Transport interactions between paraquat and polyamines in roots of intact maize seedlings

• Published in: Plant physiology (Bethesda) Vol. 99; no. 4; pp. 1400 - 1405
• Main Authors: Hart, J.J. (US Plant, Soil and Nutrition Laboratory, USDA, ARS, Ithaca, NY), DiTomaso, J.M, Linscott, D.L, Kochian, L.V
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01.08.1992
• Subjects: Agronomy. Soil science and plant productions; AMINAS BIOGENICAS; AMINE BIOGENE; Amines; Biological and medical sciences; Cell membranes; Chemical control; Corn; Diamines; ESPERMINA; FISIOLOGIA VEGETAL; Fundamental and applied biological sciences. Psychology; Kinetics; mechanisms; Membranes and Bioenergetics; PARACUAT; PARAQUAT; Parasitic plants. Weeds; PHYSIOLOGIE VEGETALE; Phytopathology. Animal pests. Plant and forest protection; Plant roots; Plants; PLANTULAS; PLANTULE; Polyamines; PUTRESCINA; PUTRESCINE; RACINE; RAICES; roots; Seedlings; SPERMINE; transport; Weeds; ZEA MAYS; Cadaverine; Monocotyledones; Polyamine; Zea mays; Root; Plant juvenile growth stage; Putrescine; Herbicide; Cereal crop; Quaternary ammonium compound; Proteins; Plasmalemma; Absorption; Spermine; Gramineae; Membrane transport; Angiospermae; Paraquat; Spermatophyta
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.99.4.1400

Interactions between absorption of paraquat and the polyamines putrescine, cadaverine, and spermine in roots of intact maize (Zea mays L. cv 3377 Pioneer) seedlings were examined. Concentration-dependent kinetics for paraquat and putrescine influx were similar and both kinetic curves could be resolved into a linear and a saturable component. The linear component was previously shown to represent cell wall/membrane binding. The saturable components for paraquat and putrescine uptake, which represent influx across the plasmalemma, had Km values of 98 and 120 micromolar, respectively, and Vmax values of 445 and 456 nanomoles per gram fresh weight per hour, respectively. Lineweaver-Burk transformation of the saturable component of paraquat influx in the presence of varying concentrations of putrescine indicated that the diamine competitively inhibited the saturable component of paraquat uptake. Reciprocal experiments similarly demonstrated that paraquat competitively inhibited the saturable component of putrescine uptake. Competitive inhibition of both paraquat and putrescine influx could also be demonstrated with the diamine cadaverine, which has a charge distribution similar to that of paraquat and putrescine. In contrast, the larger, tetravalent polyamine spermine appeared to noncompetitively inhibit the influx of paraquat and putrescine. These results strongly suggest that paraquat enters maize root cells via a carrier system that normally functions in the transport of diamines with a charge distribution similar to that of paraquat