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Ana B. Monteagudo, A. Paula Rodiño, Margarita Lema, María De la Fuente, Marta Santalla, Antonio M. De Ron, and Shree P. Singh

Availability of germplasm with high level of resistance is essential for broadening the genetic base and breeding crop cultivars resistant to abiotic and biotic stresses. The objective of this study was to determine reaction of a common bean core collection from the Iberian Peninsula to anthracnose, rust, common and halo blights, bean common mosaic virus (BCMV, a potyvirus) and bean common mosaic necrosis virus (BCMNV, a potyvirus) pathogens. Of 43 accessions evaluated, 14 large-seeded Andean type, seven small-seeded Middle American type and seven with intermediate characteristics or recombinant type between the two gene pools had resistant reaction to one or more diseases. Resistance to race 17 or 23 of anthracnose pathogen was present in 17 accessions and four accessions were resistant to both races. Resistance to race 38 or 53 of rust pathogen was shown by 22 accessions and five accessions were resistant to both races. All accessions were susceptible to common bacterial blight and 12 accessions had resistance to halo blight. Ten accessions showed resistance to BCMV, none to BCMNV, and two were variable to both viruses. Accessions such as PHA-0573 (pinto), PHA-0589 (marrow), PHA-0654 (favada pinto), and PHA-0706 (favada) showed resistance to two or more diseases. These accessions may be valuable in breeding Andean bean for enhancing simultaneous utilization of both large seed size and disease resistance.

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Zhengwang Jiang, Feiyan Tang, Hongwen Huang, Hongju Hu, and Qiliang Chen

The sand pear (Pyrus pyrifolia Nakai) is an important fruit crop in China. In this study, simple sequence repeats (SSRs) were used to estimate the level and pattern of genetic diversity among 233 sand pear landraces collected from 10 different geographic regions in China. The results demonstrated that the SSR technique is an effective tool for assessing genetic diversity and the geographic pattern of genetic variation among sand pear landraces of different origins. A total of 184 putative alleles was detected using 14 primer pairs with an average of 13.1 alleles per locus. The mean expected heterozygosity and observed heterozygosity across all loci were 0.705 and 0.671, respectively. High genetic diversity was found in all populations except for that originated from Jiangxi (A e = 3.149; H e = 0.655), whereas at the regional level, those from central China were less diverse than those from other regions. Analysis of molecular variance showed that most genetic differences resided among landraces within populations. Additionally, unweighted pair group with arithmetic average clustering and principal component analysis plotting based on Nei's genetic distance revealed distinct gene pools in agreement with geographic distribution.

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Dongyan Hu, Zuoshuang Zhang, Donglin Zhang, Qixiang Zhang, and Jianhua Li

Ornamental peach (Prunus persica (L.) Batsch) is a popular plant for urban landscapes and gardens. However, the genetic relationship among ornamental peach cultivars is unclear. In this report, a group of 51 ornamental peach taxa, originated from P. persica and P. davidiana (Carr.) Franch., has been studied using AFLPs. The samples were collected from China, Japan, and US. A total of 275 useful markers ranging in size from 75 to 500 base pairs were generated using six EcoRI/MseI AFLP primer pairs. Among them, 265 bands were polymorphic. Total markers for each taxon ranged from 90 to 140 with an average of 120. Two clades were apparent on the PAUP–UPGMA tree with P. davidiana forming an outgroup to P. persica, indicates that P. davidiana contributed less to the ornamental peach gene pools. Within P. persica clade, 18 out of 20 upright ornamental peach cultivars formed a clade, which indicated that cultivars with upright growth habit had close genetic relationship. Five dwarf cultivars were grouped to one clade, supported by 81% bootstrap value, indicating that they probably derived from a common gene pool. These results demonstrated that AFLP markers are powerful for determining genetic relationships in ornamental peach. The genetic relationships among ornamental cultivars established in this study could be useful in ornamental peach identification, conservation, and breeding.

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Júlia Halász, Andrzej Pedryc, Sezai Ercisli, Kadir Ugurtan Yilmaz, and Attila Hegedűs

The S-genotypes of a set of Turkish and Hungarian apricot (Prunus armeniaca L.) cultivars were determined by polymerase chain reaction (PCR) amplification of their S-RNase intron regions. In addition, the S-genotyping method was extended to the SFB gene to detect the non-functional S C-haplotype and hence reliably identify self-compatible apricot cultivars. We determined the complete S-genotype of 51 cultivars and the partial S-genotype of four cultivars. A total of 32 different S-genotypes were assigned to the 51 cultivars, and many of them (28) were classified into newly established cross-incompatibility groups III through XIV. Another 12 cultivars demonstrated unique incompatible genotypes and seven self-compatible cultivars were identified in the examined accessions. The fact that Turkish and Hungarian apricot cultivars carry 12 and five S-alleles, respectively, and all five alleles detected in Hungarian cultivars were also present in Turkish apricots furnished molecular evidence supporting the long-suspected historical connection between Hungarian and Turkish apricots. The connection between these two gene pools appeared to be relatively recent and associated with historical events dating back 300 years. Our results confirm that Turkish germplasm contributed considerably to the development of several desirable Hungarian apricot cultivars. Results suggest that the mutation rendering the S C-haplotype non-functional might have occurred somewhere east of central Turkey.

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Yan Chen and Jayesh B. Samtani

, the contribution of Asian germplasm to U.S. horticulture will increase as researchers continue to use its rich gene pools to develop cultivars with superior qualities. Literature Cited Hummer, K. 2007 Introduction (for workshop “Plant Exploration for

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Shuang Jiang, Haishan An, Xiaoqing Wang, Chunhui Shi, Jun Luo, and Yuanwen Teng

STRUCTURE [version 2.3.4 ( Evanno et al., 2005 ; Pritchard et al., 2000 )]. This revealed the genetic structure by assigning individuals or predefined groups to clusters. Six runs of STRUCTURE were performed with the number of homogeneous gene pools ( K

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Benard Yada, Gina Brown-Guedira, Agnes Alajo, Gorrettie N. Ssemakula, Robert O.M. Mwanga, and G. Craig Yencho

-term geographic adaptations of breeding lines such as the African, Asian, and South and North American heterotic groups ( Grüneberg et al., 2009 ). Molecular markers will enable identification of potential heterotic gene pools within populations of breeding

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Cunquan Yuan, Zhiyi Qu, Huitang Pan, Tangren Cheng, Jia Wang, and Qixiang Zhang

primers (C64326) showed stable polymorphism between parents (T2 and P2) and gene pools (B T and B P ) ( Fig. 2 ). The obtained marker c64326 was further validated in the F 1 population of T2 × P2 (115 offspring), and the genetic linkage distance between

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Ryan J. Hayes, Karunakaran Maruthachalam, Gary E. Vallad, Steven J. Klosterman, and Krishna V. Subbarao

gene pool of lettuce comprises germplasm that is fully interfertile with L. sativa , including the wild species L. serriola and several L. serriola -like species. Lactuca saligna and L. virosa represent the secondary and tertiary gene pools

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Amnon Levi, Alvin M. Simmons, Laura Massey, John Coffey, W. Patrick Wechter, Robert L. Jarret, Yaakov Tadmor, Padma Nimmakayala, and Umesh K. Reddy

(CLL) gene pools are shown in dark blue and mustard color, respectively. The ancestry from the inferred Citrullus colocynthis (CC) gene pools are shown in yellow (Group 1), red (Group 2), green (Group 3), light blue (Group 4), and purple (Group 5