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United States Department of Agriculture

Agricultural Research Service

Title: Recent Studies on the Microbial Ecology of Bacterial Endophytes in Plants

Authors
item Kloepper, J. - AUBURN UNIVERSITY
item Quadt-Hallmann, A. - AUBURN UNIVERSITY
item Mahaffee, Walter
item Hallman, J. - AUBURN UNIVERSITY

Submitted to: Proceedings Brazilian Soil Science Society
Publication Type: Proceedings
Publication Acceptance Date: September 1, 1997
Publication Date: N/A

Interpretive Summary: Endophytic bacteria are ubiquitous in most plant species, often residing latently in various tissues. Endophytes will be defined for this review as those bacteria that can be isolated from surface-disinfested plant tissue or extracted from within the plant and do not visibly harm the plant. Historically, the non-diazotrophic endophytic bacterial have been thought to be weakly virulent plant pathogens but have been recently discovered to have several beneficial effects on host plants, such as plant growth promotion and increased resistance against plant pathogens and parasites. Endophytic bacteria originate from the epiphytic bacterial communities of the rhizosphere and phyllosphere as well as from endophyte-infested seeds or planting materials. Besides gaining entrance to plants through natural openings or wounds, endophytic bacteria appear to actively penetrate plant tissues using hydrolytic enzymes like cellulase and pectinase. In general, endophytic bacteria occur at lower population densities than pathogens and, at least some of them, do not induce a hypersentive response in the plant which indicates that they are not recognized by the plant as being pathogens. Evoluntionarily, endophytes appear to be intermediate between saprophytic bacteria and plant pathogens. Overall, the endophytic microflora is of dynamic structure and is influenced by biotic and abiotic factors which also influence the soil and plant host.

Technical Abstract: Endophytic bacteria are ubiquitous in most plant species, often residing latently in various tissues. Endophytes will be defined for this review as those bacteria that can be isolated from surface- disinfested plant tissue or extracted from within the plant and do not visibly harm the plant. Historically, the non-diazotrophic endophytic bacterial have been thought to be weakly virulent plant pathogens but have been recently discovered to have several beneficial effects on host plants, such as plant growth promotion and increased resistance against plant pathogens and parasites. Endophytic bacteria originate from the epiphytic bacterial communities of the rhizosphere and phyllosphere as well as from endophyte-infested seeds or planting materials. Besides gaining entrance to plants through natural openings or wounds, endophytic bacteria appear to actively penetrate plant tissues using hydrolytic enzymes like cellulase and pectinase. In general, endophytic bacteria occur at lower population densities than pathogens and, at least some of them, do not induce a hypersentive response in the plant which indicates that they are not recognized by the plant as being pathogens. Evoluntionarily, endophytes appear to be intermediate between saprophytic bacteria and plant pathogens. Overall, the endophytic microflora is of dynamic structure and is influenced by biotic and abiotic factors which also influence the soil and plant host.

Last Modified: 10/20/2014
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