Characterization of Resistance to Respiration Inhibitor Fungicides in Populations of Tangerine-Infecting Alternaria alternata

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Material Information

Title:
Characterization of Resistance to Respiration Inhibitor Fungicides in Populations of Tangerine-Infecting Alternaria alternata
Physical Description:
1 online resource (12 p.)
Language:
english
Creator:
Vega Jimenez, Byron Patricio
Publisher:
University of Florida
Place of Publication:
Gainesville, Fla.
Publication Date:

Thesis/Dissertation Information

Degree:
Doctorate ( Ph.D.)
Degree Grantor:
University of Florida
Degree Disciplines:
Plant Pathology
Committee Chair:
DEWDNEY,MEGAN M
Committee Co-Chair:
HARMON,PHIL F
Committee Members:
PERES,NATALIA A R
ROGERS,MICHAEL E

Subjects

Subjects / Keywords:
baseline -- fitness -- fungicides -- qoi -- resazurin -- resistance -- sdhi
Plant Pathology -- Dissertations, Academic -- UF
Genre:
Plant Pathology thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract:
Chemical control of Alternaria brown spot (ABS), caused by Alternaria alternata, is based upon the timely application of site-specific fungicides,many of which are vulnerable to the development of fungicide resistance.Quinone outside inhibitors (QoIs) have been used for more than 10 years for ABScontrol, but in 2008 the first case of QoI resistance was detected in Floridaincreasing the concern in the tangerine industry. The purpose of this researchwas to characterize morphologically and molecularly resistance to QoI andsuccinate dehydrogenase inhibitor (SDHI) fungicides in tangerine-infecting A.alternata populations. A rapid microtiter bioassay, based on the colorimetricchanges of resazurin dye, was developed to evaluate the sensitivity of A.alternata to those respirationinhibitor fungicides. From 2008 to 2012, 817 monoconidial isolates of A.alternata from 46 citrus orchardswere examined for sensitivity to QoIs (azoxystrobin and pyraclostrobin). Of theisolates, 57.6% were resistant to both fungicides. The proportion of resistantisolates differed significantly among cultivars and with QoI applicationfrequency. Moreover, the molecular basis for QoI resistance was determined fora subset of 235 isolates. All resistant isolates showed the point mutationG143A and were further classified as profile I and profile II, based on thepresence of one or two introns, respectively. Phenotypic stability, fitness components, and the ability to cause disease ofQoI-resistant isolates were also studied. Great variability in fitnesscomponents was observed among isolates within the same sensitivity group.Results suggest that QoI resistance in A. alternata was stable in the absence of QoI selection pressure and that theresistant development did not affect the fitness of resistant isolates. Furthermore,the effect of boscalid (SDHI) on multiple physiological stages of fungaldevelopment was established. Sensitivity distribution of 419 A. alternara isolates was tested using isolates neverexposed to boscalid. The molecular characterization of the succinatedehydrogenase (SDH) genes was also determined by cloning and sequencing the SdhB,SdhC, and SdhD genes. Sequencecomparisons of the SDH complex revealed the presence of mutations in 93% ofisolates evaluated. Overall, results from this study will provide bases toimprove disease management programs against ABS in Florida.
General Note:
In the series University of Florida Digital Collections.
General Note:
Includes vita.
Bibliography:
Includes bibliographical references.
Source of Description:
Description based on online resource; title from PDF title page.
Source of Description:
This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility:
by Byron Patricio Vega Jimenez.
Thesis:
Thesis (Ph.D.)--University of Florida, 2014.
Local:
Adviser: DEWDNEY,MEGAN M.
Local:
Co-adviser: HARMON,PHIL F.
Electronic Access:
RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2014-11-30

Record Information

Source Institution:
UFRGP
Rights Management:
Applicable rights reserved.
Classification:
lcc - LD1780 2014
System ID:
UFE0046469:00001