Chemical characterization of root exudates from rice (Oryza sativa) and their effects on the chemotactic response of endophytic bacteria |
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Authors: | Bacilio-Jiménez Macario Aguilar-Flores Sara Ventura-Zapata Elsa Pérez-Campos Eduardo Bouquelet Stephane Zenteno Edgar |
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Institution: | (1) Departamento de Bioquímica, Instituto Nacional de Enfermedades Respiratorias, Tlalpan D.F., 14080, Mexico;(2) Microbiología Ambiental, Centro de Investigaciones Biológicas del Noroeste, La Paz B.C.S., 23000, Mexico;(3) Departamento de Botánica de la Escuela Nacional de Ciencias Biológicas, I. P. N., Laboratorio de Fisiología Vegetal, 45873, Mexico;(4) Departamento de Biotecnología, Centro de Desarrollo de Productos Bióticos, I. P. N. Yautepec, Morelos, 62731, México;(5) Laboratoire de Chimie Biologique de la Université des Sciences et Technologies de Lille, UMR du CNRS No. 8576, Villeneuve d'Ascq, 59655 Cedex, France;(6) Departamento de Bioquímica, Facultad de Medicina, UNAM, Laboratorio de Inmunología, 04510, Mexico |
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Abstract: | Root exudates represent an important source of nutrients for microorganisms in the rhizosphere and seem to participate in early colonization inducing chemotactic responses of rhizospheric bacteria. We characterized the root exudates collected from rice plantlets cultured under hydroponic conditions and assessed their effects on the chemotaxis of two strains of endophytic bacteria, Corynebacterium flavescens and Bacillus pumilus, collected from the rice rhizosphere. We compared these chemotactic effects on endophytic bacteria with those on two strains of plant-growth-promoting bacteria, Azospirillum brasilense (isolated from the corn rhizosphere) and Bacillus sp. (from the rice rhizosphere). The root exudates were collected at different time intervals. The highest concentration and diversity of amino acids and carbohydrates were found during the first 2 weeks after seeding. Histidine, proline, valine, alanine, and glycine were the main amino acid residues identified during the 4 weeks of culture. The main carbohydrates identified were glucose, arabinose, mannose, galactose, and glucuronic acid. The chemotactic responses of the analyzed endophytic bacteria to root exudates were 3.9 to 5.1 times higher than those of A. brasilense and 2.2 to 2.8 times higher than Bacillus sp. Our results indicate that rice exudates may induce a higher chemotactic response for endophytic bacteria than for other bacterial strains present in the rice rhizosphere. |
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Keywords: | endophytic bacteria chemotaxis plant-growth-promoting bacteria root exudates rice |
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