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Minou Hemmat, Norman F. Weeden, and Susan K. Brown

We mapped DNA polymorphisms generated by 41 sets of Simple Sequence Repeat (SSR) primers, developed independently in four laboratories. All primer sets gave polymorphisms that could be located on our `White Angel' x `Rome Beauty' map for apple [Malus sylvestris (L.) Mill. Var. domestica (Borkh.) Mansf.]. The SSR primers were used to identify homologous linkage groups in `Wijcik McIntosh', NY 75441-58, `Golden Delicious', and `Liberty' cultivars for which relatively complete linkage maps have been constructed from isozyme and Random Amplified Polymorphic DNA (RAPD) markers. In several instances, two or more SSRs were syntenic, and except for an apparent translocation involving linkage group (LG) 6, these linkages were conserved throughout the six maps. Twenty-four SSR primers were consistently polymorphic, and these are recommended as standard anchor markers for apple maps. Experiments on a pear (Pyrus communis L.) population indicated that many of the apple SSRs would be useful for mapping in pear. However some of the primers produced fragments in pear significantly different in size than those in apple.

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Gayle M. Volk, Christopher M. Richards, Ann A. Reilley, Adam D. Henk, Philip L. Forsline, and Herb S. Aldwinckle

Seeds and scionwood of Malus sieversii Lebed. have been collected from wild populations of apple trees in Kazakhstan. Seedlings and grafted trees were planted in the orchards at the U.S. Dept. of Agriculture Plant Genetic Resources Unit in Geneva, N.Y. We developed core collections to capture the genetic and phenotypic diversity represented in the trees from each of two of the Kazakhstan collection sites. These core collections capture more than 90% of the genetic diversity of the original populations, as determined using seven unlinked simple sequence repeat markers and 19 quantitative traits. Since phenotypic evaluations of these materials have been completed, the 35 trees within each population will be used as parents in crosses so that the genetic diversity in the orchard populations can be captured as seed for long-term ex situ conservation. This strategy of storing seeds, rather than maintaining costly field collections, could be applied to other collections of wild plant materials in the National Plant Germplasm System.

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Chunyu Zhang, Xuesen Chen, Hongwei Song, Yinghai Liang, Chenhui Zhao, and Honglian Li

Apple ( Malus pumila ) is a fruit crop of major economic importance. In worldwide apple breeding efforts, apple breeders typically intercross elite or commercial cultivars, such as Red Delicious, Golden Delicious, and Jonathan, which results in

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Christopher M. Richards, Gayle M. Volk, Patrick A. Reeves, Ann A. Reilley, Adam D. Henk, Philip L. Forsline, and Herb S. Aldwinckle

exploration teams collected Malus sieversii seeds and clones from Kazakhstan between 1989 and 1996 ( Dzhangaliev, 2003 ; Forsline et al., 2003 ; Hokanson et al., 1997 ; Luby et al., 2001 ). Over one thousand trees derived from seeds collected during these

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Carole L. Bassett, D. Michael Glenn, Philip L. Forsline, Michael E. Wisniewski, and Robert E. Farrell Jr

then by humans over the silk road trade routes into Europe. The modern cultivated apple ( Malus × domestica Borkh.) is believed to have been domesticated in Turkestan, now Kazakhstan, Kyrgyzstan, Uzbekistan, Turkmenistan, and Tajikistan ( Harris et al

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Yi Tan, Baisha Li, Yi Wang, Ting Wu, Zhenhai Han, and Xinzhong Zhang

; Requesens et al., 2014 ; Zhang et al., 2014 ). A high rate of in vitro regeneration is the first prerequisite for successful transformation, but many woody perennials such as Malus species are rather recalcitrant to regeneration. The regeneration ability

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Gayle M. Volk, Adam D. Henk, Christopher M. Richards, Philip L. Forsline, and C. Thomas Chao

The mountains of Central Asia have forest species that include Malus sieversii (Ledeb.) M. Roem., a highly diverse apple crop wild relative. The Russian scientist Vavilov explored the forests of Central Asia in the 1920s and made note of the wide

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Meiling Yang, Fang Li, Hong Long, Weiwei Yu, Xiuna Yan, Bin Liu, Yunxiu Zhang, Guorong Yan, and Wenqin Song

Malus sieversii (Ledeb.) Roem. is a wild apple species native to Central Asia. Its provenance includes the region of the Tienshan Mountains, extending from China to Kyrgyzstan and Kazakhstan. It has been recognized as one of the major progenitors

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Tingting Sun, Tingting Pei, Zhijun Zhang, Mingjun Li, Linlin Huang, Cuiying Li, Xueyan Shi, Minghui Zhan, Xiaoyu Cao, Fengwang Ma, and Changhai Liu

-PCR System machine (Bio-Rad iQ 5; Bio-Rad, Hercules, CA). The following gene-specific primers for qRT-PCR were designed with Primer Premier 6 software (Biosoft International, Palo Alto, CA). Transcripts of the Malus elongation factor 1 alpha gene were used

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Briana L. Gross, Gayle M. Volk, Christopher M. Richards, Philip L. Forsline, Gennaro Fazio, and C. Thomas Chao

programs that address threats to apple crop production. The Malus collection is maintained as grafted, clonally propagated trees and own-rooted seedling trees. The grafted orchards include 33 species of Malus , of which only one species, Malus