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Title: Molecular detection and quantification of the pea footrot disease pathogen (Nectria haematococca) in agricultural soils : a potential model for disease prediction
Author: Etebu, Ebimieowei
ISNI:       0000 0001 3449 5353
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2008
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In this research, PCR-based detection assays were developed to detect and quantify three N. haematococca pathogenicity genes (PDA, PEP3 and PEP5) both from isolates and DNA extracted from agricultural fields with footrot history. Denaturing gradient gel electrophoresis (DGGE), gene cloning and sequencing assays were used to explore the diversity of these genes in agricultural soils. The applicability of using quantitative (real-time) PCR to quantify these genes in infected soils was validated. Furthermore, biotic and abiotic factors that interact to cause pea footrot disease in soil were also studied. Results showed that the PDAH allele of the PDA gene, responsible for rapid demethylation of the phytoalexin pisatin, together with PEP3 and PEP5 genes promotes maximal footrot disease in peas. DGGE results showed diversity amongst PDA and PEP5 partial gene sequences amplified from agricultural soil-DNA. Partial PEP3 gene sequences showed no diversity. There was a positive correlation between numbers of pathogenic N. haematococca spores and numbers of pea pathogenicity genes in soil. Pea pathogenicity gene numbers of up to 100 per gram of soil constituted a threshold number for pea footrot infection; potentially capable of causing footrot disease of economic proportion. A disease model that included total phosphate, carbon and ammonium-nitrogen was identified with stepwise regression analysis (R² = 0.42). The PCR-based techniques developed herein are viable and reliable alternatives to culture-based assays for accurate detection and quantification of pathogenic N. haematococca in soils. They offer the opportunity for quantitative prediction of pea footrot infections in agricultural soils prior to cultivation.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available