Genetic markers linked with quantitative trait loci (QTL) may enable indirect selection of complex disease resistance. Construction of separate linkage maps to identify QTL for each complex disease resistance trait of common bean (Phaseolus vulgaris L.) is unfeasible, however. We investigated whether selective mapping could be used to hasten identification of random amplified polymorphic DNA (RAPD) associated with QTL conditioning bean golden mosaic virus (BGMV) or common bacterial blight (CBB) resistance. The mapping population (‘Dorado’ × XAN 176) consisted of 79 F5:7 recombinant inbred lines. A bulked segregant analysis (BSA) of as few as three individuals and selective genotyping was used. The 101 RAPDs identified between the parents were tested across resistant vs. susceptible bulks for BGMV reaction, combined greenhouse (leaf) and field reactions to CBB, and pod (greenhouse) reaction to CBB. Fourteen of 22 RAPDs selectively mapped because they cosegregated among lines within bulks, were linked with seven of the nine QTL conditioning resistance as identified by QTL mapping using all 101 RAPDs. The two QTL not identified by this approach had minor effects. BSA and selective genotyping required only about one‐third the cost and labor of completely classifying the whole population with each marker and was similarly effective for identifying RAPD markers associated with major‐effect QTL that condition disease resistance in common bean. Two‐locus models (R2), for select environments, explained 60% of the phenotypic variation in BGMV reaction, and 65, 58, and 46% of the phenotypic variation in greenhouse‐leaf, ‐pod, and field reactions to CBB. Repulsion linkages between QTL for BGMV and CBB may complicate the combination of resistance alleles for these two traits.

Each year, large volumes of ornamental and food plant propagative stock are imported into the North America; occasionally, Ralstonia solanacearum is found systemically infecting this plant material. In this study, 107 new R. solanacearum strains were collected over a 10-year period from imported propagative stock and compared with 32 previously characterized R. solanacearum strains using repetitive polymerase chain reaction (rep-PCR) element (BOX, ERIC, and REP) primers. Additional strain comparisons were made by sequencing the endoglucanase and the cytochrome b561 genes. Using rep-PCR primers, populations could be distinguished by biovar and, to a limited extent, country of origin and original host. Similarity coefficients among rep-PCR clusters within biovars were relatively low in many cases, indicating that disease outbreaks over time may have been caused by different clonal populations. Similar population differentiations of R. solanacearum were obtained when comparing strain sequences using either the endoglucanase or cytochrome b561 genes. We found that most of the new biovar 1 strains of R. solanacearum entering the United States were genetically distinct from the biovar 1 strains currently found infecting vegetable production. These introduced biovar 1 strains also had a broader host range and could infect not only tomato, tobacco, and potato but also anthurium and pothos and cause symptoms on banana. All introductions into North America of race 3, biovar 2 strains in the last few years have been linked to geranium production and appeared to be clonal.

‘Verano’, Reg. No. CV‐282, PI 653706, a multiple disease resistant white bean (Phaseolus vulgaris L.) cultivar adapted to the humid tropics, was developed and released in 2007 cooperatively by the University of Puerto Rico Agricultural Experiment Station and the USDA‐ARS. Verano has tolerance to high temperature and resistance to Bean golden yellow mosaic virus, a whitefly [Bemisia tabaci (Gennadius)]‐transmitted begomovirus, Bean common mosaic virus, and common bacterial blight [caused by Xanthomonas axonopodis pv. phaseoli (Smith) Dye]. The release and adoption of a high temperature–tolerant cultivar such as Verano will improve yield and seed quality of green‐shelled beans produced in Puerto Rico. Verano possesses traits that may be useful to breeding programs where high temperature, viral diseases, and common bacterial blight limit bean production.

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