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Authors Jenkins, MB
Author Full Name Jenkins, MB
Title Rhizobial and bradyrhizobial symbionts of mesquite from the Sonoran Desert: salt tolerance, facultative halophily and nitrate respiration
Source SOIL BIOLOGY & BIOCHEMISTRY
Language English
Document Type Article
Author Keywords mesquite; Prosopis; Rhizobhun; Bradyrhizobiuni; salt tolerance; halophily; nitrate respiration; denitrification
Keywords Plus COWPEA RHIZOBIA; PROSOPIS-GLANDULOSA; NODULATING RHIZOBIA; NITROGEN-FIXATION; ANAEROBIC GROWTH; TREE LEGUMES; DENITRIFICATION; SALINITY; POPULATIONS; SODIUM
Abstract Rhizobial symbionts were isolated from the surface (0-0.5 M) and phreatic (3.9-5.0 M) root environments of a mature mesquite woodland in the Sonoran Desert of Southern California, and from variable depths (0-12 m) of non-phreatic mesquite ecosystems in the Chihuahuan Desert of New Mexico. They were tested for their ability to tolerate high salinity, and respire NO3- as mechanisms of free-living survival. Sixteen of 25 isolates were grown in yeast-extract mannitol (YEM) broth at NaCl concentrations of 2 (basal concentration), 100, 300, 500 and 600 mM, and their specific growth rates, cell dry weight and lag times were determined. Twenty of the 25 isolates were also grown in YEM broth under anaerobic conditions with or without 10 mM KNO3. Three categories of NaCl salinity responses were observed: (1) eight isolates showed decreased specific growth rates at NaCl concentrations of 100, 300 and 500 mM, but they nevertheless remained viable at 500 mM NaCl concentration; (2) the specific growth rate of six isolates increased significantly at 100 and 300 mM NaCl; and (3) specific growth rates of two isolates were significantly greater than the base-rate at all concentrations of NaCl. Five of 11 of the Bradyrhizobium isolates tested respired NO3-, but showed no growth. Seven Rhizobium isolates, three from the deep (3.9-5 m) phreatic rhizobial community, and four from the surface community denitrified NO3- but only the isolates from the phreatic community displayed anaerobic growth. Long-term interactions between rhizobial and bradyrhizobial communities and the surface and phreatic root environments of the mature Sonoran Desert mesquite woodland appear to have selected for strains of NO3- respiring rhizobia, general salt tolerance of both rhizobial and bradyrhizobial symbionts, and strains of weak facultative halophilic bradyrhizobia. These survival characteristics of mesquite rhizobia may be important regarding mesquite's establishment and long-term productivity in marginal desert soils, and may provide novel types of rhizobia for food crops growing in harsh environments. Published by Elsevier Ltd.
Author Address USDA ARS, Natl Resource Conservat Ctr, Watkinsville, GA 30677 USA
Reprint Address Jenkins, MB (corresponding author), USDA ARS, Natl Resource Conservat Ctr, 1420 Expt Stn Rd, Watkinsville, GA 30677 USA.
Times Cited 14
Total Times Cited Count (WoS, BCI, and CSCD) 15
Publisher PERGAMON-ELSEVIER SCIENCE LTD
Publisher City OXFORD
Publisher Address THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND
ISSN 0038-0717
29-Character Source Abbreviation SOIL BIOL BIOCHEM
ISO Source Abbreviation Soil Biol. Biochem.
Publication Date DEC
Year Published 2003
Volume 35
Issue 12
Beginning Page 1675
Ending Page 1682
Digital Object Identifier (DOI) 10.1016/j.soilbio.2003.08.014
Page Count 8
Web of Science Category Soil Science
Subject Category Agriculture
Document Delivery Number 742NK
Unique Article Identifier WOS:000186523800016
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