جستجوی مقالات مرتبط با کلیدواژه "نقشه یابی ارتباطی" در نشریات گروه "بیوتکنولوژی و ژنتیک گیاهی"

In order to identify loci controlling seedling morpho-physiologic characteristics in 88 bread wheat cultivars, a greenhouse experiment based on simple alpha lattice was conducted under both normal and 120 mM (12 ds/m) salt stress condition of the Faculty of Agriculture, Urmia University in 2020-2021 cropping season. Chlorophyll a, b and carotenoid content, proline, plant fresh and dry weight, plant height and leaf relative water content (RWC), Na+, K+ and K+/Na+ concentrations were measured. After genotyping by sequencing with Ion Torrent technology and removal of SNPs with more than 20% of missing data and minor allele frequency less than 5%, a total of 5869 SNP markers were identified. Based on association mapping with the mixed linear model (MLM) method, a total of 25 marker-trait associations were detected under normal conditions. The A and D genomes had the highest and lowest number of significant marker-trait associations (MTAs). Among the studied traits under normal conditions, chlorophyll a had the highest number of MTAs on 1A, 3B, 3D, 5B, 7A chromosomes with eight MTAs. A total of 21 MTAs were identified under salt stress conditions which the genome B and D had the highest and lowest number of MTAs, respectively. Five MTAs were identified for plant fresh weight, which were located on chromosomes 4A and 6B. The results of this study provide valuable information about the loci associated with the studied traits, which can be used in marker assisted selection in wheat breeding programs after confirmation in biparental populations and additional experiments.

Rice grain discoloration disease is emerging as a major threat in improved and late ripening varieties in the north of Iran that deteriorates grain quality and physical properties. Breeding for disease resistance is the preferred strategy to manage grain discoloration. An important application of molecular markers in plant systems involves improvement in the efficiency of conventional plant breeding by carrying out indirect selection through molecular markers linked to the traits of interest. In this context, association analysis was used to identify molecular markers associated with grain discoloration resistance in rice genotypes in this study. 

In this study, resistance of 94 rice genotypes (Iranian landrace and improved varieties and exotic genotypes) to grain discoloration disease was evaluated during 2017 and 2018.Genotyping was done using 128 pairs of polymorphic microsatellite markers on 94 genotypes of rice. Then association analysis was conducted through general linear model (GLM) and mixed linear model (MLM) by using TASSEL software.

Phenotypic analysis showed that there is high diversity in the studied genotypes for resistance to grain discoloration disease. The model-based structure analysis classified rice genotypes into two sub-populations. In association analysis based on GLM and MLM models, 12 and 3 QTLs showed significant relations after considering Bonferroni correction with grain discoloration in two years, respectively.

Both GLM and MLM detected 3 markers (RM242, RM5709 and RM5955) associated with grain discoloration resistance in both 2017 and 2018, suggesting that these markers can be used in rice breeding programs like marker-assisted selection (MAS).

The phenotypic diversity of many important traits in plants is influenced by several loci, environmental factors and their interactions. Association mapping is one of the methods proposed in recent decades for genetic study and detection of quantitative trait loci (QTLs). Association mapping was used in human genetics and qualitative traits (such as diseases), but recently its use is increasing in the plant science because of advances in high throughput genomic technologies, interests in identifying novel and superior alleles, and improvements in statistical methods. Association mapping through linkage disequilibrium analysis is a purposeful method for identifying marker alleles and quantitative traits association. Unlike linkage mapping, this method identifies the association between phenotypic and polymorphic diversity in the genome by exploiting the diversity of natural populations and taking into account all the events that occurred during the evolution and is a promising approach for overcoming the limitations of linkage mapping. Despite association mapping has high statistical power, the application of this method in structured populations, species with low level of linkage disequilibrium and in traits controlled by rare alleles is complicated and difficult. In this review, we will present a comprehensive view, its application in population, current status and limitation of association mapping in plant science.

In order to detect QTLs for yield and some important agronomic traits via association mapping, 100 cultivars of winter barley (Hordeum vulgare) were evaluated in a lattice design with two replications. Yield, kernel per spike, thousand kernel weight, heading date, harvest index and plant height were measured. The population was genotyped using 3964 SNPs with minor allele frequency (MAFs) more than 10 percent. Molecular analysis of the population structure appeared two subpopulations consistent with ear row number. Average LD was observed to decay with distance increase and in the subpopulations was more than of that in the whole genome. Using a mixed linear model with kinship for controlling spurious LD effects, a total of 103 significant marker trait associations were found. 47 of the significant associations had previously been reported and 56 QTLs were reported for the first time. SNP_3660 linked with the yield and SNP_1432 associated with the kernel per spike, the thousand kernel weight and the spike morphology (two rows and six rows) had maximum -Log P and could be considered for marker assisted selection. This study showed that association mapping is a powerful tool for quantitative trait loci localization.

This study was conducted to identify markers associated with some kernel traits in bread wheat in two separate experiments under field and laboratory. One hundred wheat genotypes were evaluated in an alpha lattice experimental design with two replications. Grain hardness¡ seed length¡ seed width and thousand kernel weights were measured. Association mapping was performed based on 96 unlinked and 22 SSR QTL linked markers¡ using structure and Tassel software. Correction for population structure was performed using genome wide SSR markers so that genotypes were divided into six sub-populations. Totally¡ 35 SSR markers linked to traits were detected; eight of them being QTL linked markers and other markers that were linked to traits¡ were used to investigate population structure. The QTLs linked markers were as follows: Chromosomes 5B¡ 5D and 6D had three QTL for grain hardness. Nine QTLs were detected on chromosomes 1A¡ 1B¡ 2A¡ 2B¡ 2D¡ 5B¡ 5D¡ 6D and 7B for kernel length¡ kernel width and thousand kernel weights. The results of this study demonstrate that association mapping is a useful approach to complement and enhance previous QTL information for marker-assisted selection in wheat.