Two-dimensional gel/western blot analysis was used to characterize α- and β-tubulin isotype expression along the developmental axis of the maize (Zea mays) seedling primary root. We identified four distinct α-tubulin isotypes and a minimum of six β-tubulin isotypes. This analysis showed differences between the α- and β-tubulin isotypes expressed in rapidly dividing tissue at the root tip and differentiated root tissues proximal to the tip. The α1 and α4 isotypes predominated in samples from immature rapidly dividing tissues such as root tips, whereas in mature tissues such as differentiated root and pollen, α2, a3 and α4 isotypes predominated. The β1 and β2 isotypes were more abundant in protein samples from root cortex than in samples from the root tip or vascular cylinder. In contrast, the β4 and β5 isotypes appeared to be more abundant in root tip and vascular cylinder samples than in root cortex samples. Hybridization probes from the 3′ non-coding region of six α-tubulin cDNA clones were used to quantify the levels of corresponding tubulin transcripts in selected tissues, from embryonic to mature and from largely undifferentiated to highly differentiated. The results from these hybridization experiments showed that all of the α-tubulin genes were expressed in all tissues examined, although each gene showed a unique pattern of differential transcript accumulation. A transcript produced from cDNA clone representing the tua5 α-tubulin gene was translated in vitro and produced an α-tubulin that comigrated with the α2 isotype.
Bibliographical noteFunding Information:
We thank Burle Gengenbach and the Department of Agronomy and Plant Genetics, University of Minnesota for providing field space and valuable advice. We are grateful to Gianni Piperno for providing tubulin antibodies and Sue Wick for critical reading of the manuscript. This work was supported by funds from c’.S. Department of Agriculture competitive research grants USDA 85.CRCR-l-1754, USDA 89-37261-4891 and USDA-89-37261-4910.
Copyright 2014 Elsevier B.V., All rights reserved.
- gene expression
- root development