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| Web URL(s): | http://archive.lib.msu.edu/tic/rpr/1995/Turfgrass/20425,%20Cornell,%20Nelson.PDF
Last checked: 11/11/2013
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| Publication Type:
| Report |
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| Material Type: | Manuscript |
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| Monographic Author(s): | Nelson, Eric B.; van Dijk, Karin; Maloney, Alan P. |
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| Author Affiliation: | Nelson: Associate Professor; van Dijk: Graduate Research Associate; and Maloney: Former Research Associate, Department of Plant Pathology, Cornell University, Ithaca, NY |
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| Monograph Title: | Genetic Basis of Biological Control in a Bacterium Antagonistic to Turfgrass Pathogens: [1995 Annual Research Report], 1995. |
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| Publishing Information: | Ithaca, New York: Department of Plant Pathology, Cornell University |
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| # of Pages: | 7 |
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| Collation: | [7] pp. |
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| Abstract/Contents: | "The main goal of our project on Enterobacter cloacae genetics has been to identify the genetic determinants for biocontrol traits in Enterobacter cloacae so that their role in the suppression of Pythium-incited diseases of turfgrasses can be specifically elucidated. Even though our focus has been on Pythium-incited diseases of creeping bentgrass, we believe our studies will have broad applicability to other bacterium-pathogen interactions. The objectives of our studies are to: 1) identify and clone DNA sequences that encode pathogen-suppressive properties in E. cloacae strain EcCT-501, 2) determine the nucleotide sequence of E. cloacae DNA encoding pathogen-suppressive properties and tentatively establish a function for the gene product, and 3) evaluate, in field studies, the expression of the biocontrol-related genes under typical turfgrass management conditions. Our studies in 1995 focussed [focused] primarily on objectives 1 and 2. During work in 1994, we spent considerable time studying mutant V58, which was a biocontrol negative mutant deficient in malate dehydrogenase activity. We further isolated other mutants lacking significant levels of biological control activity. One such mutant, 21-1, was the focus of our studies in 1995. These studies were concerned with establishing the role of fatty acid metabolism in biological control. The parent strain of Enterobacter cloacae, strain EcCT-501, suppresses several different Pythium species, including P. ultimum, P. aphanidermatum, and P. graminicola, on creeping bentgrass. Furthermore, this strain inactivates the stimulatory activity of creeping bentgrass seed exudate, as well as the exudate of many other crop plants, thus preventing responses of these Pythium species to plants. With P. ultimum in particular, sporangium germination is greatly reduced in the presence of strain EcCT-501. As a result, many of our studies focussed [focused] on interactions with P. ultimum on creeping bentgrass. From among all exudate components, long chain fatty acids (LCFA) are important stimulants of sporangium germination. Our work in 1995 centered on initial attempts to examine the role of LCFA catabolism in the expression of biological control properties in E. cloacae. Strain EcCT-501 reduced the stimulatory activity of the LCFA, linoleic acid, the most abundant LCFA found in creeping bentgrass and other plant seed exudates. A series of TnphoA mutants (Kanr) were screened for growth on linoleic acid as a sole carbon and energy source. One out of 5000 Kanr colonies was deficient in the ability to inactivate the stimulatory activity of creeping bentgrass seed exudate and linoleic acid to P. ultimum sporangium germination. Furthermore, this mutant, 21-1, no longer protected creeping bentgrass from Pythium seed and seedling disease. A cosmid, pKV1, mobilized into mutant 21-1, complemented the linoleic acid catabolic deficiencies and restored the ability to inactivate creeping bentgrass seed exudate stimulatory activity. Furthermore, this clone fully restored biological control properties to wild-type levels. Current evidence suggests a role of fatty acid metabolism in biological control properties in Enterobacter cloacae." |
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| Language: | English |
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| References: | 5 |
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| See Also: | See also related summary article "Genetic basis of biological control in a bacterium antagonistic to turfgrass pathogens" 1995 Turfgrass and Environmental Research Summary, 1995, pp. 52-53, R=20425. R=20425 |
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| Note: | Also appears as pp. 00075-00081 in the USGA Turfgrass Research Committee Reporting Binders for 1995.
"United States Golf Association Green Section Research Annual Report"
"October, 1995"
Tables
Graphs |
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| ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
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http://archive.lib.msu.edu/tic/rpr/1995/Turfgrass/20425,%20Cornell,%20Nelson.PDF
Last checked: 11/11/2013
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