Dissertation
PHENOTYPIC SCREENING OF SWEET CHERRY (PRUNUS AVIUM L.) GERMPLASM AND IDENTIFICATION OF QUANTITATIVE TRAIT LOCI ASSOCIATED WITH BACTERIAL CANKER DISEASE
Doctor of Philosophy (PhD), Washington State University
01/2016
Handle:
https://hdl.handle.net/2376/117567
Abstract
PHENOTYPIC SCREENING OF SWEET CHERRY (PRUNUS AVIUM L.) GERMPLASM AND IDENTIFICATION OF QUANTITATIVE
TRAIT LOCI (QTL) UNDERLYING BACTERIAL
CANKER DISEASE
Abstract
by Josephine Udodirim Mgbechi-Ezeri, Ph.D.
Washington State University
May 2016
Chair: Nnadozie Oraguzie
Bacterial canker disease caused by Pseudomonas syringae pv. syringae is an economically important disease of sweet cherry in the pacific northwest (PNW) of USA and in other regions of the world. This study was designed to screen Washington State University’s sweet cherry germplasm, to identify quantitative trait loci (QTL) associated with disease responses, and to identify and characterize pathogens associated with canker diseases of sweet cherry in the PNW.
The effects of leaf age, assay method (detached versus attached) and inoculum concentrations on disease response were evaluated. Detached young leaves showed increased disease severity while inoculum concentration of 1x108 cfu/ml was ideal for infection. This protocol was used to phenotype ~500 sweet cherry germplasm for bacterial canker disease responses.
QTL analysis was performed in FlexQTL™ using phenotypic data from 2013 and 2014. QTLs associated with bacterial canker disease responses were identified on linkage groups (LG) 2, 3, 5, 7 and 8. The QTL, BC_LG5_1, common between years that accounted for ~15% of the phenotypic variation in disease response has been targeted for use in developing a marker assisted breeding strategy for bacterial canker in sweet cherry.
Five commercial cultivars, six advanced selections, and ‘PMR-1’, showing high to moderate responses to bacterial canker disease were evaluated in the greenhouse. Disease response in the commercial cultivars was high but low to moderate in the advanced selections and ‘PMR-1’. The advanced selections could serve as parents for resistance breeding.
Biochemical and molecular characterization of bacterial isolates from infected sweet cherries in the PNW showed low occurrence of Pseudomonas spp (10%) with high diversity among isolates. An undescribed pathogenic Pseudomonas species was also identified. A yeast-like fungus Collophora paarla was isolated for the first time from cankerous sweet cherry tissues. Additionally, the pathogenicity of Aureobasidium spp and C. paarla was established on 5 months old sweet cherry seedling and leaves. This information will expand knowledge on other possible pathogens causing canker symptoms in sweet cherry.
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Details
- Title
- PHENOTYPIC SCREENING OF SWEET CHERRY (PRUNUS AVIUM L.) GERMPLASM AND IDENTIFICATION OF QUANTITATIVE TRAIT LOCI ASSOCIATED WITH BACTERIAL CANKER DISEASE
- Creators
- Josephine Udodirim Mgbechi-Ezeri
- Contributors
- Nnadozie C Oraguzie (Advisor)Amit Dhingra (Committee Member)Kenneth Johnson (Committee Member)Lyndon Porter (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Horticulture, Department of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 275
- Identifiers
- 99900581522201842
- Language
- English
- Resource Type
- Dissertation