Azospirillum-plant relationships: physiological, molecular, agricultural, and environmental advances (1997-2003)

• Published in: Canadian journal of microbiology Vol. 50; no. 8; pp. 521 - 577
• Main Authors: Bashan, Y, Holguin, G, de-Bashan, L.E
• Format: Journal Article
• Language: English
• Published: Ottawa, Canada NRC Research Press 01.08.2004; National Research Council of Canada; Canadian Science Publishing NRC Research Press
• Subjects: Adsorption; Agriculture; Azospirillum; Azospirillum - classification; Azospirillum - genetics; Azospirillum - physiology; Bacteria; bacterial colonization; Bacteriology; Biological and medical sciences; Botany; Cations; classification; Environmental conditions; Fundamental and applied biological sciences. Psychology; Genetics; genomics; growth & development; literature reviews; metabolism; microbial physiology; Microbiology; Microorganisms; molecular genetics; Pathogenicity, virulence, toxins, bacteriocins, pyrogens, host-bacteria relations, miscellaneous strains; Pesticides; Physiology; Plant Development; Plant ecology; Plant growth; Plant Growth Regulators; Plant Growth Regulators - metabolism; plant growth-promoting rhizobacteria; Plant Roots; Plant Roots - growth & development; Plant Roots - microbiology; Plants; Plants - microbiology; Rhizosphere; Roots; Saccharides; Seedlings; Soil Microbiology; Spring wheat; Rhizosphere; Spirillales; Interaction; Azospirillum; Spirillaceae; Bacteria; Environment; Physiology; Review; Genome
• ISSN: 0008-4166; 1480-3275
• DOI: 10.1139/w04-035

This review presents a critical and comprehensive documentation and analysis of the developments in agricultural, environmental, molecular, and physiological studies related to Azospirillum cells, and to Azospirillum interactions with plants, based solely on information published between 1997 and 2003. It was designed as an update of previous reviews (Bashan and Levanony 1990; Bashan and Holguin 1997a), with a similar scope of interest. Apart from an update and critical analysis of the current knowledge, this review focuses on the central issues of Azospirillum research today, such as, (i) physiological and molecular studies as a general model for rhizosphere bacteria; (ii) co-inoculation with other microorganisms; (iii) hormonal studies and re-consideration of the nitrogen contribution by the bacteria under specific environmental conditions; (iv) proposed Azospirillum as a non-specific plant-growth-promoting bacterium; (v) re-introduction of the "Additive Hypothesis," which suggests involvement of multiple mechanisms employed by the bacteria to affect plant growth; (vi) comment on the less researched areas, such as inoculant and pesticide research; and (vii) proposes possible avenues for the exploitation of this bacterium in environmental areas other than agriculture.Key words: Azospirillum, plant-bacteria interaction, plant-growth-promoting bacteria, PGPB, PGPR, rhizosphere bacteria.