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Lisa Alexander

; however, may lead to some pollen or egg cells that contain no chromosomes and some that contain two sets of chromosomes ( Bretangolle and Thompson, 1995 ). Pollen or egg cells that contain a double set of chromosomes are termed “unreduced gametes.” The

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Ryan C. Graebner, Hsuan Chen, Ryan N. Contreras, Kathleen G. Haynes and Vidyasagar Sathuvalli

frequency of unreduced gametes. Van Suchtelen (1976) produced a low frequency of triploids and concluded that triploid clones generally resembled their tetraploid siblings in terms of morphology and yield. Finally, De Maine (1994) found that tetraploid

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Jason D. Lattier and Ryan N. Contreras

., 2013 ; Lattier, 2016 ; Parris et al., 2010 ; Shearer and Ranney, 2013 ). Polyploidy, or whole genome duplication, is a driving force in evolution and occurs naturally through somatic mutations in meristematic cells and through unreduced gametes

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Keri D. Jones, Sandra M. Reed and Timothy A. Rinehart

produced experimentally from hybridization of tetraploid and diploid individuals, but in nature, they usually arise from the union of unreduced (2n) and haploid (n) gametes. Unreduced gametes have been documented in many plant species ( Harlan and De Wet

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Hamid Ahmadi and Royce S. Bringhurst

Two groups of Fragaria decaploid (2n = 70, x = 7) breeding populations were studied. The first was derived from pentaploid (2n = 35) and hexaploid (2n = 42) natural or synethetic interspecific hybrids between octoploid (2n = 56) F. chiloensis (L.) Duch. or F. virginiana Duch. both from California, and various Fragaria diploids (2n = 14). Their chromosome number was doubled with colchicine or through the naturally generated unreduced gametes. They were selfed repetitively, intercrossed, and open pollinated. Gametic viability of the hermaphroditic and female decaploid hybrids exceeded 50%. The hybrids exhibited heterosis for runner production and vegetative vigor. Fragaria chiloensis bred for large fruit and desirable fruit qualities, and, in combination with diploids F. vesca L. and F. viridis Duch., resulted in hybrids that produced a single early spring crop and prolific runner production throughout the summer. Fragaria virginiana L. derivatives were characterized by high pollen fertility, and by day neutrality (photo-insensitivity). Together, they may contribute genes for adaptation to various regions and climates of the world and for pest and disease resistance. The second and most important group of decaploids involved here were those derived from hybrids between day-neutral octoploid cultivars (F. ×ananassa) crossed to F. vesca or F. viridis. This group of decaploids combined the genomes of the best octoploid cultivars with those of the above diploid species: facilitating the incorporation of genes responsible for high yield, day neutrality, and excellent fruit quality into the decaploid strawberries.

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Dario J. Chavez and Paul M. Lyrene

Various techniques have been used to overcome genetic crossing barriers between species in Vaccinium . Tetraploid blueberry plants have been produced by crossing diploid and tetraploid species. The production of unreduced gametes and the

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

unreduced gametes ( Ramsey and Schemske, 1998 ; Rounsaville et al., 2011 ). Flow cytometric screening of seeds and/or seedlings can often elucidate these reproductive pathways ( Eeckhaut et al., 2005 ; Matzk et al., 2000 ). Diploid plants, with standard

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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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David M. Czarnecki II and Zhanao Deng

formation of unreduced gametes (pollen and/or eggs). When an unreduced gamete unites with another unreduced gamete (bilateral) or with a normal haploid gamete (unilateral), the union leads to sexual polyploidization. To a certain extent, polyploidization via

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Kenji Sakurai, Susan K. Brown and Norman F. Weeden

The S alleles of 15 Japanese apple cultivars were determined by using the allele-specific polymerase chain reaction amplification and restriction enzyme digestion system developed by Janssens et al. (1995). Both S alleles were identified in eight diploid cultivars, two S alleles in three triploid cultivars, and one S allele in the remaining four diploid cultivars. Two cultivars had S alleles different than those predicted by their parentage, and in one comparison of a cultivar with its sport, an identity problem was discovered. The technique helped to indicate the parent contributing the unreduced gamete in triploids.