EFFECT OF ABSCISIC ACID AND COLD ACCLIMATION ON THE CYTOSKELETAL AND PHOSPHORYLATED PROTEINS IN DIFFERENT CULTIVARS OFTRITICUM AESTIVUML

Abstract

In winter wheat, the tubulin and 60 kDa-phosphorylated proteins/actin ratio is considerably higher in the roots than in the leaves. Differences in the content of the main cytoskeletal proteins were also found in the leaves of the different cultivars. It is suggested that the lower amount of the tubulin and 60 kDa-phosphorylated proteins and higher content of actin determine the greater tubulin cytoskeletal stability in the leaves and their higher frost resistance, as compared with the roots. Also, it is possible that the higher content of the tubulin and 60 kDa-phosphorylated proteins defines the lower microtubule (MT) stability in the leaves of the low frost resistant cultivar than in the leaves of the more frost resistant ones. In the roots and leaves of the low frost resistant cultivar, the low stability of the numerous tubulin structures is apparently one reason for the abscisic acid (ABA)-induced reduction of the cytoskeletal and 60 kDa-phosphorylated proteins in the cells. The cold acclimation compensated the ABA effect in the roots of the very frost resistant cultivar in the most extent. This suggests the existence of the different pathways in the increased plant cell frost resistance through the action of ABA and low temperature.

Introns are key regulatory elements of rice tubulin expression

“…Plant hormones, including ABA, can affect tubulin gene expression (Mendu and Silflow 1994;Qin et al 1997;Olinevich et al 2002). It was previously reported that ABA can drastically reduce the amount of tubulin mRNA in elongating rice coleoptiles, leaving substantially unaffected the corresponding amount of tubulin protein (Gianı`et al 1998).…”

“…For all of these a-tubulin isotypes, we deciphered the contribution to gene expression provided by different putative regulatory elements. In addition, since it was shown that abscisic acid (ABA) can strongly reduce the amount of tubulin mRNA (Gianı`et al 1998) and protein (Olinevich et al 2002) we investigated its possible influence on the promoter activity of the rice gene encoding a2-and a3-tubulin isotypes.…”

Effects of phytohormones on the cytoskeleton of the plant cell

“…MT stability induced by ABA is recommended as a diagnostic marker of cold tolerance of various winter wheat cultivars [64]. Accli mation to low temperatures (hardening) and ABA treatment confer the higher stability to the cytoskeletal proteins [65]. Cold acclimation of various winter wheat cultivars differing in their frost resistance resulted in MT aggregation, increased fluorescence and stability of MTs and MFs predominantly in the root differentiation zone, whereas ABA induced simi lar changes in the meristem and elongation zone [61].…”

“…MT stabilization under the influence of low tempera tures can be also provided by phosphorylation of α or β tubulins on serine, threonine, and tyrosine residues [67]. In addition, in various winter wheat cultivars, the high content of phosphorylated 60 kD proteins, may be comprising actin and tubulin, was accompanied by a decrease in MT cold resistance [65]. ABA can decrease the amount of phosphorylated proteins, thus enhancing MT cold tolerance [65].…”

“…In addition, in various winter wheat cultivars, the high content of phosphorylated 60 kD proteins, may be comprising actin and tubulin, was accompanied by a decrease in MT cold resistance [65]. ABA can decrease the amount of phosphorylated proteins, thus enhancing MT cold tolerance [65].…”