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Cecilia E. McGregor, Vickie Waters, Tripti Vashisth and Hussein Abdel-Haleem

. Jouanne, S. Coubriche, D. Jamin, P. Moreau, L. Charcosset, A. 2009 Fine mapping and haplotype structure analysis of a major flowering time quantitative trait locus on maize chromosome 10 Genetics 183 1555 1563 Ducrocq, S. Madur, D. Veyrieras, J.-B. Camus

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Xiaohe Song and Zhanao Deng

1 are presented in Table 2 . Fig. 2. Quantitative trait locus (QTL) mapping for powdery mildew (PM) resistance in gerbera breeding line UFGE 4033. The x-axis shows the genetic linkage map of gerbera linkage group 1 (LG1) calculated by MAPMAKER

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Geoffrey Meru and Cecilia E. McGregor

the quantitative trait locus associated with resistance to Fusarium oxysporum f. sp. niveum race 2 and the corresponding 2-likelihood-odds (LOD) support interval for separate and joint data for disease severity observed at 26 d after inoculation

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Xuefei Ning, Xianlei Wang, Zhijie Yu, Simeng Lu and Guan Li

, shape, and weight detected on WinQTLCart 2.5. Mapping of quantitative trait locus (QTL) correlated with seed shape in LG I also identified significant QTL for SL in this region. Fine genetic and physical mapping of the wave seed and tight-placenta locus

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Patrick D. O'Boyle, James D. Kelly and William W. Kirk

, P.M. Mundt, C. Richardson, K. Sandoval-Islas, S. Vivar, H. 2003 Pyramiding and validation of quantitative trait locus (QTL) alleles determining resistance to barley stripe rust: effects on adult plant

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Jen Colcol Marzu, Elizabeth Straley and Michael J. Havey

Pink root [PR (caused by Phoma terrestris)] is a major soil-borne disease of onion (Allium cepa) and reduces both yield and quality of bulbs. PR-resistant cultivars offer the best control option for this disease. The objectives of this study were to complete genetic analyses and mapping of PR resistances from independent sources. Segregating families were developed from different sources of PR resistance and evaluated using a seedling screen. PR severity in two segregating families from the same source of resistance mapped to one position on chromosome 4 with logarithm of odds (LOD) scores of 8.0 and 10.3, and explained 28% and 35% of the phenotypic variation, respectively. Estimates of additive and dominance effects revealed this source of PR resistance is codominantly inherited. PR resistance from a second source was assessed by percent survival in the seedling evaluation, showed codominance, and mapped to the same region on chromosome 4 at LOD 12.5 and explained 54% of the phenotypic variation. This research demonstrates that PR resistance from different sources mapped to the same chromosome region and showed similar modes of inheritance.

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Aliya Momotaz, Jay W. Scott and David J. Schuster

linkage between a marker locus and a quantitative trait locus Theor. Appl. Genet. 85 353 359 Denholm, I. Cahill, M. Byrne, F.J. Devonshire, A.L. 1996 Progress with documenting and combating

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Christina H. Hagerty, Alfonso Cuesta-Marcos, Perry Cregan, Qijian Song, Phil McClean and James R. Myers

Snap bean (Phaseolus vulgaris L.) breeding programs are tasked with developing cultivars that meet the standards of the vegetable processing industry and ultimately that of the consumer, all the while matching or exceeding the field performance of existing cultivars. While traditional breeding methods have had a long history of meeting these requirements, genetic marker technology, combined with the knowledge of important quantitative trait loci (QTL), can accelerate breeding efforts. In contrast to dry bean, snap bean immature pods and seeds are consumed as a vegetable. Several pod traits are important in snap bean including: reduced pod wall fiber, absence of pod suture strings, and thickened, succulent pod walls. In addition, snap bean pods are selected for round pod cross section, and pods tend to be longer with cylindrical seed shape. Seed color is an important trait in snap bean, especially those used for processing, as processors prefer white-seeded cultivars. The objective of this study was to investigate the genetic control of traits important to snap bean producers and processors. RR6950, a small seeded brown indeterminate type IIIA dry bean accession, was crossed to the Oregon State University (OSU) breeding line OSU5446, a type I Blue Lake four-sieve breeding line to produce the RR138 F4:6 recombinant inbred (RI) mapping population. We evaluated the RR138 RI population for processing and morphological traits, especially those affecting pods. The RR138 population was genotyped with the BARCBean6K_3 Beadchip, and single nucleotide polymorphisms (SNPs) were used to assemble a linkage map, and identify QTL for pod traits. The linkage map produced from this study contained 1689 SNPs across 1196cM. The map was populated with an average of one SNP per 1.4 cM, spanning 11 linkage groups. Seed and flower color genes B and P were located on Pv02 and Pv07, respectively. A QTL for string:pod length (PL) ratio was found on Pv02 controlling 32% of total genetic variation. QTL for a suite of important processing traits including pod wall fiber, pod height, pod width, and pod wall thickness were found clustering on Pv04 and controlled 21%, 26%, 18%, and 16% of genetic variation for each of these respective traits. A QTL for PL was found on Pv09 controlling 5% of genetic variation.

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I. Paran, I.L. Goldman and D. Zamir

Quantitative trait loci influencing morphological traits were identified by restriction fragment length polymorphism (RFLP) analysis in a population of recombinant inbred lines (RIL) derived from a cross of the cultivated tomato (Lycopersicon esculentum) with a related wild species (L. cheesmanii). One-hundred-thirty-two polymorphic RFLP loci spaced throughout the tomato genome were scored for 97 RIL families. Morphological traits, including plant height, fresh weight, node number, first flower-bearing node, leaf length at nodes three and four, and number of branches, were measured in replicated trials during 1991, 1992, and 1993. Significant (P ≤ 0.01 level) quantitative trait locus (QTL) associations of marker loci were identified for each trait. Lower plant height, more branches, and shorter internode length were generally associated with RFLP alleles from the L. cheesmanii parent. QTL with large effects on a majority of the morphological traits measured were detected at chromosomes 2, 3, and 4. Large additive effects were measured at significant marker loci for many of the traits measured. Several marker loci exhibited significant associations with numerous morphological traits, suggesting their possible linkage to genes controlling growth and development processes in Lycopersicon.

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Xiaoying Li, Hongxia Xu, Jianjun Feng and Junwei Chen

Deep transcriptome sequencing allows for the acquisition of large-scale microsatellite information, and it is especially useful for genetic diversity analysis and mapping in plants without reference genome sequences. In this study, a total of 14,004 simple sequence repeats (SSRs) were mined from 10,511 unigenes screening of 63,608 nonredundant transcriptome unigenes in loquat (Eriobotrya japonica) with a frequency of 22 SSR loci distributed over 100 unigenes. Dinucleotide and trinucleotide repeat SSRs were dominant, accounting for 20.62%, and 42.1% of the total, respectively. Seventy primer pairs were designed from partial SSRs and used for polymerase chain reaction (PCR) amplification. Of these primer pairs, 54 exhibited amplification and 33 were polymorphic. The number of alleles at these loci ranged from two to 17, and the polymorphism information content values ranged from 0.24 to 0.89. We tested the transferability of 33 SSR polymorphic primer pairs in apple and pear, and the transferability rates in these two species were 90.9% and 87.9%, respectively. A high level of marker polymorphism was observed in apple [Malus ×domestica (66.7%)], whereas a low level was observed in pear [Pyrus sp. (51.5%)]. In addition, the PCR products from seven SSR primer pairs were selected for sequence analysis, and 89.2% of the fragments were found to contain SSRs. SSR motifs were conserved among loquat, apple, and pear. According to our sequencing results for real SSR loci, ≈12,490 SSR loci were present in these loquat unigenes. The cluster dendrogram showed a distinct separation into different groups for these three species, indicating that these SSR markers were useful in the evaluation of genetic relationships and diversity between and within the species of Maloideae in the Rosaceae. The results of our identified SSRs should be useful for genetic linkage map construction, quantitative trait locus mapping, and molecular marker-assisted breeding of loquat and related species.