Evidence for the involvement of glycanase activities in the dissociation of cortical cell walls during the emergence of callus from rice root tissues in the presence of 2,4-D.

Nojirimycin bisulfite andp-nitrophenyl-1-thio-ß-D-glucoside, potent inhibitors of ß-glucanase, suppressed cortical dissociation and callus growth in rice roots (Oryza sativa L. cv. Sasanishiki) in the presence of 2,4-D, with resultant suppression of the emergence of callus clumps from the interior of root tissues. These sugar analogs inhibited the 2,4-D-induced increase in the elastic and plastic compliance of cell walls but did not affect oxygen uptake by root explants in the presence of 2,4-D. They also inhibited the activities of CM-cellulase, ß-glucosidase and α-arabinosidase in 2 M NaCl-soluble and/or buffer-soluble fractions of crude root extracts. Involvement of glycan hydrolase activities in cell wall dissociation during callus emergence is discussed.