Graduate student
Dennis M. Lee

The search for tex

The gene TCH4 (XTH22), encodes a xyloglucan transglucosylase/hydrolase. It exhibits an increase transcription rate in response to touch and other various stimuli including heat, cold, and darkness. Current evidence suggests that all of these various stimuli may be transduced at least partially through a common signal transduction pathway.

We have undertaken a mutant screen to find genetic elements in this pathway. Starting with a transgenic plant containing a firefly luciferase reporter construct driven with the upstream regulatory region of TCH4, we isolated putative mutants exhibiting various alterations in magnitude or kinetics of luciferase expression. Northern analyses of TCH4 mRNA verify that the effect of the mutations are on TCH regulation of expression.

The genes defective in the tex mutants must encode components necessary for the perception and response to environmental stimuli, such as heat and touch. Our long term goal is to clone these genes to identify the nature of a "touch" receptor and the signal transduction components that lead to mechanosensitive gene regulation of expression.

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