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Shujun Zhou, Guixue Zhou, and Kehu Li

number and discussed why the aneuploid embryos from the 3 x × 2 x /4 x crosses were able to survive and the potential significance of triploid for lily breeding. Materials and Methods Plant materials. Eight Asiatic lily cultivars were used ( Table 1

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Jiangbo Dang, Tingrong Wu, Guolu Liang, Di Wu, Qiao He, and Qigao Guo

Aneuploid is defined as individuals with one or multiple incomplete chromosome sets in the cells. Aneuploid occurs naturally in some plants such as Phalaenopsis ( Zhuang et al., 2007 ), and is frequently found in interploid hybridization

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Timothy Laverty and N. Vorsa

Vaccinium ashei (6x) /V. corymbosum (4x) pentaploid hybrids backcrossed to V. ashei yield aneuploid progeny ranging in chromosome number from 5x to 6x levels. Six backcross aneuploids having chromosome numbers of 2n = 61, 62, 64, 66, 68, and 70 were selected from this backcross and crossed in a complete diallel mating design and backcrossed (as female parents) to two V. ashei cultivars and an interspecific hexaploid hybrid. Fertility variables measured were percent fruit set, total seed per berry, developed seed per berry, percent developed seed per berry, percent seed germination, developed seed per pollination, and seedlings per pollination. A significant linear and positive relationship was found between chromosome number and all seven fertility variables. However, regression accounted for 30% or less of the variation among crosses. Diallel analysis revealed that general combining ability was the major contributing effect for all seven variables, followed by reciprocal effects. Specific combining ability was not significant. The second backcross to the hexaploid level suggested significant effects due to both the BC1 aneuploid and hexaploid genotypes and to a significant genotype × genotype interaction for three of the variables. All six aneuploids were either fully or partially self-sterile. The findings of this study substantiate earlier suggestions that pentaploids in blueberry can be used to facilitate bilateral transfer of characteristics between the tetraploid and hexaploid levels in blueberry.

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N. Vorsa and James R. Ballington

Eight highbush blueberry (V. corymbosum L.) triploids (2n = 3x = 36) were crossed with diploids (2n = 2x = 24), tetraploids (2n = 4x = 48), and hexaploids (2n = 6x = 72). No plants were recovered from 4021 3x × 2x crosses. One triploid was relatively fertile in 3x × 4x and 3x × 6x crosses, which is most likely attributable to 2n gamete production in the triploid. The lack of fertility of triploids, which do not produce 2n gametes, in crosses with diploids and tetraploids suggests that the production of gametes with numerically balanced (n = 12 or 24) chromosome numbers is extremely low. In addition, the inability to recover progeny from 3x × 2x crosses also suggests that aneuploid gametophytes and/or zygotes, including trisomics, are inviable in blueberry. Pollen stainability was also highly reduced in triploids. Frequency distributions of anaphase I pole chromosomal constitutions of three triploids were significantly different from one another. Two of the three distributions were shifted toward the basic chromosome number of 12, with one triploid having 25% poles with 12 chromosomes. However, the sterility of 3x × 2x and 2x × 3x crosses indicates that lagging chromosomes during meiotic anaphases are probably not excluded from gametes, resulting in unbalanced gametes in blueberry. Triploids can be used as a bridge to facilitate gene transfer from the diploid and tetraploid levels to the hexaploid level in blueberry.

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Alan T. Whittemore and Zheng-Lian Xia

reviewed by Ramsey and Schemske (1998) . Although meiosis in triploids produces a preponderance of aneuploid pollen with ≈1.5 sets of chromosomes, many triploids produce progeny that are euploid or close to euploid. The progeny of triploids fertilized with

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Shujun Zhou, Xin Tan, Liqin Fang, Jia Jian, Ping Xu, and Guoliang Yuan

= ‘Honesty’ × ‘Sarina’, 11418 = ‘Honesty’ × ‘Tresor’, 11431 = ‘Honesty’ × ‘Brunello’; bar = 1 cm. Based on GISH analyses, all progenies derived from hybridizations of ‘Honesty’ with the four autotetraploid paternal parents were aneuploid ( Fig. 3 ; Table 3

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Whitney D. Phillips, Thomas G. Ranney, Darren H. Touchell, and Thomas A. Eaker

., 2011 ), and ruellia ( Ruellia simplex ) ( Freyre and Moseley, 2012 ). Triploids are typically highly infertile; however, limited fertility and seed production can result from the formation of apomictic embryos or through the union of aneuploid or

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Todd J. Rounsaville, Darren H. Touchell, and Thomas G. Ranney

reported to be highly infertile ( Rayburn et al., 2009 ). However, in some cases, triploids can have limited fertility resulting from formation of apomictic embryos, unreduced gametes, and the union of aneuploid gametes ( Lim et al., 2003 ; Lo et al., 2009

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Jason D. Lattier and Ryan N. Contreras

, they can provide an important bridge in wide crosses and their range of gametes can be used in the production of high copy number polyploids such as tetraploids, pentaploids, and hexaploids ( Wang et al., 2010 ). Aneuploid progeny have been produced in

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Min Deng, Jianjun Chen, Richard J. Henny, and Qiansheng Li

( Table 1 ). Thus, the results from this study provide little further insight into the basic chromosome number question but suggest that some cultivars could be aneuploid. If 2 n chromosome numbers were 16 as proposed by Sharma and Bal (1958) , the