Showing 8 results for Qtl
, Reza Darvishzadeh, , , ,
Volume 7, Issue 3 (11-2016)
Abstract
One of the newest methods in plant breeding programs is mapping quantitative trait loci (QTL) with molecular markers. In order to identify QTL associated with some chemical traits such as chlorine, nicotine, sugar concentrations and ash in oriental tobacco, a population of 55 recombinant inbred lines coming from the cross Basma seres 31 × SPT406 were evaluated for above mentioned traits. QTL mapping was performed using linkage map developed on 103 recombinant inbred lines by 64 molecular markers including 14 SSR, 24 ISSR and 26 retrotransposone. The linkage map is composed of 7 linkage groups (LGs). Composite interval mapping revealed 5 QTLs associated with studied traits. Phenotypic variation explained by identified QTLs varied between 0.34 and 0.70. Any QTL was not detected for sugar concentration in tobacco leaves. Common markers between some of studied traits can be due to linkage or pleiotropic effects. The common markers lead to increase the efficiency of marker-assisted selection in plant breeding programs via simultaneously selection for several traits.
Volume 9, Issue 2 (4-2007)
Abstract
Pod length is one of the effective components on canola yield selection on the basis of which can increase not only the seed yield but also the oil yield. Molecular markers asso-ciated with long pod loci were identified in a doubled haploid population derived from a cross between the canola lines ‘Quantum’ (long pod) ‘China A’ (short pod) using RAPD and bulked segregant analysis. A molecular marker linkage map of 37 loci for this popu-lation was used to identify quantitative trait loci (QTL) controlling pod length of which two markers in two unlinked loci were selected by using an interval mapping model which explained 22% of phenotypic variation for pod length in this population. Selection for markers at two loci for increasing pod length resulted in a group of doubled haploid lines with an average 112 mm pod length that increased 15% of whole population mean. This shows that using these markers in the breeding program will enhance the breeding of long pod canola varieties.
R. Daghaghelh, H. Sabouri , H. Hosseini Moghaddm, E. Jorjani , H.a. Fallahi ,
Volume 9, Issue 3 (9-2018)
Abstract
Aims: The important achievement of genetic analysis of Quantitative trait locus (QTLs) is to facilitate the investigation of the inheritance of simple Mendelian traits. The aim of this study was mapping genes controlling morphological traits in F3 Families caused by Becher×Kavir cross in barley.
Materials and Methods: In the present experimental research, in order to map QTLs, 103 F3 families caused by Becher×Kavir cross were cultivated in a randomized complete block design with 3 replications during 2014-2015. Number of germinated seeds, during the grain filling period, plant height, peduncle length, seed weight, and harvest index were evaluated. Linkage map was prepared, using SSR, iPBS, IRAP, and ISSR marker. QTLs were identified by QGENE 4.0 software and QTL analysis was performed by composite interval mapping.
Findings: The identified QTLs justified with load score of 2.007, 8.6% of variance of phenotype germinated seed number, score of 22.2, 9.5% variance of phenotype grain filling period, score of 2.74, 1.16% of variance of plant height, score of 2.19, 9.3% of the variance of the peduncle length, the score of 2.04, 8.7% of variance of the seed weight, and with the scores of 2.38, 2.38, and 2.16 justified 10.1, 10.1, and 9.2% of the variance of the harvest index, respectively.
Conclusion: There are one QTL on chromosome 6 and ISSR38-4 closely marker for number of germinated seeds, one QTL on chromosome 7 in iPBS2076-6-iPBS2085-1 distance of marker for during the grain filling period, one QTL on chromosome 2 in iPBS2083-3-HVBKASI distance of marker for plant height, one QTL on chromosome 6 and ISSR38-4 closely marker for peduncle length, one QTL on chromosome 3 in iPBS2075-5-ISSR38-7 distance of marker for seed weight, and 3 QTLs for harvest index, respectively.
Volume 10, Issue 3 (7-2008)
Abstract
Heat stress is a major environmental stress limiting wheat productivity in most cereal
growing areas of the world. In order to map and characterize quantitative trait loci controlling
heat tolerance, 144 recombinant inbred lines deriving from the cross of Kauz and
MTRWA116 were assessed in a greenhouse and growth chamber at 35°C. One hundred
and sixty six SSR and 3 AFLP markers were used to construct a linkage map containing
18 linkage groups and covering 16 chromosomes of wheat. Using the composite interval
mapping method, three QTLs were detected for heat tolerance and measured by the
Fischer susceptibility index, on chromosomes 1B, 5B and 7B. The alleles of both parents
contributed to heat tolerance. A large amount of explained phenotypic variances and
small confidence intervals indicate that the linkage information between markers and
QTLs could easily be used in breeding for heat tolerance.
Volume 14, Issue 5 (9-2012)
Abstract
In order to locate the QTLs for plant height, peduncle length, and heading date, a set of 107 wheat doubled haploid (DH) lines derived from the cross Fukuho-komugi× Oligoculm was grown during the growing seasons of 2004 and 2005. A total of 36 QTLs were identified based on composite interval mapping (CIM) approach. All detected plant height QTL’s were stable over the two years. QTLs located near RhtD1 (chromosome 4D) and in the Xta556-RhtB1 interval (chromosome 4B) accounted for, respectively, 40.1% and 28.9% of plant height variation in 2004 and 30.7% and 26.36% in 2005. The other two QTLs identified for plant height were located near Xcfd53 and Xwmc25a loci on chromosome 2D. The results of composite interval mapping indicated that all detected QTLs for peduncle length were coincident with plant height QTLs. Of the most important heading date QTLs, the only stable one over years was located in the Xcfd53-Xbarc168 interval on chromosome 2D and accounted for 34.05% and 31.9% of heading date variation in 2004 and 2005, respectively. The Xbarc168-Xgwm484 interval (LOD> 8.3) carried the other important QTL for heading date in 2004. In general, based on expression of stable and major effect QTLs in present study, it is possible to increase efficiency of marker assisted selection for the traits in breeding programs.
Volume 16, Issue 6 (11-2014)
Abstract
Salinity stress is a major limitation in wheat production. The lack of economically viable methods for screening salinity tolerance in field is an obstacle to breeders. In this study a population of 254 recombinant inbred lines (RILs), derived from a cross between Roshan × Sabalan was assessed in glasshouse during the seedling phase in order to identify quantitative trait loci (QTLs) for salinity related traits. A genetic linkage map was constructed from 239 markers, namely, 225 Diversity Arrays Technology markers (DArTs) and 14 simple sequence repeats (SSRs) which spanned a total of 1,099.7cM. A total of 31 QTLs for salinity tolerance were identified on 13 chromosomes, contributing more than 50% of the total phenotypic variation. The frequency of Roshan and Sabalan alleles were high at loci on different homeologous groups. Most of the detected QTLs were located on chromosomes 3B, 5B among the 13 chromosomes. Two QTL related fresh weight and height of shoot were detected on 1A and 3A which explained 18% and 12.9% of the total phenotypic variation respectively. Roshan (salt tolerance) alleles were associated with an increase in all traits under both control and stress conditions. SSR markers gwm626 and gwm540 (on chromosomes 6B and 5B, respectively) were tightly linked with different QTLs under control and stress conditions, and explained 21.1% and 8.1% of the total phenotypic variance, respectively. Some of these QTL mapped to genomic regions previously associated with salt tolerance in wheat.
Volume 17, Issue 1 (1-2015)
Abstract
Basal stem rot caused by Sclerotinia sclerotiorum (Lib.) de Bary is one of the most important diseases of sunflower. Quantitative trait loci (QTL) implicated in partial resistance to two isolates of S. sclerotiorum (SSU107 and SSKH41) were investigated using F9 recombinant inbred lines (RILs) from the cross between sunflower parental lines PAC2 and RHA266. Experiments were conducted in completely randomized design with 3-6 replications under controlled conditions. The reaction of genotypes to basal stem rot disease was evaluated by measuring the percentage of necrosis area three days after inoculation. Combined analysis of experiments showed significant interactions between sunflower genotypes and S. sclerotiorum isolates suggesting that partial resistance to S. sclerotiorum should be isolate-specific in sunflower. QTLs were mapped using an updated high-density SSR and SNP linkage map. The map consisted of 210 SSRs and 11 gene-derived markers placed in 17 linkage groups (LGs). The total map length was 1,653.1 cM with a mean density of 1 marker per 7.44 cM. A total of 14 QTLs were detected for partial resistance to two isolates. The phenotypic variance explained by QTLs (R2) ranged from 0.10 to 9.85. The sign of additive gene effects showed that favorable alleles for partial resistance to isolates came from both parents. Six QTLs were common between two isolates on LGs 1, 8 and 17, whereas the others were specific for each isolate. Co-localized QTLs on LG 1 were linked to the glutathione S-transferase gene (GST). The co-localized QTLs for partial resistance to basal stem rot isolates could be good candidates for marker assisted selection (MAS).
Volume 19, Issue 1 (1-2017)
Abstract
Salinity tolerance is a genetically and physiologically complex trait, controlled by Quantitative Trait Loci (QTLs). In order to map the QTLs associated with agronomic and physiological traits, 149 doubled haploid lines derived from a cross between Clipper (salt susceptible) and Sahara 3771 (salt tolerant) barley genotypes were evaluated under natural saline-stress and non-stress conditions using 14 traits. QTL analysis was performed based on the composite interval mapping method, using the genetic linkage map consisting of 517 molecular markers which spanned a total of 1502.4 cM. A total of 78 QTLs for days to heading, relative water content, chlorophyll content, plant height, spike length, days to maturity, biomass, grain yield, harvest index, grain number per spike, 1,000-kernel weight, Na+, K+ concentrations and K+/Na+ ratio, were determined, with 40 and 38 QTLs under normal and salinity environments, respectively. Most of the detected QTLs were located on chromosome 2H. The phenotypic variation explained by individual QTLs ranged from 3.3 to 68.6%. A major QTL was identified at both saline-stress and non-stress conditions in the vicinity of Vrs1 on chromosome 2H, related to biomass, grain number per spike, 1,000 kernel weight, plant height and grain yield. This QTL may be useful in the barley breeding programs for improving salt tolerance by marker-assisted selection. Furthermore, some stable QTLs, were identified for days to heading, biomass, spike length, grain number per spike, 1,000 kernel weight, and K+ content which can be regarded as promising QTLs for breeding purposes.
