STIMULATION OF TOBACCO SHOOT REGENERATION BY ALTERNATING WEAK ELECTRIC-FIELD

Nicotiana tabacum morphogenetic callus was used to study the stimulati ve effects of external alternating electric currents of low level and low frequency on the cytodifferentiation processes. The N. tabacum cal li were grown on standard medium for shoot regeneration and subjected to electric currents (50 Hz, 0.1-50 mu A) during the whole period of t reatment (30 days). The number of shoots, total mass, DNA and protein content were measured for each callus sample at the end of the experim ent. The number of shoots increased by up to 300% for the samples stim ulated with 50 mu A although no significant changes were noted in tota l mass, DNA and protein content in the stimulated samples compared to control. We suggest that in the presence of the external electric curr ent, the callus cells become more sensitive to chemical signals (hormo nes and/or ions) in the culture medium. A series of changes in the act ivity of membrane components, as a consequence of the modulation of me mbrane potential by the external electric field, could support our hyp othesis. (C) 1998 Elsevier Science S.A.