Morphological Responses and Molecular Modifications in Tomato Plants after Mechanical Stimulation

Study of the growth responses of Lycopersicon escu-lentum (Mill.cv. VFN8) to mechanical stimulation applied to a single younginternode showed a rapid and sharp decrease in stem elongationand an inhibition of elongation of several internodes, indicativeof information transmission in the plant. A new tomato cDNApartial clone encoding calmodulin was isolated and used to studythe time course of the gene induction in response to the rubbingtreatment. Northern blot analysis showed a maximum accumulationof calmodulin mRNA 2 h after mechanical stimulation, not onlyin the rubbed internode, but also in upper and lower internodesand in young leaves. Treatment of the plant with calcium andEGTA showed the involvement of calcium and, in particular, intracellularcalcium in calmodulin gene expression and cellular response. (Received February 10, 1997; Accepted July 11, 1997)