Changes in the accumulation of alfa- and beta-tubulin during bud development in Vitis vinifera L.

Microtubules play important roles duringgrowth and morphogenesis of plant cells. Multiple isoformsof - and -tubulin accumulate in higher plant cells andoriginate either by transcription of diVerent genes or bypost-translational modiWcations. The use of diVerenttubulin isoforms involves the binding of microtubules todiVerent associated proteins and therefore generates microtubuleswith diVerent organizations and functions. Tubulinisoforms are diVerentially expressed in vegetative andreproductive structures according to the developmental programof plants. In grapevine (Vitis vinifera L.), vegetativeand reproductive structures appear on the same stem, makingthis plant species an excellent model to study the accumulationof tubulin isoforms. Proteins were extracted fromgrapevine samples (buds, leaves, Xowers and tendrils)using an optimized extraction protocol, separated by twodimensionalelectrophoresis and analyzed by immunoblotwith anti-tubulin antibodies. We identiWed eight -tubulinand seven -tubulin isoforms with pI around 4.8–5 thatgroup into separate clusters. More acidic -tubulin isoformswere detected in buds, while more basic -isoforms wereprevalently found in tendrils and Xowers. Similarly, moreacidic -tubulin isoforms were used in the bud stage whilea basic -tubulin isoform was essentially used in leaves andtwo central -tubulin isoforms were characteristically usedin tendrils and Xowers. Acetylated -tubulin was notdetected in any sample while tyrosinated -tubulin wasessentially found in large latent buds and in bursting budsin association with a distinct subset of tubulin isoforms