Brassinolides promote the expression of a new Cicer arietinum beta-tubulin gene involved in the epicotyl elongation.

A cDNA clone, CanTUB, encoding a putative beta-tubulin protein was isolated from a cDNA library constructed from 5-day old chickpea (Cicer arietinum) epicotyls. Analysis of its deduced amino acid sequence showed all the typical structural motifs of plant beta-tubulins. Putative sequences for autoregulation and tubulin mRNA stability, GTP and Ca2+/MAPs (microtubule-associated proteins) binding sites were present. Southern blot analysis of chickpea genomic DNA revealed that there are multiple beta-tubulin genes. The level of expression of beta-tubulin genes was correlated with the rate of growth in either seedlings and adult plants. The transcript levels of beta-tubulin genes were higher in actively elongating tissues such as etiolated epicotyls, roots and stem tissues of adult plants. Brassinolide-induced growth in chickpea epicotyls was accompanied by promotion of the expression of the gene coding for beta-tubulin.