Poster: Late and Moved Abstracts

Abs # 1025: Construction of BAC Contigs Containing Barley Resistance Gene Analogs

Presenter:	Mammadov, Jafar A, jmammado@vt.edu
Authors	Mammadov, Jafar A (A)   Biyashev, Ruslan M (A)   Saghai Maroof, Mohammad A. (A)
Affiliations:	(A): Department of Crop and Soil Environmental Sciences, Virginia Tech

The majority of the cloned plant disease resistance genes (R) encode a putative nucleotide binding site (NBS) domain and leucine-rich repeat (LRR) region. Barley resistance gene analogs (RGAs) used in this study were previously developed and genetically mapped in our laboratory. Degenerate primers designed from the conserved motifs of the NBS in tobacco N and Arabidopsis RPS2 genes were used to amplify genomic DNA from three barley cultivars. These RGAs genetically mapped onto all barley chromosomes but 5H. In this study, we used 25 barley RGAs to screen the 6.3X barley cv. Morex BAC library to identify BACs containing members of RGA families and to construct BAC contigs for the physical mapping of the RGAs. After fingerprinting analysis, 6 contigs were developed, incorporating 58 BAC clones. The number of RGAs per contig ranged from 1 to 3 with an average of 1.8 RGAs. BAC contig size ranged from 180 to 280 Kb with an average of 202 Kb. A minimum of one RGA per 190 kb and maximum of one RGA per 53.3 kb were observed among the contigs. Almost all RGAs were previously mapped in the vicinity of known R genes conferring resistance to economically important diseases of barley, including Fusarium head blight, kernel discoloration, net blotch, leaf rust, barley yellow dwarf virus, cereal cyst nematode, stripe rust and powdery mildew. The BAC clones identified in this study can potentially harbor R genes and therefore are useful for the cloning of barley disease resistance genes.