BIOLOGY, BIOLOGICAL CONTROL, AND MOLECULAR GENETICS OF ROOT DISEASES OF WHEAT, BARLEY AND BIOFUELS BRASSICAS
Location: Root Disease and Biological Control Research
Title: Rhizosphere engineering and management for sustainable agriculture
Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 20, 2009
Publication Date: August 20, 2009
Citation: Peter, R.R., Dessaux, Y., Thomashow, L.S., Weller, D.M. 2009. Rhizosphere engineering and management for sustainable agriculture. Plant and Soil Journal, 321 (1-2): 363-383.
Interpretive Summary: Plants live in a symbiotic relationship with large communities of beneficial root-associated microorganisms that serve as a living buffer against soilborne pathogens. Both the plant and the beneficial bacteria can be engineered to enhance plant health and productivity.
Engineering of the plant can involve genetic modification of processes that affect growth either directly or indirectly. For example, plants can be engineered to increase the bioavailability of nutrients, reduce the impact of environmental stresses, encourage the growth of beneficial root-associated bacteria, or interfere with the proliferation of certain root pathogens. Alternatively, the beneficial root-associated bacteria can be engineered to interfere with the synthesis of stress-induced hormones that retard root growth or to produce antibiotics effective against root pathogens. Certain agronomic practices such as the cultivation of crops that select microbial populations suppressive of soilborne pathogens, and the use of soil amendments that favor the development of beneficial microbial populations, also constitute sustainable agricultural practices.
Molecular tools and biotechnological practices will continue to provide knowledge of the complex chemical and biological interactions that occur on plant roots, assuring that strategies used to engineer the rhizosphere will be safe, beneficial to productivity, and consistent with agricultural sustainability.
This paper reviews strategies for manipulating plants and their root-associated microorganisms to improve plant health and productivity. Some strategies directly target plant processes that impact on growth, while others are based on our knowledge of interactions among the components of the rhizosphere (roots, microorganisms and soil). For instance, plants can be engineered to modify the rhizosphere pH or to release compounds that improve nutrient availability, protect against biotic and abiotic stresses, or encourage the proliferation of beneficial microorganisms. Rhizobacteria that promote plant growth have been engineered to interfere with the synthesis of stress-induced hormones such as ethylene, which retards root growth, and to produce antibiotics and lytic enzymes active against soilborne root pathogens. Rhizosphere engineering also can involve the selection by plants of beneficial microbial populations. For example, some crop species or cultivars select for and support populations of antibiotic-producing strains that play a major role in soils naturally suppressive to soil-borne fungal pathogens. The fitness of root-associated bacterial communities also can be enhanced by soil amendment, a process that has allowed the selection of bacterial consortia that can interfere with bacterial pathogens. Plants also can be engineered specifically to influence their associated bacteria, as exemplified by quorum quenching strategies that suppress the virulence of pathogens of the genus Pectobacterium. New molecular tools and powerful biotechnological advances will continue to provide a more complete knowledge of the complex chemical and biological interactions that occur in the rhizosphere, ensuring that strategies to engineer the rhizosphere are safe, beneficial to productivity, and substantially improve the sustainability of agricultural systems.