Brassinolides promote the expression of a new Cicer arietinum β-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.