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Quantitative trait loci (QTL) analysis was carried out with a set of 114 recombinant inbred lines (RILs) from the International Triticeae Mapping Initiative (ITMI) population of ‘W7984’ × ‘Opata 85’ to identify genomic regions controlling traits related to post-anthesis drought tolerance of wheat ( Triticum aestivum L.). In two experiments performed in Gatersleben in 2001 and 2003, the amount stem reserves mobilisation was estimated by measuring of changes in 1000-grain weight after chemical desiccation treatment. QTLs for stem reserves mobilisation (Srm) were mapped on chromosomes 2D, 5D and 7D. The mapping positions obtained in the present investigation are discussed with respect to studies on drought tolerance performed in wheat previously. QTLs for drought tolerance preferentially appeared in homoeologous regions at distal parts of the group 7 chromosomes.

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Pshenichnikova, T.A., Ermakova, M.F., Chistyakova, A.K., Shchukina, L.V., Berezovskaya, E.V., Lohwasser, U., Röder, M., Börner, A. 2008a. Mapping of the quantitative trait loci (QTL) associated with grain quality characteristics of the bread wheat grown under

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The aim of the project is the detection, genetic mapping and characterization of quantitative trait loci (QTL) that confer resistance against Fusarium head blight in a resistant line of Triticum dicoccum .

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Freezing tolerance is a quantitative trait, determined by many genes and also influenced by environmental factors. Thus, the development of reliable testing methods is a prerequisite both for the identification of quantitative trait loci (QTLs) and for the identification of the genes behind the QTLs. Transformation methods proved to be effective in the direct verification of isolated genes involved in low temperature stress responses. In order to develop freezing tolerance, winter cereals must be adapted through a cold hardening period, which not only influences cold adaptation but also initiates the vernalization process necessary for flowering. Recent and ongoing studies are endeavouring to uncover the relationship between freezing tolerance and vernalization response at the genetic and molecular levels. This review aims to explain cereal freezing tolerance on the basis of recent discoveries in the areas outlined above.

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Rice ( Oryza sativa L.) is one of the most important crops in the world, especially Asian countries. Genetics of important traits in rice for yield improvement have always been a major breeding objective. Agronomic traits are inherited quantitatively, so quantitative trait loci (QTL) mapping for the potential use of molecular markers would be very helpful to plant breeders in developing improved rice varieties. In this investigation, a SSR linkage map of 1440.7cM of rice was constructed using 105 polymorphic simple sequence repeat (SSR) markers. The mapping population of 236 F 2:3 families derived from the cross of two rice varieties (Gharib × Sepidroud) was used for QTL mapping of agronomic traits. As many as 38 QTLs were detected to be associated with agronomic characteristics; some of them are being reported for the first time. The identified QTLs on specific chromosome regions explaining high phenotypic variance could be considered to use in marker-assisted selection (MAS) programs.

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Quantitative Trait Loci (QTL) mapping was carried out in a set of 114 lines of the International Triticeae Mapping Initiative (ITMI) mapping population for null nitrogen fertilization during two agricultural cycles. We quantified phenologic parameters (days to: ear emergency time, flowering time) and components of yield (number of plants and ears, plant height, leaf area, length and weight of ear, spikelet number, number and total weight of grains and by third in the ear, weight of thousand grains and total yield). Interval mapping resulted of 138 QTLs, of which 47 were catalogued as major QTLs (LOD ≥ 3.0) and 91 as minor QTLs (LOD 2.0 >0 2.9). The QTLs were distributed in 14 of the 21 chromosomes of wheat. The data showed that a high percentage of QTLs were in chromosomes 2D (49 or 35.5%), followed by 5A (22 or 15.9%), 1B (10 or 7.2%).

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Quantitative Trait Loci (QTL) analyses were conducted in a mapping population of 91 F2 plants derived from a cross between two ahu rice cultivars of Assam, Cheni ahu (dormant, Oryza sativa ssp. indica) and Kolong (non-dormant, Oryza sativa ssp. indica) in order to identify genomic regions affecting seed dormancy and the duration of dormancy. The linkage map based on 70 simple sequence repeat (SSR) markers detected two QTLs for seed dormancy (qSD5, qSD11) and one QTL for duration of dormancy (qSDD5), and came from the dormant parent. The levels of dormancy increased with the presence of any one of the QTLs but qSD5 had larger effect on increasing dormancy, indicating that dormancy could be effectively enhanced by more than one QTL. The QTLs detected could be used to develop near-isogenic lines (NILs) for map-based cloning of seed dormancy in rice, thus to improve the understanding of dormancy of indica rice.

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A panel of 94 diverse hexaploid wheat accessions was used to map quantitative trait loci (QTL) underlying the yield related traits on chromosome 3A. Population structure and kinships were estimated using unlinked SSR markers from all 21 chromosomes. Analysis of variance revealed significant difference among accessions; however, genotype × year interaction was non-significant for majority of yield related traits. A mixed linear model (MLM) approach identified six QTLs for four traits that individually accounted for 10.7 to 17.3% phenotypic variability. All QTLs were consistently observed for both study years. New putative QTLs for the maximum fertile florets per spike and spike length were identified. This report on QTLs for yield related traits on chromosome 3A will extend the existing knowledge and may prove useful in marker-assisted selection (MAS) for development of high yielding cultivars.

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Quantitative trait loci (QTL) for 11 morphometric body measurements of the hybrids of silver (Hypophthalmichthys molitrix) and bighead carp (H. nobilis) including body weight (BW), standard length (SL), body depth (BD), body thickness (BT), head length (HL), head depth (HD), length of ventral keel (LVK), length of pectoral fin (Lpec), length of pelvic fin (Lpel), length of caudal fin (Lcau) and space between pectoral and pelvic fins (SPP) were located on the sex average microsatellite linkage map constructed using the hybrids of a female bighead and a male silver carp, on which 15 microsatellites were newly mapped. One locus was found to be responsible for BW, LV K and SPP, respectively. As many as 6 loci were found to be responsible for HD. The variances of remaining traits were partitioned by different numbers of loci varying between 2 and 5. The variance explained each locus ranged from 9.1% to 23.8% of the total. The variance explained by all loci responsible for each measurement ranged from 17.7% to 75.1%. It was noted that multiple measurements were mapped on the same locus. For example, a region bounded by Hym435 and Hym145 was found to be responsible for all the measurements analyzed.

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Mapping of quantitative trait loci (QTL) was carried out in a set of 114 RILs of the International Triticeae Mapping Initiative (ITMI) mapping population under salt stress. Seedling population was grown during 8 days, under salt treatment (Hoagland’s ½ strength + 110 mM NaCl, EC 12.4 mS/cm) and normal treatment (Hoagland’s ½ strength, EC 0.9 mS/cm). We calculated starch degradation, measuring the dry weight of the grains on the 4th, 6th and 8th days of culturing. Formation of biomass was calculated measuring leaf and root length on the 4th, 6th and 8th days of culture. Interval mapping resulted in 13 QTLs, 2 major QTLs (LOD> 3) and 11 minors QTLs (LOD> 2). A total of 10 QTLs were associated with saline treatment and 3 QTLs at normal treatment. The data show that a high percentage of QTLs were in chromosomes 2B (3, 23.0%), and 1A (3, 23.0%), followed by 4D (2, 13.6%).

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