Ringing induces the accumulation of vegetative storage proteins in poplar bark

Poplar branches were ringed in late spring to determine whether the interruption of the phloem flow could induce the accumulation of vegetative storage proteins (VSPs) in the bark of adult trees. Eight days after ringing, an increased deposition of starch as well as a premature rise in the soluble-protein level occurred in the bark tissues located 1 cm above the ring. Changes in the SDS-PAGE pattern of bark proteins were characterized by the accumulation of three polypeptides (32, 36 and 38 kDa), which exhibited the same molecular weight as VSPs described in poplar bark during winter, cross-reacted to antibodies raised against a poplar VSP, and bound to several lectins in the same way as poplar bark VSPs. These results indicate that during the vegetative period, ringing induces the accumulation of VSPs in the bark of poplar.