, with regard to plants: make the necessary physiological adjustments to minimize the fitness consequences of lost tissues. Tolerance may be the best strategy for a plant caught in cycles of defensive escalation with its herbivores to extricate itself.
Wild tobacco, which is native to North America, has developed sophisticated methods to fend off Manduca sexta larvae. For example, jasmonic acid produced after insect attack elicits the emission of volatiles that attract Manduca sexta predators. These insect predators kill caterpillars (Kessler and Baldwin, 2001). Yet even such a complex defense system does not guarantee the plantsTM survival. Therefore the plants have developed ways of tolerating defoliation by these insect pests: by bunkering resources in below-ground protected sites when they are attacked - just as humans do in crisis situations. In previous studies, Prof. Baldwin and his colleagues have shown that wild tobacco minimizes the production and transport of the toxin, nicotine, in the leaves when attacked by Manduca sexta, because the value of this defense is reduced against nicotine-adapted attackers. Nitrogen, which is part of nicotine, may be used more effectively in other ways.
This seems to apply to carbon, too, which is assimilated from carbon dioxide during photosynthesis. As important energy source, carbon is commonly stored as sugar or starch. The scientists found that molecules in the oral secretions of Manduca sexta larvae activate the downregulation of the expression of a protein kinase activator (GAL83) in the plant tissue via a signalling cascade that remains unknown. GAL83 is not unknown in the animal kingdom and in microorganisms: it is the beta-subunit of a protein complex (SNF1 related kinases), which regulates the use of glucose or galactose in mammals and yeast - especially during times of energy deficiency. SNF1 kinases function as posttranslational modificators and can up- or downregulate thPage: 1 2 3 Related biology news :1
Contact: Dr. Ian T. Baldwin
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