Developmental expression and regulation by light of two closely related beta-tubulin genes in Lupinus albus.

We present here the characterization of a Lupinus albus beta-tubulin gene, TubB2, which is closely related to TubB1. Both TubB1 and TubB2 transcripts are present in the embryonic axis of lupin dry seeds. The patterns of developmental expression of TubB1 and TubB2 beta-tubulin genes are strongly correlated. Both genes are expressed at higher levels in hypocotyls of 7-day-old etiolated plants compared to hypocotyls from plants grown under light/dark cycles. When etiolated plants are exposed to continuous white light, differential changes in the steady state levels of the TubB1 and TubB2 mRNAs from hypocotyls are observed. These changes are accompanied by an inhibition of hypocotyl extension.