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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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Safi S. Korban

Abstract

Modem taxonomists classify the genus Malus into 25 to 30 species and several subspecies (9, 25). Most species of this genus intercross freely, since there are no evident physiological and genetic barriers. Moreover, collections of Malus found in arboreta are classified inadequately and usually are grown from seed which is generally a result of interspecific or intraspecific hybrids (9).

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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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Robert D. Marquard and Charlotte R. Chan

Forty-five crabapple (Malus spp.) cultivars were evaluated for 16 isozyme systems by starch gel electrophoresis. Of the 16 systems evaluated, 6 were useful in separating among cultivars. Enzyme systems used to distinguish among the cultivars included alcohol dehydrogenase, aspartate aminotransferase, malate dehydrogenase, 6-phosphogluconate dehydrogenase, phosphoglucoisomerase, and shikimate dehydrogenase. Each enzyme system produced one well-resolved polymorphic region except for 6-phosphogluconate dehydrogenase, which produced two. Most crabapple selections could be identified when all six enzymes were evaluated. Alcohol dehydrogenase had the most diagnostic banding patterns useful for cultivar identification.

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Hong Y. Yang, Schuyler S. Korban, Jutta Krüger, and Hanna Schmidt

Almost 200 random sequence decamer primers were used to screen a pair of bulked samples of apple (Malus ×domestica Borkh.) DNA and that of the donor parent Malus floribunda Sieb. clone 821 for molecular markers linked to the Vf gene conferring resistance to apple scab [Venturia inaequalis (Cke.) Wint.]. Identified was a single primer that generated a polymerase chain-reaction (PCR) fragment, OPAR4/1400, from the donor parent M. floribunda clone 821 and the scab-resistant selections/cultivars bulk, but not from the scab-susceptible recurrent-parent bulk. Cosegregation analysis using a segregating apple progeny and polymorphism analysis of individual scab-resistant selections/cultivars confirmed that this marker was linked to the scab-resistance gene Vf OPAR4/1400 was then cloned and sequenced. Sequence-specific primers of 25 oligonucleotides based on the marker were developed and used to screen further M. floribunda clone 821, scab-susceptible apple cultivars, scab-resistant apple cultivars, and scab-resistant Purdue, Rutgers, and Univ. of Illinois apple breeding program selections. The sequence-specific primers identified polymorphisms of OPAR4/1400 based on the presence or absence of a single band. This molecular marker is at a distance of about 3.6 cM from the Vf gene.

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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