PHOTOREGULATION OF BETA-TUBULIN MESSENGER-RNA ABUNDANCE IN ETIOLATED OAT AND BARLEY SEEDLINGS

The effect of light on the abundance of β-tubulin mRNA was measured in etiolated Avena sativa L. and Hordeum vulgare L. seedlings. Slot blot analysis employing an oat β-tubulin cDNA clone was used to measure β-tubulin mRNA levels. White light induced a 45% decrease in oat β-tubulin mRNA abundance by 2 hours after transfer. A saturating red light pulse induced 40 and 55% decreases in β-tubulin mRNA levels in oats and barley, respectively. Recovery of β-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 β-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 β-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 β-tubulin genes.