Abstract
Treatment with Ca2+ channel blockers such as lanthanum chloride and verapamil promoted abscission in pulvinar explants of bean (Phaseolus vulgaris L. ev. Pirate). In addition, auxin‐induced delay of abscission was markedly reduced in the presence of Ca2+ channel blockers. In vitro phosphorylation studies were performed using membrane preparations (130000 g pellet) from freshly excised as well as auxintreated and control (minus auxin) pulvinar sections. Auxin‐treated sections showed a 66 kDa phosphoprotein as well as Ca2+ ‐dependent phosphorylation that were not observed in control explants.Coomassie blue stammg of soluble proteins (130000 g supernatent) separated on SDS‐PAGE revealed the presence of 62. 55 and 47 kDa polypeptides only in the freshly excised pulvini. However. no distinct changes were observed in soluble protein profile between auxin‐treated and control explants. When soluble proteins were phosphorylated in vitro, Ca2+ promoted the phosphorylation of 92, 55. 40 and I7 kDa polypeptides only in freshly excised pulvmi. Ca2+‐dependent phosphorylation of soluble proteins was not observed in either the control or auxin‐treated explants. In addition. in vivo phosphorylation studies were performed using freshly excised. auxrn‐treated and control explants. Freshly excused segments and auxin‐treated ex‐plants showed similar phosphoproteins, which were different from those observed mcontrol.
Published Version
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