Promotion of callus formation by non-injurious mechanical stimulation in bean stems.

We have examined the effect of non-injurious mechanical stimulation on callus formation of stem tissues. Mechanical stimulation by rubbing substantially promoted the wound-induced callus formation on the stems of beans (Phaseolus vulgaris L.). The promotion of callus formation also was observed in in vitro culture of the tissues excised from mechanically stimulated stems of beans. The results imply that mechanical stimulation induces some physiological changes preference for cell division in developing callus.