Photoregulation of beta-Tubulin mRNA Abundance in Etiolated Oat and Barley Seedlings.

The effect of light on the abundance of beta-tubulin mRNA was measured in etiolated Avena sativa L. and Hordeum vulgare L. seedlings. Slot blot analysis employing an oat beta-tubulin cDNA clone was used to measure beta-tubulin mRNA levels. White light induced a 45% decrease in oat beta-tubulin mRNA abundance by 2 hours after transfer. A saturating red light pulse induced 40 and 55% decreases in beta-tubulin mRNA levels in oats and barley, respectively. Recovery of beta-tubulin mRNA levels was observed after a red light pulse but not after transfer to continuous white light. The red light induced decrease in oat beta-tubulin mRNA abundance was not reversible by a subsequent far-red light treatment. The mesocotyl portion of etiolated oat seedlings exhibited a more dramatic decrease in beta-tubulin mRNA abundance in response to red light than did the coleoptile portion. The results indicate that the well-documented effects of red light on the growth of etiolated seedlings are accompanied by changes in the expression of the beta-tubulin genes.