Bacterial, fungal, and viral disease resistance loci mapped in a recombinant inbred common bean population ('Dorado'/XAN 176)

Understanding the genomic associations among disease resistance loci will f acilitate breeding of multiple disease resistant cultivars, We constructed a genetic Linkage map in common bean (Phaseolus vulgaris L,) containing six genes and nine quantitative trait loci (QTL) comprising resistance to one bacterial, three fungal, and two viral pathogens of bean,bean, The mapping population consisted of 79 F-5:7 recombinant inbred Lines (RILs) derived fr om a 'Dorado'/XAN 176 hybridization, There were 147 randomly amplified poly morphic DNA (RAPD) markers, two sequence characterized amplified region (SC AR) markers, one intersimple sequence repeat (ISSR) marker, two seedcoat co lor genes R and V, the Asp gene conditioning seed brilliance, and two rust [Uromyces appendiculatus var, appendiculatus (Pers,:Pers) Unger] resistance genes: one conditioning resistance to Races 53 and 53 and the other condit ioning resistance to Race 108, These markers mapped across eleven Linkage g roups, one linked triad, and seven linked pairs for an overall map length o f 930 cM (Kosambi). Genes conditioning resistance to anthracnose (Co-2) [Co lletotrichum lindemuthianum (Sacc, and Magnus) Lams.-Scrib.], bean rust (Ur -5). and bean common mosaic virus (I and bc-3) (BCR IV) did not segregate i n this population, but were mapped by inference using linked RAPD and SCAR markers identified in other populations. Nine previously reported quantitat ive trait loci (QTL) conditioning resistance to a variety of pathogens incl uding common bacterial blight [Xanthomonas campestris pv,phaseoli (Smith) D ye], ashy stem blight [Macrophornina phaseolina (Tassi) Gold,], and bean go lden mosaic virus (BGMV), were located across four linkage groups. Linkage among QTL for resistance to ashy stem blight, BGMV, and common bacterial bl ight on linkage group B7 and ashy stem blight, BGMV, and rust resistance lo ci on B4 will complicate breeding for combined resistance to all four patho gens in this population.