Uvini Gunawardena, University of Arizona, Tucson, Arizona, USA
Xiaowen Zhao, University of Arizona, Tucson, Arizona, USA
Martha C Hawes, University of Arizona, Tucson, Arizona, USA
Published online: September 2006
DOI: 10.1002/9780470015902.a0002335.pub2
Diverse compounds exuded by different parts of the root system create a unique environment known as the rhizosphere. Interactions among microorganisms found within the rhizosphere and communication between these microorganisms and plant roots play an important role in maintaining plant health.
Keywords: mucilage; border cells; root cap; sloughed root cap cells; microbial ecology; root exudates
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Figure 1. Functional categories of root exudates.
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Figure 2. Sources and effects of root exudates. (a) Regions of the root known to release exudates. (b) Host-specific interactions of microorganisms with border cells: 1, release of border cells (arrow) into the environment; 2, induction of zoosphere germination by border cells; 3, binding of bacteria to border cells; 4, colonization of border cells by soil-borne fungus; 5, attraction of pathogenic nematode to border cells.
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Figure 3. Use of rhizosphere interactions for improvement of plant health and the environment.
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| References | |
| book Bolton H Jr and Fredrickson JK (1993) "Microbial ecology of the rhizosphere". In: Meeting FB Jr (ed.) Soil Microbial Ecology, pp. 27–57. New York: Marcel Dekker | |
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| Gunawardena V, Miyasaka S, Zhao X and Hawes MC (2000) Function of root border cells in plant defence. Trends in Plant Sciences 5: 128–133. | |
| Gunawardena U, Van Etten H and Hawes MC (2005) Tissue-specific localization of Pea (Pisum sativum L.) root infection by Nectria haematococca: mechanisms and consequences. Plant Physiology 137: 1363–1374. | |
| Hawes MC, Bengough GA, Cassab G and Ponce G (2003) Root caps and rhizosphere. Journal of Plant Growth Regulation 21: 352–367. | |
| Hawes MC, Brigham LA, Wen F, Woo HH and Zhu Y (1998) Function of root border cells in plant health: pioneers in the rhizosphere. Annual Review of Phytopathology 36: 311–327. | |
| Iijima M, Griffiths B and Bengough AG (2000) Sloughing of cap cells and carbon exudation from maize seedling roots in compacted sand. New Phytologist 145: 477–482. | |
| book Kennedy AC (1998) "The rhizosphere and spermosphere". In: Sylvia DM, Fuhrman JJ, Hartel PG and Zuberer DA (eds) Principles and Applications of Soil Microbiology, pp. 389–407. Englewood Cliffs, NJ: Prentice-Hall | |
| book Kloepper JW, Zablotowicz RM, Tipping EM and Lifshitz R (1991) "Growth promotion mediated by bacterial rhizosphere colonizers". In: Keister DL and Cregan PB (eds) The Rhizosphere and Plant Growth, pp. 315–326. Dordrecht, The Netherlands: Kluwer | |
| book Lynch JM and Whipps JM (1991) "Substrate flow in the rhizosphere". In: Keister DL and Cregan PB (eds) The Rhizosphere and Plant Growth, pp. 15–24. Dordrecht, The Netherlands: Kluwer | |
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| book Nelson EB (1991) "Exudate molecules initiating fungal responses to seeds and roots". In: Keister DL and Cregan PB (eds) The Rhizosphere and Plant Growth, pp. 197–209. Dordrecht, The Netherlands: Kluwer | |
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| Further Reading | |
| book Allen MF (ed.) (1992) Mycorrhizal Functioning: An Integrative Plant–Fungal Process. New York: Chapman & Hall. | |
| Beare MH, Coleman DC, Crossley DA Jr, Hendrix PF and Odum EP (1995) A hierarchical approach to evaluating the significance of soil biodiversity to biogeochemical cycling. Plant and Soil 170: 5–22. | |
| book Fitter A (1996) "Characteristics and functions of root systems". In: Waisel Y, Eshel A and Kafkafi U(eds) Plant Roots, The Hidden Half, pp. 1–20. New York: Marcel Dekker | |
| book Klein DA, Salzwedel JL and Dazzo FB (1990) "Microbial colonization of plant roots". In: Nakes JP and Hagedorn C (eds) Biotechnology of Plant–Microbe Interactions, pp. 189–225. New York: McGraw-Hill | |
| book Ogoshi A, Kobayashi K, Homma Y et al. (eds) (1997) Plant Growth-Promoting Rhizobacteria – Present Status and Future Prospects. The 4th PGPR International Workshop Organizing Committee 1997. Sapporo, Japan: Nakanishi Printing. | |
| Pierson LS III, Wood DW and Pierson EA (1998) Homoserine lactone-mediated gene regulation in plant-associated bacteria. Annual Review of Phytopathology 36: 207–225. | |
| book Rovira AD (1991) "Rhizosphere research – 85 years of progress and frustration". In: Keister DL and Cregan PB (eds) The Rhizosphere and Plant Growth, pp. 3–13. Dordrecht, The Netherlands: Kluwer | |
| book Stacey G, Mullin B and Gresshoff M (eds) (1996) Biology of Plant–Microbe Interactions. St. Paul, MN: International Society for Molecular Plant–Microbe Interactions. | |
| book Vance CP (1991) "Root–bacteria interaction: symbiotic nitrogen fixation". In: Waisel Y, Eshel A and Kafkafi U(eds) Plant Roots, The Hidden Half, pp. 723–767. New York: Marcel Dekker | |
| book Wilcox HE (1991) "Mycorrhizae". In: Waisel Y, Eshel A and Kafkafi U(eds) Plant Roots, The Hidden Half, pp. 689–721. New York: Marcel Dekker | |
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