- Fruits: apples, pears
- Pest Management: genetic resistance
Fire blight, caused by the bacterium Erwinia amylovora, is a costly disease to apple and pear growers in the Northeast US. While management is achieved via antibiotics, genetic resistance represents a more sustainable strategy. The E. amylovora secreted protein HrpN, an essential virulence factor, triggers an unusually strong defense response in tobacco (Nicotiana tabacum) that suggests a resistance (R) gene-mediated recognition pathway. This project seeks to uncover the genetic basis of HrpN recognition in tobacco for potential transfer to apple or pear to confer HrpN recognition and fire blight resistance. A preliminary survey of tobacco germplasm identified accessions that are unresponsive to HrpN, suggesting a mutation in one or more genes responsible for HrpN recognition. To elucidate the heritability of this phenotype, three accessions unresponsive to HrpN will be crossed with a HrpN-responsive accession to generate segregating F2 populations. After phenotyping, a bulked segregant analysis will be performed on HrpN-responsive and HrpN-unresponsive pools of individuals to detect genetic variations strongly associated with the trait. This research will produce candidate resistance genes that will be evaluated through additional lab and field studies beyond the termination of the grant. Identification of genes involved in HrpN recognition would advance the fire blight field, as few genetic sources of fire blight resistance have been characterized. Communication of results to regional and international plant pathology researchers will be achieved through conference attendance and journal publications. Local tree fruit producers will also be engaged through an on-farm outreach event at the end of the project period.
Project objectives from proposal:
Objective 1: Determine the inheritance patterns of the HrpN-induced HR in one or more mapping populations of tobacco.
Objective 2: Identify one or more candidate resistance genes in a tobacco mapping population by performing a bulked segregant analysis.