Date of Award

3-12-2020

Publication Type

Doctoral Thesis

Degree Name

Ph.D.

Department

Biological Sciences

Keywords

Genomics, Introgression, Phaseolus

Supervisor

William Crosby

Rights

info:eu-repo/semantics/openAccess

Abstract

Phaseolus vulgaris is a major food crop grown and consumed around the world. A new world vegetable, the common bean underwent two separate domestication events, both pre-Columbus. These events generated two different land races, the Mesoamerican and Andean, named for the area where the domestication took place. Since the initial domestications the land races have been generally evenly cultivated, but despite its popularity the common bean has only very recently been fully sequenced. One of the issues faced by bean growers worldwide is Common Bacterial Blight (CBB). A disease caused by Xanthomonas axonopodis, CBB causes crop loses ranging from 20–40% every year but does not affect all species within Phaseolus evenly; P. acutifolius, for example, shows an innate resistance to CBB. To leverage this advantage, researchers at the University of Guelph, in partnership with the Ontario Agricultural College, developed a cultivar of Mesoamerican P. vulgaris that was introgressed with PI440795, a P. acutifolius accession, and backcrossed repeatedly with several other Mesoamerican P. vulgaris accessions to generate ‘OAC-Rex’, a plant that displays the crop-desired traits of P. vulgaris and the disease resistance traits of P. acutifolius. Genetic introgression is the process of crossing distantly related organisms followed by repeated backcrossing, resulting in a viable offspring that displays characteristics of each parent. Though rarely occurring, it can be observed in both plants and animals and is often exploited in a crop development context to generate new cultivars. Unfortunately, though regularly observed, introgression has been followed on a predominantly phenotypic level, usually many generations after the event, and as such molecular aspects of this phenomenon are largely unknown.By studying OAC-Rex, PI440795, and G-19833 (an Andean cultivar whose whole-genome has been published) introgression was examined directly and a method for the detection of regions within the introgressed genome uniquely donated from either parent

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