence and gene transcription by fluorescence from green-fluorescent protein.

KEY WORDS: herbivory, photosynthesis, fluorescence, GFP