Tubulin gene expression persists during all changes in microtubular arrays related to cell shaping in growing barley leaves

Levels of alpha-tubulin RNA were determined in consecutive leaf segments taken along young, growing barley leaves by Northern blotting. The leaves exhibited a developmental gradient typical of graminaceous species ranging from a meristem at the base to fully differentiated cells at the tip. The objective was to ascertain whether or not high steady-state tubulin RNA levels accompany characteristic changes in microtubular arrays known to occur during cell division and differentiation. Of particular interest was the differentiation zone comprising a succession of well defined changes in microtubular arrays that appear to be involved in the control of cell shaping. High steady-state levels of alpha-tubulin RNA vi ere observed during all phases of apparent microtubular activity. Almost immediately after completion of cell shaping, but only then, a dramatic loss in tubulin RNA commenced. The results are discussed in the context of how plants map accomplish changes in cortical microtubular arrays.