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Title:Verticillium Dahliae Klebsiella Growth as It Relates to the Nitrogen, Sugars, and Water Potential of Tree Sap
Author(s):Duncan, David Robert
Department / Program:Plant Pathology
Discipline:Plant Pathology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Agriculture, Plant Pathology
Abstract:In vitro studies were conducted to determine the effects ammonium, amino acids, sugars and physical tension would have on the dry weight and conidial production of Verticillium dahliae Kleb.
Ammonium reduced dry weight and conidial production on nonbuffered Czapeks-Dox agar (CDA) of all isolates tested. On buffered ammonium amended media, dry weight production was comparable to that induced by other nitrogen sources. Conidial production was always suppressed.
The results of this study were discussed in terms of their implications concerning V. dahliae growth within xylem vessels of trees.
Asparagine, alanine, threonine or glutamine added to media containing ammonium prevented the ammonium-linked inhibition of dry weight production, but conidial production was still repressed. Leucine, valine and sodium nitrate did not prevent ammonium effects.
On mixtures of asparagine and ammonium, dry weight production was not reduced by high concentrations of ammonium or by a -30 bars water potential. Conidial production was always suppressed.
In sugar maple sap, ammonium induced abundant growth but conidial production was suppressed.
On amino acid amended CDA, extensive variation occurred in both conidial and dry weight production depending upon the amino acid in the medium. Media containing individual amino acids, also stimulated varied growth depending upon amino acid concentration and medium pH. Maximum dry weight and conidial production occurred around pH 6.
Growth on mixtures of amino acids suggested that the fungus used amino acids as individual medium components and not as a single quantity of nitrogen. Any medium containing asparagine stimulated a large conidial production. Dry weight production showed the least variation.
All amino acids added to sugar maple sap stimulated dry weight production. Asparagine, glutamine, proline and citrulline stimulated conidial production, while allantoic acid did not.
CDA modified in sugar content induced no variation in dry weight production. Conidial production was stimulated when glucose or a glucose and sucrose combination were in a medium; fructose induced the opposite effect.
Tension applied to an inoculated liquid medium stimulated conidial production of the fungus within the medium.
Issue Date:1983
Description:91 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983.
Other Identifier(s):(UMI)AAI8324540
Date Available in IDEALS:2014-12-15
Date Deposited:1983

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