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Honglin Chen, Shawn A. Mehlenbacher, and David C. Smith

’, displayed no symptoms of EFB after greenhouse inoculations ( Lunde et al., 2000 ). Complete resistance has also been detected in numerous accessions of Corylus species and interspecific hybrids ( Coyne et al., 1998 ; Lunde et al., 2000 ). The fungus A

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Daniel H. Ronis, Anson E. Thompson, David A. Dierig, and Earl R. Johnson

Five interspecific Cuphea hybrids were examined for isozyme banding patterns. In three of the five hybrids (C. viscosissima × C. lutea, C. ignea × C. angustifolia, and C. lanceolata × C. viscosissima), F1 plants could be distinguished from either parental species. Phosphoglucomutase and 6-phosphogluconic dehydrogenase enzyme stains produced distinct F1 band patterns for all three hybrids. Phosphoglucose isomerase and shikimate dehydrogenase enzyme stains produced distinct F1 band patterns for C. viscosissima × C. lutea and C. lanceolata× C. viscosissima, respectively. For the C. lanceolata × C. viscosissima hybrid. the banding patterns were used to identify 32 selfs among 161 putative F1 plants.

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Mei Guo, David A. Lightfoot, Machteld C. Mok, and David W. S. Mok

Interspecific hybridization between Phaseolus vulgaris and P. coccineus results in mature seeds or abnormal embryo formation depending on the direction of the cross. In addition, differential fertility and reversion to parental types occur in later progeny populations, accompanied by recurrence of various embryo types. Normal and abnormal embryos exhibited isozyme patterns resembling P. vulgaris and P. coccineus parents respectively, suggesting that developmental abnormalities may be associated with specific combinations of parental genes. RFLP between parental species was examined and probes were selected for analyses of F2 populations. Differential transmission of alleles occurred for some RFLP markers. Statistical analyses were applied to detect possible association between probes and abnormal developmental events. The high incidence of interspecific polymorphism will also facilitate the construction of a linkage map in Phaseolus.

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Mei Guo, David A. Lightfoot, Machteld C. Mok, and David W. S. Mok

Interspecific hybridization between Phaseolus vulgaris and P. coccineus results in mature seeds or abnormal embryo formation depending on the direction of the cross. In addition, differential fertility and reversion to parental types occur in later progeny populations, accompanied by recurrence of various embryo types. Normal and abnormal embryos exhibited isozyme patterns resembling P. vulgaris and P. coccineus parents respectively, suggesting that developmental abnormalities may be associated with specific combinations of parental genes. RFLP between parental species was examined and probes were selected for analyses of F2 populations. Differential transmission of alleles occurred for some RFLP markers. Statistical analyses were applied to detect possible association between probes and abnormal developmental events. The high incidence of interspecific polymorphism will also facilitate the construction of a linkage map in Phaseolus.

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J.A. Mortensen, J.W. Harris, D.L. Hopkins, and P.C. Andersen

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C. L. Gupton, J. M. Spiers, and A. D. Draper

Eight clones with various Vaccinium species in their background were evaluated to determine their potential for improving fruit characteristics in the southern highbush blueberry. One clone was crossed with each of the others to produce seven sets of progenies which were evaluated with the parent clones. Heritability estimates were computed as the regression of progeny on parental means for each character. The progenies ranged from small to average berry size and weight, were above average for picking scar, and were generally less than average for color, firmness, and flavor. Mean of progenies was not significantly different from the parental mean for any character. Very high (0.45-0.85) heritability estimates were found for each character except berry firmness (0.22). These results suggest that considerable improvement in each character except possibly berry firmness should result from phenotypic recurrent selection in a broad based population involving these parents.

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Andrew Riseman, V.A. Sumanasinghe, Douglas Justice, and Richard Craig

We propose the name Exacum Styer Group for an interspecific population derived from several Sri Lankan Exacum taxa. Confirmation of hybrid status was determined by the appearance of either unique trait combinations or intermediate forms of traits originally represented by individual native taxa. Through 12 sexual generations, the proposed cultivar-group continues to exhibit these unique traits and now forms a cohesive fertile population.

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Timothy M. Spann, Jeffrey G. Williamson, and Rebecca L. Darnell

Experiments were conducted with V. darrowi and two cultivars of southern highbush blueberry, `Sharpblue' and `Misty,' to test whether V. darrowi and cultivars derived from it are photoperiodic with respect to flower bud initiation. Plants of each cultivar were grown under three different photoperiod treatments [long days (LD) = 16-hour photoperiod; short days (SD) = 8-hour photoperiod; and short days + night interrupt (SD-NI) = 8-hour photoperiod with 1-hour night interrupt] at constant 21 °C for 8 weeks. Vegetative growth was greatest in the LD plants of both cultivars. Flower bud initiation occurred only in the SD treatments, and the lack of flower bud initiation in the SD-NI treatment indicates that flower bud initiation is a phytochrome mediated response in Vaccinium. Previously initiated flower buds on the V. darrowi plants developed and bloomed during the LD treatment, but bloom did not occur in the SD and SD-NI treatment plants until after those plants were moved to LD. These data indicate that flower bud initiation in both V. darrowi and southern highbush blueberry is photoperiodically sensitive, and is promoted by short days, while flower bud development is enhanced under long days.

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Paul W. Bosland and Jit B. Baral

In replicated trials at Las Cruces, N.M., the Scoville heat units (SHUs) of ‘Bhut Jolokia’, a chile pepper from Assam, India, reached one million SHUs. Morphologic characters revealed that ‘Bhut Jolokia’ is a Capsicum chinense Jacq. cultivar. Molecular analysis with randomly amplified polymorphic DNA markers confirmed the species identification and, interestingly, revealed that there may have been genetic introgression from Capsicum frutescens L. into ‘Bhut Jolokia’.

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Richard W. Hartmann

F3 seeds from a cross of P. erosus (indeterminate, daylength sensitive) X P. ahipa (determinate, daylength insensitive) were received from M. Sorensen of the Royal Veterinary and Agricultural University in Copenhagen, Denmark and sown in Hawaii in April, 1989 to increase the seed. The F4 seed were planted in March, 1990 and in October, 1990 (the normal time). All F4 progeny included both bush and vine plants in the summer planting, with more bush plants in the progeny of F3 bushes than vines. Likewise, the progeny of earlier-flowering F3 plants had a higher percentage of plants in flower in June than progeny of later-flowering ones. Root sizes and shapes were variable. The F4 progenies of the lines with the highest percentage of bushes and early-flowering plants were regrown in the summer of 1991 and selected for summer-flowering bush plants with acceptable root size. The selections were then grown in the winter of 1991 to test for performance during the normal growing season.