Levels of Polyamines and Kinetic Characterization of Their Uptake in the Soybean Pathogen Phytophthora sojae

Polyamines are ubiquitous biologically active aliphatic cations that are at least transiently available in the soil from decaying organic matter. Our objectives in this study were to characterize polyamine uptake kinetics in Phytophthora sojae zoospores and to quantify endogenous polyamines in hypha...

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Published in:	Applied and Environmental Microbiology Vol. 72; no. 5; pp. 3350 - 3356
Main Authors:	Chibucos, M. Constantine, Morris, Paul F
Format:	Journal Article
Language:	English
Published:	Washington, DC American Society for Microbiology 01-05-2006
Subjects:	Biological and medical sciences Biological Transport cadaverine chemical constituents of plants cytochemistry Fundamental and applied biological sciences. Psychology Gene Expression Regulation, Developmental Glycine max Glycine max - microbiology hyphae Kinetics Microbiology Mycology Pathogens physiological transport Phytophthora - growth & development Phytophthora - metabolism Phytophthora - pathogenicity Phytophthora sojae Plant Diseases - microbiology Plant Roots - metabolism Plant Roots - microbiology Polyamines Polyamines - metabolism putrescine Putrescine - metabolism roots seedlings Soil Microbiology Soybeans spermidine Spermidine - metabolism spermine transporters zoospores Phytophthora sojae Polyamine Plant pathogen Phycomycetes Glycine max Uptake Fungi Leguminosae Dicotyledones Angiospermae Spermatophyta Kinetics Thallophyta
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Summary:	Polyamines are ubiquitous biologically active aliphatic cations that are at least transiently available in the soil from decaying organic matter. Our objectives in this study were to characterize polyamine uptake kinetics in Phytophthora sojae zoospores and to quantify endogenous polyamines in hyphae, zoospores, and soybean roots. Zoospores contained 10 times more free putrescine than spermidine, while hyphae contained only 4 times as much free putrescine as spermidine. Zoospores contained no conjugated putrescine, but conjugated spermidine was present. Hyphae contained both conjugated putrescine and spermidine at levels comparable to the hyphal free putrescine and spermidine levels. In soybean roots, cadaverine was the most abundant polyamine, but only putrescine efflux was detected. The selective efflux of putrescine suggests that the regulation of polyamine availability is part of the overall plant strategy to influence microbial growth in the rhizosphere. In zoospores, uptake experiments with [1,4-¹⁴C]putrescine and [1,4-¹⁴C]spermidine confirmed the existence of high-affinity polyamine transport for both polyamines. Putrescine uptake was reduced by high levels of exogenous spermidine, but spermidine uptake was not reduced by exogenous putrescine. These observations suggest that P. sojae zoospores express at least two high-affinity polyamine transporters, one that is spermidine specific and a second that is putrescine specific or putrescine preferential. Disruption of polyamine uptake or metabolism has major effects on a wide range of cellular activities in other organisms and has been proposed as a potential control strategy for PHYTOPHTHORA: Inhibition of polyamine uptake may be a means of reducing the fitness of the zoospore along with subsequent developmental stages that precede infection.
Bibliography:	http://aem.asm.org/contents-by-date.0.shtml ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Corresponding author. Mailing address: Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403. Phone: (419) 372-0481. Fax: (419) 372-2024. E-mail: pmorris@bgnet.bgsu.edu.
ISSN:	0099-2240 1098-5336
DOI:	10.1128/AEM.72.5.3350-3356.2006