Abscisic Acid, Microtubules and Phospholipase D-Solving a Cellular Bermuda Triangle.

Rice plants are important food crops that are sensitive to cold stress. Microtubules (MTs) are highly associated with plant response to cold stress. The exogenous application of abscisic acid (ABA) can transiently induce the cold stability of microtubules. These phenotypes were accompanied by the transient increase in Phospholipase D (PLD) enzyme activity. The analysis of detyrosinated/tyrosinated α-tubulin by Western blot in the NtTUA3 line or in the NtTUA3+OsTTL line gave us such a conclusion that the effect of ABA on detyrosinated α-tubulin not only was regulated by ABA but also was dependent on the TTLL12 protein. The dual ABA and 1% n-butanol treatments had shown that ABA-induced detyrosinated α-tubulin in a manner distinct from the n-butanol pathway. Detecting the detyrosinated α-tubulin level after pre-treatment with pertussis toxin (PTX), a G-protein inhibitor, followed by ABA, as well as mastoparan (Mas7) treatment suggested that the effect of ABA on detyrosinated α-tubulin was dependent on PLD activity.