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Frederick J. Ryan and David W. Ramming

The development of grapevines with berries with small seed traces, so-called seedless grapes, is a costly process. Marker assisted selection would save time and money. Adam-Blondin et al. (Vitis 40:147. 2001) demonstrated that a sequence characterized amplified region, SCC8, could identify seedless grapevine cultivars in European accessions of Vitisvinifera L. We have applied this marker to two populations of grapevines in a breeding program in California. One population consisted of 100 individuals while the second had 109. The two crosses had a common female parent, derived from `Flame Seedless'. Fruit were evaluated over several seasons for parameters including total weight of seeds or traces. DNA was isolated from leaves during the spring. Amplification was carried out with SCC8 primers, followed by digestion with Bgl II, and agarose gel electrophoresis. Individuals were scored as homozygous SCC8+ (small seeded), heterozygous SCC8+/scc8-(intermediate sized seeds), or homozygous scc8-(large seeded) and mean total seed weight per berry was calculated for each genetic class. In the first population, the number of individuals in the inferred genotypes fit an expected 1:2:1 distribution (χ2 = 0.480, P> 0.787) and seed weights for each genetic class were reasonable. For the second population, it was necessary to postulate a null allele in one parent, with a 1:1:1:1 expected distribution for genotypes SCC8+/SCC8+, SCC8+/null, SCC8+/scc8-, and scc8-/null. The actual distribution was in agreement with this model (χ2 = 4.379, P> 0.223). The genotype SCC8+/null had the SCC8+ marker and total seed weight >10 mg per berry. Large seeded individuals and heterozygotes could be reliably identified with this marker.

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T. Casey Garvey and John D. Hewitt

An interspecific hybrid was made between an accession of Lycopersicon cheesmanii f. minor Riley (LA 1508) from the Galapagos Islands, Ecuador, and L. pennellii (Corr.) D'Arcy (LA 716). LA 1508 was used because of its high soluble solids content (SSC). It was crossed with LA 716 to test for linkage between isozymes and morphological markers and loci conditioning high SSC. For both accessions, chromosome numbers are equal and there are large differences between SSC and no barriers to crossing. Modified BC1 populations derived from the hybridization were assayed for isozyme markers using starch gel electrophoresis. Associations between marker loci and quantitative-trait loci (QTL) conditioning high SSC were determined using analysis of variance. Six isozymes located on five chromosomes and one morphological marker had significant associations with SSC, indicating linkage to QTL. Digenic epistatic interactions between pairs of independent markers did not appear to play an important role in the interactions between QTL that condition SSC.

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David M. Czarnecki II, Madhugiri Nageswara Rao, Jeffrey G. Norcini, Frederick G. Gmitter Jr, and Zhanao Deng

how results from molecular marker analyses would be related with phenotypic findings. Materials and Methods Plant materials. Seeds or plants were collected from three types of C. leavenworthii populations (natural or native, production

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Troy D. Carson, Donald B. White, and Alan G. Smith

( Law et al., 1977 ; Warwick and Briggs, 1978a , 1978b ). Others have examined the genetic relatedness of various populations in differing environments through the use of molecular markers. Darmency et al. (1992) and Darmency and Gasquez (1997

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Maria Jose Gonzalo, Marin Talbot Brewer, Claire Anderson, David Sullivan, Simon Gray, and Esther van der Knaap

analysis. The PCA was conducted by the command “proc princomp” using SAS. The results include the simple statistics (mean and standard deviation of each coordinate), correlation matrix, and the eigenvectors for each PC. The association of molecular

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Ambika B. Gaikwad, Tusar Kanti Behera, Anand K. Singh, Devanshi Chandel, Jawahir L. Karihaloo, and Jack E. Staub

.S. Wall, S.J. Senior, M.L. Mitchell, S.E. Kresovich, S. Ziegle, J. 1997 An evaluation of the utility of SSR loci as molecular markers in maize ( Zea mays L.): Comparisons with data from RFLPs and pedigree Theor

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Xiaoli Wang, Zhiyong Wang, Li Liao, Xinyi Zhang, and Changjun Bai

variation using molecular markers to advance the genetic breeding of carpetgrass. Most studies of carpetgrass have focused on its genetic characteristics and resistance ( Samarakoon et al., 1990 ; Smith and Whiteman, 1983 ; Uddin et al., 2009 ; Xi et al

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Yan Liu, Hailin Guo, Yi Wang, Jingang Shi, Dandan Li, Zhiyong Wang, and Jianxiu Liu

; Wang et al., 2011 ). Several molecular markers, such as restriction fragment length polymorphism markers, simple sequence repeat markers, amplified fragment length polymorphism markers, and RAPD markers have been used to research the genetic diversity

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M.A. Dalbó, G.N. Ye, N.F. Weeden, W.F. Wilcox, and B.I. Reisch

The efficiency of marker-assisted selection for powdery mildew (Uncinula necator (Schw.) Burr) resistance in grapes (Vitis L. sp.) was studied using molecular markers associated with a major QTL (quantitative trait loci) for this trait. Initially, genetic maps were constructed from a segregating population of the cross `Horizon' × Illinois 547-1 (a hybrid between V. rupestris Scheele and V. cinerea Engelm.). A major QTL from Ill. 547-1, the resistant parent, explained 41% of the variation. One RAPD (randomly amplified polymorphic DNA) marker and one AFLP (amplified fragment length polymorphism) marker, obtained by bulked segregant analysis, showed the highest association with powdery mildew resistance in the mapping population. Segregation of the QTL was followed in different crosses by CAPS (cleaved amplified polymorphic sequence) markers developed from these two markers. An allele-specific amplified polymorphism that segregates as present/absent was also developed from the CS25b locus. Powdery mildew resistance was evaluated visually on a 1 to 5 scale in four different seedling populations. Two populations originated from crosses using Ill. 547-1 as the resistant parent. Two other populations were from crosses with NY88.0514.03, a resistant seedling from the original `Horizon' × Ill. 547-1 mapping population. Segregation ratio distortions were observed in some crosses. In these cases, the allele associated with the QTL for powdery mildew resistance was less frequent than the alternate allele. In all crosses, the markers were closely associated with resistance. If selection were based on markers, the percentage of susceptible individuals (classes 4 and 5) would decrease from 24% to 52% to 2% to 18%. Selection efficiency was greatest in crosses where segregation distortion was most intense.

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Naomi R. Smith, Robert N. Trigiano, Mark T. Windham, Kurt H. Lamour, Ledare S. Finley, Xinwang Wang, and Timothy A. Rinehart

genotype rather than solely on phenotypic characteristics. Molecular markers can be very useful in cultivar identification or in determination of parentage of sexually propagated species. This is particularly important for proprietary plants, because