CONSTRUCTION OF A CONTIG AROUND A VIRUS RESISTANCE GENE IN THE COMMON BEAN.

¹ Department of Horticultural Sciences and Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL 32611 USA

² Department of Agronomy and Genetics Program, Purdue University, West Lafayette, IN 47907 USA

We have targeted the I gene of Phaseolus vulgaris for positional cloning. The I gene confers resistance to a group of strains of bean common mosaic virus and eight other distinct potyviruses. In addition, the action of this gene can be modified by a combination of four recessive resistance genes in a strain specific manner. We are using a P. vulgaris BAC library, constructed in Sally Mackenzie's lab at Purdue University, for the assembly of a contig around our target gene. The library contains five genome equivalents, and the average insert size has been estimated at 100 Kb. We are using the termini of the contig as probes to measure the recombination frequency within the physical length of the contig, and between the contig and the target gene. We are using a large F₂ family (n>1000) for this purpose. This information provides an estimate of the relationship between Kb and cM in that region of the genome, and by extension the physical distance between the contig and the I gene.