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Kathleen Demchak

July 2008 < http://www.fruitgrowersnews.com/pages/2000/issue00_07/issue00july_bleacher_berry.html >. Privé, J.P. Allain, N. 2000 Wind reduces growth and yield but not net leaf photosynthesis of primocane-fruiting red raspberries ( Rubus idaeus L.) in

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Rengong Meng and Chad Finn

Nuclear DNA flow cytometry was used to differentiate ploidy level and determine nuclear DNA content in Rubus. Nuclei suspensions were prepared from leaf discs of young leaves following published protocols with modifications. DNA was stained with propidium iodide. Measurement of fluorescence of 40 genotypes, whose published ploidy ranged from diploid to dodecaploid, indicated that fluorescence increased with an increase in chromosome number. Ploidy level accounted for 99% of the variation in fluorescence intensity (r 2 = 0.99) and variation among ploidy levels was much higher than within ploidy levels. This protocol was used successfully for genotypes representing eight different Rubus subgenera. Rubus ursinus Cham. and Schldl., a native blackberry species in the Pacific Northwest, which has been reported to have 6x, 8x, 9x, 10x, 11x, and 12x forms, was extensively tested. Genotypes of R. ursinus were predominantly 12x, but 6x, 7x, 8x, 9x, 11x, and 13x forms were found as well. Attempts to confirm the 13x estimates with manual counts were unsuccessful. Ploidy level of 103 genotypes in the USDA-ARS breeding program was determined by flow cytometry. Flow cytometry confirmed that genotypes from crosses among 7x and 4x parents had chromosome numbers that must be the result of nonreduced gametes. This technique was effective in differentiating chromosome numbers differing by 1x, but was not able to differentiate aneuploids. Nuclear DNA contents of 21 diploid Rubus species from five subgenera were determined by flow cytometry. Idaeobatus, Chamaebatus, and Anaplobatus were significantly lower in DNA content than those of Rubus and Cylactis. In the Rubus subgenus, R. hispidus and R. canadensis had the lowest DNA content and R. sanctus had the highest DNA content, 0.59 and 0.75 pg, respectively. Idaeobatus had greater variation in DNA content among diploid species than the Rubus subgenus, with the highest being from R. ellipticus (0.69 pg) and lowest from R. illecebrosus (0.47 pg).

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Eric Stafne*, John Clark, and Allen Szalanski

In this study, the nuclear ribosomal DNA internal transcribed spacer region (ITS) of six Rubus cultivars were sequenced, then compared with sequences of three Rubus species in Genbank. DNA sequencing revealed little genetic variation among blackberry cultivars, but ably revealed distinctions between blackberry and red raspberry genotypes. Analysis by maximum-parsimony and pairwise genetic distances confirmed the small variation among blackberry cultivars. The resulting sequences were analyzed for useful restriction sites and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis was conducted on a total of six cultivars to establish genetic variation. Digests were difficult to interpret due to heterogeneity at restriction sites.

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Fumiomi Takeda and John Phillips

15 Stiles, H.D. 1999 Limited arm-rotation shift-trellis (LARS) and primocane management apparatus (PMA) for raspberries and blackberries ( Rubus cvs. or crops) Virginia Agr. Expt. Sta. Bul. Ser. 99-1 Takeda, F. Peterson, D.L. 1999 Considerations for

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Christopher I. Vincent, M. Elena García, Donn T. Johnson, and Curt R. Rom

The broad mite (Polyphagotarsonemus latus) was found in association with leaf-curling symptoms on primocane-fruiting blackberry (Rubus rubus) in Arkansas in 2007–2009. Broad mite had not been previously reported on blackberry. The plots sampled in this study were part of a study comparing harvesting in the fall versus harvest in spring and fall, high tunnels versus ambient conditions, and three genotypes, all under organic production. Leaves were sampled, broad mites per leaf counted, and leaf area and trichome density measured. Results indicated that broad mite is capable of overwintering in a moderate temperate climate and that it reduces leaf area of primocane-fruiting blackberry. The fall-only harvest system had fewer broad mites than fall and spring harvest. There were a range of genotype effects on broad mite populations, including one genotype, ‘Prime-Jan®’, on which broad mite populations remained low, and one genotype, APF-46, on which mite populations grew significantly. Observations indicate that the broad mite may be a pest of ‘Prime-Ark® 45’, another primocane-fruiting cultivar.

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Rengong Meng, Chad E. Finn, and Robert P. Doss

Knowledge of the chromosome number in Rubus would be valuable when planning crosses and identifying plants, etc., however, preparation of tissue for microscopic evaluation and chromosome counting is difficult and time-consuming. Flow cytometry offers a more-efficient approach to this task. DNA flow cytometry was used to determine the nuclear DNA content in 22 Rubus genotypes. The genotypes represented a range of reported chromosome numbers from 2x to 12x. Six of the genotypes were representatives of Rubus ursinus, which is reported to have both 8x and 12x forms. Samples of nuclei were prepared from leaf discs of newly emerged and mature leaves following published protocols with some modifications. The DNA content was estimated by comparison of the fluorescence of Rubus nuclei with an internal DNA standard. There was an increase in nuclear DNA content concurrent with the increase in chromosome number. In these studies DNA flow cytometry could differentiate genotypes that differed by 2x, such as 6x and 8x, but could not reliably distinguish genotypes that differed by 1x, such as 7x vs. 8x or 6x. Aneuploids cannot be differentiated at this time.

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Renee T. Threlfall, Olivia S. Hines, John R. Clark, Luke R. Howard, Cindi R. Brownmiller, Daniela M. Segantini, and Lydia J.R. Lawless

Blackberries ( Rubus subgenus Rubus Watson) are a high-value specialty crop grown worldwide for fresh market and processing. Fresh blackberry fruit has potential for an increased role in commercial markets due to the increase of production and

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Javier Fernandez-Salvador, Bernadine C. Strik, and David R. Bryla

converted organic blackberry and red raspberry ( Rubus idaeus ) in 2007 ( Granatstein et al., 2010 ). Significant expansion in organic plantings is expected in the next 10 years as consumer demand for organic products increases and growers become more

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Javier Fernandez-Salvador, Bernadine C. Strik, and David R. Bryla

Fertilizer practices in blackberry ( Rubus L. subgenus Rubus Watson) are routinely adjusted based on leaf tissue analysis ( Hart et al., 2006 ). N is the predominant nutrient applied to trailing blackberry, and the best growth and yield are

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Johanne C. Cousineau and Danielle J. Donnelly

Isoenzyme staining was used to characterize 55 of 78 raspberry cultivars (Rubus idaeus L., R. × neglectus Peck, and R. occidentalis L.). Six enzymes were needed to achieve this characterization: isocitrate dehydrogenase, malate dehydrogenase, phosphoglucoisomerase, phosphoglucomutase, shikimic acid dehydrogenase, arid triose phosphate isomerase. The 23 cultivars that were not uniquely characterized were grouped into eight groups of two and two groups of three and four. Two of these groups comprised black raspberry cultivars, all of which were similar isozymically. Isoenzymes could not distinguish between the cultivar Willamette and a spine-free mutant of the cultivar. Analysis of cultivars obtained from several sources revealed that raspberry cultivar mislabeling exists but is not very prevalent. Regular isoenzyme analysis of raspberry cultivars held by germplasm repositories, certified and other propagators, and breeders is both feasible and advisable for early detection of cultivar mislabeling.