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Paul M. Lyrene

averaged 7.8. This compares with an average of more than 26 large seeds per berry obtained in 74 highbush cultivar × highbush cultivar crosses made in the Florida blueberry breeding program ( Chavez and Lyrene, 2009 ). Some fertility reduction in the F 1

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Paul M. Lyrene

03n02 03 Ballington, J.R. Rooks, S.D. Cline, W.O. Meyer, J.R. Milholland, R.D. 1997 The North Carolina State University blueberry breeding program: Toward V. × covilleanum ? Acta Hort. 446 243 250 doi: 10.17660/ActaHortic.1997.446.36 Cane, J

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Ann Marie Connor, James J. Luby, and Cindy B.S. Tong

Narrow-sense heritability and among-family and within-family variance components were estimated for antioxidant activity (AA), total phenolic content (TPH), and anthocyanin content (ACY) in blueberry (Vaccinium L. sp.) fruit. AA, TPH, and ACY were determined in the parents and in 10 offspring from each of 20 random crosses for each of 2 years at Becker, Minn. Offspring-midparent regression analysis provided combined-year heritability estimates of 0.43 ± 0.09 (P ≤ 0.0001) for AA, 0.46 ± 0.11 (P ≤ 0.0001) for TPH, and 0.56 ± 0.10 (P ≤ 0.0001) for ACY. Analyses of variance delineated variation among and within families for AA, TPH, and ACY (P ≤ 0.001). Year-to-year variation in the means for all offspring genotypes was not significant for AA or TPH, but there were changes in rank between years for families and for offspring within families for these traits. Year-to-year variation in the mean for all offspring genotypes was significant for ACY, but rank changes were observed only among offspring within families, not among families. In total, 18 of 200 offspring from 7 of the 20 crosses were transgressive segregants for AA, exceeding the higher parent of the cross by at least two sds. Estimates of variance components showed that variation among families accounted for 24% to 27% of total variance for the three traits. However, variation within families was greater than that among families, accounting for 38% to 56% of total variance for the three traits. These results suggest that increasing antioxidant activity in blueberry through breeding is feasible, and that the breeding strategies utilized should exploit the large within-family variation that exists.

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Luping Qu and James F. Hancock

A tetraploid blueberry population resulting from a cross of US 75 {a tetraploid hybrid of Fla 4B [a selection of Vaccinium darrowi Camp (2n = 2x = 24) × `Bluecrop' [(V. corymbosum L. (2n = 4x = 48)]} × `Bluetta' (4x) was used to generate a genetic linkage map of US 75 by randomly amplified polymorphic DNA (RAPD) analysis. One hundred and forty markers unique for Fla 4B that segregated 1:1 in the population were mapped into 29 linkage groups that cover a total genetic distance of 1288.2 cM, with a range of 1.6 to 33.9 cM between adjacent markers. The map is essentially of V. darrowi because US 75 was produced via a 2n gamete from Fla 4B and only unique markers for Fla 4B were used. Therefore, all the chromosomes of V. darrowi could be represented in the map.

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J.F. Hancock, P.W. Callow, S.L. Krebs, D.C. Ramsdell, J.R. Ballington, M.J. Lareau, J.J. Luby, G.P. Pavlis, M.P. Pritts, J.M. Smagula, and N. Vorsa

Flower bud and leaf samples collected from a wide range of native North American Vaccinium populations were tested for the presence of blueberry shoestring virus (BBSSV) using the enzyme-linked immunosorbant assay. The highest disease incidence was found in Michigan (14%), although a few positive samples also were found in Virginia, New Jersey, Maine, Ontario, and Quebec. Of seven species tested, only V. corymbosum L. and V. angustifolium Ait. were infected with BBSSV.

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Paul M. Lyrene

Several hundred hybrid seedlings were produced by pollinating flowers of tetraploid highbush blueberry cultivars with pollen from 13 plants of Vaccinium stamineum that were selected as tetraploids following colchicine treatment. The hybrids were intermediate between the parents in many characteristics. They were less vigorous than the parents, but 46 plants flowered when 1.3 years old from seed. The F1 hybrids produced pollen abundantly, but only 30% of the microspores appeared potentially viable when viewed at 250X. F1 flowers that were pollinated with pollen from either parent taxon or with pollen from a different F1 hybrid produced thousands of well-developed seeds. The F1 hybrids were less successful when used as male parents in backcrosses to highbush, but 4790 well-developed seeds were obtained by pollinating 3250 highbush flowers. Flowers on F1 plants had long peduncles and pedicels, giving an open raceme. The flowers were open in the bud and had anther awns, two characteristics from V. stamineum. Berries on the F1 plants had black skins, and the ripe berries of 11 F1 plants had red to purple pulp like their V. stamineum parent. Berries on the hybrids were juicy. They had little or no bitterness typical of V. stamineum, and most had a pleasing balance of sugar and acid.

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T.F. Wenslaff and P.M. Lyrene

A yellow-leaf seedling marker, r, was used to determine if there was preferential chromosome pairing in a group of tetraploid southern highbush blueberry hybrids. Plants with four copies of r (no copies of R) fail to develop anthocyanins, and cotyledons, hypocotyls, leaves, stems, and other vegetative tissues have a bright yellow-green color. In the hybrids that were studied, two genomes were from the diploid wild species, V. elliottii Chapman, and both carried the recessive marker r. The other two genomes were from southern highbush cultivars and both carried the dominant wildtype allele, R. When RRrr hybrids were intercrossed or crossed to rrrr yellow-leaf plants, the number of yellowleaf rrrr seedlings obtained usually equalled or exceeded the number predicted from nonpreferential chromosome pairing. Since rr gametes can only be produced by RRrr plants when R and r chromosomes pair at Meiosis I, there was no evidence that the chromosomes derived from V. elliottii were pairing at a higher-than-random rate.

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Rogério Ritzinger and Paul M. Lyrene

Open-pollinated southern highbush (V. corymbosum L. hybrids) and F1 (southern highbush × V. simulatum Small) hybrid blueberry seedlings were compared for fertility in a high-density nursery in Gainesville, Fla. Most of the pollen sources in the field were tetraploid southern highbush seedlings. Berries were collected from 100 southern highbush seedlings and from 100 seedlings from southern highbush × V. simulatum crosses. The seeds were extracted and dried on a laboratory bench for several days before weighing. No significant differences were found in seed mass/berry between the two types of seedlings. Although the F1 interspecific hybrids averaged slightly lower in seed mass per berry, this was due to the smaller size of their well-developed seeds, not to poor seed development. The estimated number of well-developed seeds per berry was 35.4 and 39.1 for southern highbush blueberries and their F1 hybrids with V. simulatum, respectively. These results indicate that reduced fertility should not be a problem in using V. simulatum to breed southern highbush blueberries.