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Helping Plants Survive Heat

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Science  21 Sep 2007:
Vol. 317, Issue 5845, pp. 1653
DOI: 10.1126/science.317.5845.1653c

Plants rely on microorganisms in the local environment for various important processes, one of which is nitrogen fixation by symbiotic bacteria that colonize the roots of some plants. McLellan et al. provide evidence that fungi in the rhizosphere (the soil surrounding the plant roots) may also contribute to heat tolerance. Previously, two inhibitors of mammalian heat shock protein 90 (Hsp90) were discovered in extracts from Sonoran desert plant-associated fungi. McLellan et al. follow up this result by showing that monocillin I specifically binds and inhibits the chaperone activity of Arabidopsis Hsp90 in vitro. Exposure of Arabidopsis seedlings to monicillin increased the expression and abundance of the heat shock response protein AtHsp101. Pretreatment of seedlings with monicillin before what would be a lethal heat stress for untreated plants increased survival, and this protective effect required Hsp101. When Arabidopsis seedlings were cultured with the fungus that produces monicillin, hypocotyl elongation decreased; however, the plants tolerated heat stress much better in the presence of the fungus. — NRG

Plant Physiol. 145, 174 (2007).

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