Bean leaf abscission: Tissue-specific accumulation of a cellulase mRNA.

We have previously reported the identification (Tucker et al., 1988, Plant Physiol. 88, 1257-1262) and sequence (Tucker and Milligan, 1991, Plant Physiol. 95, 928-933) of a cellulase cDNA associated with bean (Phaseolus vulgaris L.) leaf abscission. In-vitro transcripts of this cDNA clone were used to determine the distribution of the complementary cellulase mRNA in abscising zones using both in-situ and tissue-print hybridization techniques. The mRNA was found in two cell layers on either side of the fracture plane and was not limited to any particular cell class. In the vascular tissue, however, cellulase mRNA accumulated in cells up to several millimeters either side of the fracture plane. This distribution is consistent with immunolocalizations of cellulase in the same tissue.