Endogenous oscillations of electric potential difference in the cambial region of the pine stem. II. Possible involvement of the oscillations in xylogenesis

Abstract

Direct and indirect interrelations between xylogenic processes and the endogenous electric potential difference (PD) oscillations generated in the cambial region of isolated tissue blocks from pine trunks were investigated. The frequency of transient PD changes varied during the season and displayed three minima which were concurrent with periods of initiation and termination of cambial activity and with the time of transition from early- to late-wood production. The oscillations were damped by TIBA - an inhibitor of polar auxin transport and stimulated by IAA, but only when the hormone was supplied to the apical end of the tissue block. This suggests that the polar transport of auxin may be involved in generation of the transient PD changes. Results of 2-channel recordings in one tissue block suggest that a part of the recorded oscillations (10-25 %) exhibit coordination in space and time: a wave-like pattern along the trunk axis is created by PD changes. The pattern might be a physical carrier of information coordinating processes of growth and differentiation in distant parts of the tree.