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Geunhwa Jung, Dermot P. Coyne, E. Arnaud-Santana, James Bokosi, Shawn M. Kaeppler, Paul W. Skroch, and James Nienhuis

Common bacterial blight(CBB) and rust diseases, incited by the bacterial pathogen Xanthomonas campestris pv. phaseoli (Smith) Dye (Xcp) and Uromyces appendiculatus, respectively, are important diseases of common beans (Phaseolus vulgaris L.). The objectives were to construct a molecular linkage map, to locate CBB resistances, rust resistances and leaf pubescence using RAPDs. Sixteen linkage groups with 22 unassigned markers were identified. 178 RAPD markers and 8 morphological markers were mapped in a Population of 70 RI lines. Regression analysis and interval mapping using MAPMAKER/QTL were used to identify genomic regions involved in the genetic control of the traits. One, two, and three putative QTLs were identified for seed, pod and leaf reactions. These regions accounted for 18%, 25%, and 35% of the phenotypic variation in CBB resistance. A chromosome region on linkage group 1 carried factors influencing all three traits. Rust resistance genes controlling the reactions on the primary and on the 4th trifoliolate leaves (adult plant resistance) were located in linkage group 16. The genes for abaxial leaf pubescence was located on linkage group 9.

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Geunhwa Jung, Dermot P. Coyne, Paul W. Skroch, James Nienhuis, E. Arnaud-Santana, James Bokosi, H.M. Ariyarathne, James R. Steadman, James S. Beaver, and Shawn M. Kaeppler

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 × HT 7719 for studying the genetics of disease resistance in common bean. The linkage map spanned 545 cM and included 75 of 84 markers used in this study. The population of 128 recombinant inbred lines was evaluated for resistance to common bacterial blight, foliar resistance to web blight [WB; Thanatephorus cucumeris (Frank) Donk], and resistance to rust [Uromyces appendiculatus var. appendiculatus (Pers.:Pers) Unger]. Common bacterial blight [CBB; Xanthomonas campestris pv. phaseoli (Smith) Dye] resistance was evaluated for CBB strain Epif-IV in later-developed trifoliolate leaves and for CBB strain EK-11 in seeds, first trifoliolate leaves, later-developed trifoliolate leaves, and pods. In addition, lines were rated for plant uprightness and branch density. Two to six markers accounted for 14% to 34% of the phenotypic variation for each trait. Significant marker locustrait 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 with more than one trait or closely linked to markers significantly associated with variation for a different trait. One marker, BC4091250, was significantly associated with WB resistance, resistance for CBB strain Epif-IV in later-developed trifoliolate leaves, and resistance for CBB strain EK-11 in first trifoliolate leaves, later-developed trifoliolate leaves, and pods. A rust resistance gene was mapped in an interval 14.6 cM from RAPD marker H191050 and 12.5 cM from marker AJ16250.

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Geunhwa Jung, Paul W. Skroch, Dermot P. Coyne, James Nienhuis, E. Arnaud-Santana, H.M. Ariyarathne, Shawn M. Kaeppler, and Mark J. Bassett

Randomly amplified polymorphic DNA (RAPD) molecular markers were used to construct a partial genetic linkage map in a recombinant inbred population derived from the common bean (Phaseolus vulgaris L.) cross PC-50 × XAN-159 for studying the genetics of bacterial disease resistance in common bean. The linkage map spanned 426 cM and included 168 RAPD markers and 2 classical markers with 11 unassigned markers. The seventy recombinant inbred lines were evaluated for resistance to two strains of common bacterial blight [Xanthomonas campestris pv. phaseoli (Smith) Dye] (Xcp). Common bacterial blight (CBB) resistance was evaluated for Xcp strain EK-11 in later-developed trifoliolate leaves and for Xcp strains, DR-7 and EK-11, in first trifoliolate leaves, seeds, and pods. One to four quantitative trait loci (QTLs) accounted for 18% to 53% of the phenotypic variation for traits. Most significant effects for CBB resistance were associated with one chromosomal region on linkage group 5 and with two regions on linkage group 1, of the partial linkage map. The chromosomal region (a 13-cM interval) in linkage group 5 was significantly associated with resistance to Xcp strains DR-7 and EK-11 in leaves, pods, and seeds. The regions in linkage group 1 were also significantly associated with resistance to both Xcp strains in more than one plant organ. In addition, a seedcoat pattern gene (C) and a flower color gene (vlae) were mapped in linkage groups 1 and 5, respectively, of the partial linkage map. The V locus was found to be linked to a QTL with a major effect on CBB resistance.