Benzyladenine-Directed Transport of Carbon-14 and Phosphorus-32 in Senescing Bean Plants

Abstract

The distribution of radioactivity from applied sucrose.¹⁴C and ³²P to various plant parts were studied in relation to the retardation of leaf senescence by applied benzyladenine (BA) in intact bean plants. In short-time experiments sucrose-¹⁴C was fed to the plants for 48 h through the second trifoliate leaf at weekly intervals from the third to the eighth week after planting. In long-term experiments sucrose-¹⁴C was fed to all plants for 48 h at the third week and changes in distribution examined at weekly intervals up till the eight week. In both cases, BA applied to the primary leaves of intact bean plants did not cause a directed mobilization of sucrose-¹⁴C. When the plants were stripped, leaving the primary leaves and the terminal pod, and fed sucrose-¹⁴C or ³²P through the terminal leaflet of the second trifoliate leaf, the BA-treated leaf accumulated relatively more radioactivity than the opposite water-treated leaf. It was concluded that the retardation of senescence by BA in the primary leaves of intact bean plants does not result directly from the mobilization of metabolites and nutrients from other plant parts. It is therefore suggested that BA-induced longevity in the primary leaves of the intact plant is accomplished by metabolic self-sustenance.