Tubulin Isotypes in Rye Roots Are Altered during Cold Acclimation

The cold stability of cortical microtubules in root-tip cells of winter rye (Secale cereale L. cv Puma) is altered by growth temperature (GP Kerr, JV Carter [1990] Plant Physiol 93:77-82). One hypothesis for the basis of this alteration is that different tubulin isotypes are present at different growth temperatures, and that the cold stability of microtubules is affected by these isotypic differences. We have explored the first part of this hypothesis by comparing protein extracts from roots of seedlings grown for 2 days at 22 degrees C (nonacclimated) or for an additional 2 or 4 days at 4 degrees C (cold-acclimated). Immunoblots of two-dimensional polyacrylamide gels were probed with monoclonal antibodies to alpha- and beta-tubulin. At least six alpha- and seven beta-tubulins were present in the extracts from both the nonacclimated and cold-acclimated roots. Changes in electrophoretic mobility and isotype number of both alpha- and beta-tubulin were observed after only 2 days at 4 degrees C. Further changes in tubulin were observed after 4 days at 4 degrees C. Changes in alpha-tubulin were more pronounced than those in beta-tubulin.