【Abstract】 The plasma membrane fortion isolated from primp leaves of 14 d soybean shoot showed Protein kinase (PK) and protein phosphatase (PP) activities (Fig. 1 ), and these activities declined dramaically when the leaves underwent senescence-inducing treatment (Table 1 ). 6-BA pretreatment, which showed retarding effect on soybean leaf senescence, could sustain the activities of both PKs and PPs during the senescence-inducing treatment (Table 1 ). The results of autoradiogra phy suggested that the main PKs whose activities declined during leaf senescence were calcium-dependent Protein kinases (Fig. 3). The potent and specif ic inhibitor of Protein phosphatase 1 and 2A, okadric acid, could fasten leaf senescence. These results impied thatretaining the balance of plasma membrane protein phosphorylation/ dephosphorylation was the key action of exogenous 6-BA in retarding leat senescence.更多还原