Biological Control of Lettuce Drop Caused by Sclerotinia Spp. Using Coniothyrium Minitans and Elucidation of Biochemical Interactions During Mycoparasitism

Persistent Link:
http://hdl.handle.net/10150/195487
Title:
Biological Control of Lettuce Drop Caused by Sclerotinia Spp. Using Coniothyrium Minitans and Elucidation of Biochemical Interactions During Mycoparasitism
Author:
Chitrampalam, Periasamy
Issue Date:
2009
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
This work encompasses studies on the development of biocontrol strategies to manage the disease lettuce drop, caused by the fungi Sclerotinia sclerotiorum and S. minor, using the mycoparasitic fungus Coniothyrium minitans, and to better understand interactions during mycoparasitism at the biochemical level. Results from field experiments revealed that two applications of C. minitans at manufacturer recommended rates significantly reduced the incidence of lettuce drop caused by S. sclerotiorum but not by S. minor. Applications of other biocontrol products tested did not significantly reduce disease incidence caused by either pathogen. Sclerotium population studies revealed that soil populations of S. sclerotiorum in lettuce production fields ranged from 0.08 to 2.9 sclerotia/100g of soil and were generally aggregated in their distribution. Continued field studies revealed that there was no significant effect of irrigation (sprinkler vs furrow) on either the impact of sclerotium density or the efficacy of C. minitans. Studies on the evaluation of different application rates of Contans against S. minor revealed that two applications of Contans at 5 X manufactures recommended rates significantly reduced the disease incidence. Examination of sclerotial exudates of Sclerotinia spp. revealed that crude exudates from both Sclerotinia spp. stimulated C. minitans spore germination and the stimulation was due to compounds within the polar fraction. Studies on the role of lectin-carbohydrate binding during fungal-mycoparasite interactions revealed that many plant lectins as well as crude proteins extracted from sclerotia of either Sclerotinia spp. induced agglutination of C. minitans spores in vitro. Spore germination of C. minitans stimulated by sclerotial exudates of either Sclerotinia spp. was significantly inhibited in the presence of the lectin Con A but not other plant lectins. In vitro studies on the directional growth of C. minitans preceding mycoparasitism revealed the involvement of G proteins for optimal response of C. minitans toward Sclerotinia stimulus.
Type:
text; Electronic Dissertation
Keywords:
Biocontrol; Coniothyrium; Lettuce Drop; Sclerotinia
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Plant Pathology; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Pryor, Barry M.
Committee Chair:
Pryor, Barry M.

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleBiological Control of Lettuce Drop Caused by Sclerotinia Spp. Using Coniothyrium Minitans and Elucidation of Biochemical Interactions During Mycoparasitismen_US
dc.creatorChitrampalam, Periasamyen_US
dc.contributor.authorChitrampalam, Periasamyen_US
dc.date.issued2009en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThis work encompasses studies on the development of biocontrol strategies to manage the disease lettuce drop, caused by the fungi Sclerotinia sclerotiorum and S. minor, using the mycoparasitic fungus Coniothyrium minitans, and to better understand interactions during mycoparasitism at the biochemical level. Results from field experiments revealed that two applications of C. minitans at manufacturer recommended rates significantly reduced the incidence of lettuce drop caused by S. sclerotiorum but not by S. minor. Applications of other biocontrol products tested did not significantly reduce disease incidence caused by either pathogen. Sclerotium population studies revealed that soil populations of S. sclerotiorum in lettuce production fields ranged from 0.08 to 2.9 sclerotia/100g of soil and were generally aggregated in their distribution. Continued field studies revealed that there was no significant effect of irrigation (sprinkler vs furrow) on either the impact of sclerotium density or the efficacy of C. minitans. Studies on the evaluation of different application rates of Contans against S. minor revealed that two applications of Contans at 5 X manufactures recommended rates significantly reduced the disease incidence. Examination of sclerotial exudates of Sclerotinia spp. revealed that crude exudates from both Sclerotinia spp. stimulated C. minitans spore germination and the stimulation was due to compounds within the polar fraction. Studies on the role of lectin-carbohydrate binding during fungal-mycoparasite interactions revealed that many plant lectins as well as crude proteins extracted from sclerotia of either Sclerotinia spp. induced agglutination of C. minitans spores in vitro. Spore germination of C. minitans stimulated by sclerotial exudates of either Sclerotinia spp. was significantly inhibited in the presence of the lectin Con A but not other plant lectins. In vitro studies on the directional growth of C. minitans preceding mycoparasitism revealed the involvement of G proteins for optimal response of C. minitans toward Sclerotinia stimulus.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectBiocontrolen_US
dc.subjectConiothyriumen_US
dc.subjectLettuce Dropen_US
dc.subjectSclerotiniaen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplinePlant Pathologyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorPryor, Barry M.en_US
dc.contributor.chairPryor, Barry M.en_US
dc.contributor.committeememberPierson, Elizabeth A.en_US
dc.contributor.committeememberCotty, Peter J.en_US
dc.contributor.committeememberSchumaker, Karen S.en_US
dc.identifier.proquest10529en_US
dc.identifier.oclc659752263en_US
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