MOLECULAR MARKERS ASSOCIATED WITH PLANT ARCHITECTURE AND RESISTANCE TO COMMON BLIGHT, WEB BLIGHT, AND RUST IN COMMON BEANS

Random amplified polymorphic DNA (RAPD) markers were used to construct a partial linkage map in a recombinant inbred population derived from the common bean (Phaseolus vulgaris L.) cross BAC 6 x HT 7719 for stu dying the genetics of disease resistance in common bean. The linkage m ap spanned 545 cM and included 75 of 84 markers used in this study, Th e population of 128 recombinant inbred lines was evaluated for resista nce to common bacterial blight, foliar resistance to web blight [WB; T hanatephorus cucumeris (Frank) Donk], and resistance to rust [Uromyces appendiculatus var, appendiculatus (Pers.:Pers) Unger]. Common bacter ial blight [CBB; Xanthomonas campestris pv. phaseoli (Smith) Dye] resi stance was evaluated for CBB strain Epif-IV in later-developed trifoli olate leaves and for CBB strain EK-11 in seeds, first trifoliolate lea ves, later-developed trifoliolate leaves, and pods. In addition,lines were rated for plant uprightness and branch density, Two to six marker s accounted for 14% to 34% of the phenotypic variation for each trait, Significant marker locus-trait associations were found for 14 mapped loci and 7 of the 9 unmapped markers, The distribution of detected QTL appeared to be nonrandom with most significant markers associated wit h more than one trait of closely linked to markers significantly assoc iated with variation for a different trait, One marker, BC409(1250), w as significantly associated with WE resistance, resistance for CBB str ain Epif-IV in later-developed trifoliolate leaves, and resistance for CBB strain EK-11 in first trifoliolate leaves, later-developed trifol iolate leaves, and pods. A rust resistance gene was mapped in an inter val 14.6 chi from RAPD marker H19(1050) and 12.5 cM from marker AJ16(2 50).