Wheat Microsatellite Research Articles

Authentication of a food product based on DNA analysis of an added natural biological tracer: Testing the application to dry cured hams

Food authenticity is crucial for all value chains, including many meat products. Various methods have been developed to authenticate meat products based on the intrinsic DNA information of the animals from which the products originated. In this study, we propose an alternative method of authentication based on DNA analysis of a biological tracer added to the product. To demonstrate its effectiveness, we conducted a pilot study focused on dry-cured hams that were authenticated using genetically characterised wheat flours, obtained from different accessions. The study consisted of three main steps: first, we analysed 23 wheat accessions using random amplified polymorphic DNA assays and seven wheat microsatellites to assess the accession homogeneity/homozygosity and establish accession specific microsatellite fingerprinting; next, we tested, as a proof-of-concept, the feasibility of using genetically characterised wheat flours as natural tracers when mixed with lard (used to cover the skin-free part of the legs) and ink (used to label the legs), which are routinely applied in ham production; finally, we tested the possibility of authenticating hams by retrieving DNA information from the applied matrices (lard and ink mixed with flour) on the legs that were cured and ripened for 16 months. The DNA fingerprinting was consistent throughout all evaluation stages enabling the authentication of the marked hams. One advantage of this system is that the tracer (and its DNA profile) is known only to the authentication system managers. This approach can be adapted to authenticate many other food products.

Evaluation of Agronomic Performance and Genetic Diversity Analysis Using Simple Sequence Repeats Markers in Selected Wheat Lines

Crop improvement is the fundamental goal of plant biologists, and genetic diversity is the base for the survival of plants in nature. In this study, we evaluated 20 wheat lines for morphological and genetic diversity using eight simple sequence repeats markers from Wheat Microsatellite Consortium (WMC). Morphologically, variations were observed among all of the different wheat lines for the studied trait except for single spike weight. The highest values for different agronomic traits were recorded for the different wheat lines. The maximum days to heading were recorded for Borlaug-16 (128.3 ± 2.52 days). Similarly, days to maturity were recorded and were highest in Markaz-19 (182.3 ± 5.13 days), followed by Borlaug-16 (182.0 ± 4.58 days). The highest plant height was observed for Zincol-16 (122.3 ± 2.51 cm), followed by Markaz-19 (120.0 ± 14.79 cm) and Borlaug-16 (119.7 ± 6.8 cm). The productivity measured by 100-grain weight was highest in the case of Zincol-16 (84.0 ± 7.5 g). In contrast, wheat lines Shahkar, Sehar, and Farid-6 showed the lowest values for the traits tested. The results of genetic diversity revealed a total number of 16 alleles at eight SSR markers with an average of 2.00 ± 0.534 alleles per locus. Out of eight SSR markers, one marker (WMC105) was monomorphic, and six were dimorphic, showing two alleles at each locus. The maximum number of alleles (3) was observed for marker WMC78, in which genotypes AC and AA were predominantly found in high-yielding lines Borlaug-2016 and Zincol-2016 that were distantly related to other varieties. Zincol-2016 was also agronomically distinct from the rest of the 19 wheat lines. The results obtained from this study may be of importance for the scientific community to further explore the underlying genetic polymorphism associated high yielding varieties using marker-assisted selection for sustainable agriculture.

Polymorphism in the short arm of 1R rye chromosomes in wheat lines with 1RS.1BL translocation and 1R(1B) substitution from different sources

Aim. The short arm of 1R rye (Secale cereale L.) chromosome is widely used in the breeding of bread wheat (Triticum aestivum L.), in particular 1RS.1BL, to introsgress genes of resistance to leaf (Lr26), stem (Sr31), striped (Yr9) rusts, as well as powdery mildew (Pm8); 1RS.1AL carries Gb2/Gb6 resistance genes to the wheat aphid (Schizaphis graminum Rondani), powdery mildew (Pm17), and the Cmc4 resistance gene to the Aceria tosichella Koifer mite, which is a vector for spreading of wheat mosaic virus. The aim of the research is to reveal molecular genetic polymorphisms of short arm rye 1RS chromosomes of different origins in bread wheat lines with 1RS.1BL translocation or 1R(1B) substitution from different sources. Methods. Genetic polymorphism of lines was analyzed by using PCR with a number of rye and wheat microsatellite markers. Results. It was shown that the CWXs line has a recombinant 1RS arm that contains the chromosomes parts of 1RS of the parental lines H242/97-2 and H273/97, due to crossover event, which led to the recombination of marked loci. Conclusions. Molecular genetic polymorphism has been reviled in 1RS.1BL translocations and 1R substituted rye chromosomes of different origins in H242/97-2, CWXs, H273/97, PavonMA1, Salmon lines, as there are different alleles present at loci: Xscm9, Xtsm422, Xgwm752, Xgwm18, Taglgap. Keywords: polymorphism, 1RS.1BL translocation, PCR analysis, microsatellites markers.

Molecular characterization and genetic diversity in some Egyptian wheat (Triticum aestivum L.) using microsatellite markers

Wheat (Triticum aestivum L.) is the most important and strategic cereal crop in Egypt and has many bread wheat varieties. Seventeen Egyptian bread wheat varieties used in this study with a set of sixteen wheat microsatellite markers to examine their utility in detecting DNA polymorphism, estimating genetic diversity and identifying genotypes. A total of 190 alleles were detected at 16 loci using 16 microsatellite primer pairs. The number of allele per locus ranged from 8 to 20, with an average of 11.875. The polymorphic information content (PIC) and marker index (MI) average values were 0.8669, 0.8530 respectively. The (GA) n microsatellites were the highest polymorphic (20 alleles). The Jaccard's Coefficient for genetic similarity was ranged from 0.524 to 0.109 with average of 0.375. A dendrogram was prepared based on similarity matrix using UPGMA algorithm, divided the cultivars into two major clusters. The results proved the microsatellite markers utility in detecting polymorphism due to the discrimination of cultivars and estimating genetic diversity.

RETRACTED: Characterization of wheat (Triticum aestivum L.) genotypes unraveled by molecular markers considering heat stress

Abstract The current study focuses and emphasis on the potential of heat stress to negatively affect crop physiology. Here, we have screened 19 wheat (Triticum aestivum L.) genotypes for their tolerance of heat stress. Significant differences were observed among the genotypes for all the traits under consideration. Exploitable extent of genetic variability amongst the entries was present as revealed by considerably higher estimates of mean %. On the basis of Heat susceptibility Index, Halna, Mon’s Ald’s, genotypes Cuo/79/Prulla and K 307 were identified as heat-tolerant whereas SAWSN 3041, SAWSN 3101 and K 0583 were identified as heat-susceptible. The 17 wheat microsatellite markers were capable of detecting 89 alleles with an average of 4.6 alleles per locus. Polymorphism Information Content value ranged from 0.16 for the primer XGWM 516 to 0.83 for DUPW 117 with an average of 0.60. A perusal of similarity coefficients clearly reflected that a very high degree of similarity exists between wheat variety Mon’s Ald’s and SAWSN 3101 (0.70). On the other hand, the two most distantly related cultivars were found to be AKAW 4008 and PBW 343 (0.034). BARC 4, BARC 170, BARC 311, PSP 3058, WHE014.H04 and GWM 458 were strongly associated with the heat tolerance for traits TGW and BARC 311 was strongly associated with terminal heat tolerance for number of grains/plant respectively. Considering all the parameters it is adjudged that relatively stable genotypes may be evaluated at various agro climatic regions for grain yield and heat tolerance along with other contributing characters and ideal plant type.

Identification of microsatellite loci based on BAC sequencing data and their physical mapping into the soft wheat 5B chromosome

The shortage of polymorphic markers for the regions of the wheat chromosomes that encode commercially valuable traits determines the need for studying the wheat microsatellite SSR loci. In this work, SSR markers for individual regions of the short arm of soft wheat chromosome 5B (5BS) were designed based on the sequence data obtained from BAC clones, and regions of the corresponding chromosome were saturated with these markers. Totally, 130 randomly selected BAC clones from 5BS library were sequenced using the IonTorrent platform and assembled in contigs using MIRA software. The assembly characteristics (N50 = 4136 bp) are comparable to the recently obtained data for wheat and related species and are acceptable for the identification of the microsatellite loci. The algorithm utilizing the properties of complex decompositions in the sliding-window mode was used to detect DNA sequences with a repeat unit of 2–4 bp. Analysis of 17770 contigs with a total length of 25879921 bp allowed for the design of 113, 79, and 67 microsatellite SSR loci with a repeat unit of 2, 3, and 4 bp, respectively. SSR markers with a motif of 3 bp were tested using nullitetrasomic lines of Chinese Spring wheat homoeologous group 5. In total, 21 markers specific for chromosome 5B were identified. Eight of these markers were mapped into the distal region of this chromosome (bin 5BS6) using a set of Chinese Spring deletion lines for 5BS. Eight and four markers were mapped to the interstitial region (bins 5BS5 and 5BS4, respectively). One marker was mapped to a pericentromeric bin. Comparative analysis of the distribution of trinucleotide microsatellites over wheat chromosome 5B, and in different cereal species, suggests that the (AAG) n repeat proliferates and is conserved during the evolution of cereals.

Identification of microsatellite loci according to BAC sequencing data and their physical mapping to the bread wheat 5B chromosome

The shortage of polymorphic markers for the regions of wheat chromosomes that encode commercially valuable traits determined the need for studying wheat microsatellite loci. In this work, SSR markers for individual regions in the short arm of bread wheat chromosome 5B (5BS) were designed based on sequencing data for BAC clones, and the regions of the corresponding chromosome were saturated with these markers. Totally, 130 randomly selected BAC clones from the 5BS library were sequenced on the Ion Torrent platform and assembled in contigs using MIRA software. The assembly characteristics (N50 = 4 136 bp) are comparable to the recently obtained data for wheat and relative species and acceptable for identification of microsatellite loci. An algorithm utilizing the properties of complexity decompositions in he sliding-window mode was used to detect DNA sequences with a repeat unit of 2–4 bp. Analysis of 17 770 contigs with the total length of 25 879 921 bp allowed for designing 113, 79, and 67 microsatellite (SSR) loci with a repeat unit of 2, 3, and 4 bp, respectively. The SSR markers with a motif of 3 bp were tested using nullitetrasomic lines of Chinese Spring wheat homoeologous group 5. Thus, 21 markers specific for chromosome 5B were detected. Eight of these markers were mapped to the distal region of this chromosome (bin 5BS6) using a set of Chinese Spring deletion lines for 5BS. Eight and four markers were mapped to the interstitial region (bins 5BS5 and 5BS4, respectively). One marker was mapped to a pericentromeric bin. A comparative analysis of the distribution of trinucleotide microsatellites over wheat chromosome 5B and in different cereal species suggests that the (AAG)n repeat has proliferated and has been maintained during the evolution of cereals.

Genetic mapping and inheritance of Russian wheat aphid resistance gene in accession IG 100695

AbstractThe Russian wheat aphid (RWA), Diuraphis noxia (Kurdjumov), is an important pest of small‐grain cereals, particularly wheat, worldwide. The most efficient strategy against the RWA is to identify sources of resistance and to introduce them into susceptible wheat genotypes. This study was conducted to determine the mode of inheritance of the RWA resistance found in ICARDA accession IG 100695, to identify wheat microsatellite markers closely linked to the gene and to map the chromosomal location of the gene. Simple sequence repeat (SSR) marker scores were identified in a mapping population of 190 F2 individuals and compared, while phenotypic screening for resistance was performed in F2 : 3 families derived from a cross between ‘Basribey’ (susceptible) and IG 100695 (resistant). Phenotypic segregation of leaf chlorosis and rolling displayed the effect of a single dominant gene, temporarily denoted Dn100695, in IG 100695. Dn100695 was mapped on the short arm of chromosome 7D with four linked SSR markers, Xgwm44, Xcfd14, Xcfd46 and Xbarc126. Dn100695 and linked SSR markers may be useful for improving resistance for RWA in wheat breeding.

Comparison of similarity coefficients used for cluster analysis based on SSR markers in sister line wheat cultivars

The objective of this study was to compared fourteen different similarity coefficients and their influence in sister line wheat cultivars clustering. Seventeen sister cultivars developed from two crosses were used and fingerprinted with 19 wheat microsatellite markers. Comparisons among the similarity coefficients were made using the Sperman correlation analysis, dendogram evaluation (visual inspection and consensus fork index - CIc), projection efficiency in a two-dimensional space, and groups formed by the Tocher optimization procedure. The Sperman correlation coefficients among the fourteen similarity coefficients were all high showing a strong association between them. The correlation coefficient between Dice and Kulczinski and Ochiai I as well as between Hamann and Simple matching and between Kulczinski and Ochiai I was equal to 1. Although visual estimation of the dendograms shows almost identical clustering structures, CIc indexes indicate that all coefficients are not identical.

Molecular diversity analysis in Wheat genotypes using SSR markers

Molecular diversity of the seven wheat ( Triticum aestivum L.) genotypes was evaluated using 50 SSR primers. Genetic distances were calculated using unweighted pair group of arithmetic mean (UPGMA) procedure. A high degree of genetic polymorphism was observed among the wheat varieties with average genetic polymorphism 70%. SSR diversity data was generated using above primers and a total of 114 alleles were detected with an average of 2.71 alleles per locus. The number of alleles per locus ranged from 2 to 6 and the percent of polymorphism ranged from 20% for the Xwmc254 to 100% for the Xbarc26. The average genetic diversity based on SSR markers was 0.465 with a range of 0.037- 0.892. Our results suggested that the classification based on genotypic markers of these wheat genotypes would be useful for wheat breeders to plan crosses for positive traits. The results obtained suggested that the wheat microsatellite markers could be used to distinguish wheat genotypes and to estimate genetic diversity. The present study also indicates that microsatellite markers permit the fast and high throughout fingerprinting of accessions from a varieties collection in order to assess genetic diversity.

Molecular-cytogenetic analysis of triticale and wheat lines with introgressions of the tribe Triticeae species genetic material

There are a number of problems in selection of cultivated cereals associated with the requirements to create forms with resistance to diseases, pests and unfavorable environmental conditions. The genetic diversity of genes for resistance to biotic and abiotic stresses can be increased by means of the gene pool of wild and cultivated wheat relatives. To improve agronomic traits in cereals, we have developed common wheat hybrid lines T. aestivum/ T. durum, T. aestivum/ T. dicoccoides and triticale lines by crossing hexaploid triticale with common wheat forms with the substitution of genome D for the geno­me of diploid Aegilops species. The aim of the study was to identify the lines of common wheat and hexaploid triticale with alien introgression using cytological and molecular-genetic analyses and evaluation of their cytological stability. Comparative analysis of the structure of chromosomes by GISH and FISH methods, microsatellite- and chromosome-specific markers revealed that hybridization of triticale with genome-substitution forms of wheat leads to the reorganization of the genome, including both the introgression of foreign material and wheat chromosome rearrangements, which lead to new combinations of genetic loci. The efficiency of wheat microsatellite markers to characterize of the T. aestivum/ T. durum, T. aestivum/ T. dicoccum interspecific hybrid lines was shown. From 4 to 12 translocations of different lengths from T. durum and T. dicoccum were identified in the chromosomes of A and В genomes in the hybrid lines. Meiotic stability of wheat and triticale hybrids was found. It creates prerequisites for preservation of alien genetic material in subsequent generations.

Molecular evidence of the haploid origin in wheat (Triticum aestivumL.) withAegilops kotschyicytoplasm and whole genome expression profiling after haploidization

Aegiolops kotschyi cytoplasmic male sterile system often results in part of haploid plants in wheat (Triticum aestivum L.). To elucidate the origin of haploid, 235 wheat microsatellite (SSR) primers were randomly selected and screened for polymorphism between haploid (2n = 3x = 21 ABD) and its parents, male-sterile line YM21 (2n = 6x = 42 AABBDD) and male fertile restorer YM2 (2n = 6x = 42 AABBDD). About 200 SSR markers yielded clear bands from denatured PAGE, of which 180 markers have identifiable amplification patterns, and 20 markers (around 8%) resulted in different amplification products between the haploid and the restorer, YM2. There were no SSR markers that were found to be distinguishable between the haploid and the male sterile line YM21. In addition, different distribution of HMW-GS between endosperm and seedlings from the same seeds further confirmed that the haploid genomes were inherited from the maternal parent. After haploidization, 1.7% and 0.91% of total sites were up- and down-regulated exceeding twofold in the shoot and the root of haploid, respectively, and most of the differentially expressed loci were up/down-regulated about twofold. Out of the sensitive loci in haploid, 94 loci in the shoot, 72 loci in the root can be classified into three functional subdivisions: biological process, cellular component and molecular function, respectively.

Efficiency of the different marker systems for estimation of distinctness between sister line wheat cultivars

A set of 42 winter wheat cultivars developed from nine populations were evaluated for distinctness. Three marker systems: morphological markers, gliadin allele profiles and microsatellites were used to analyze distinctness between sister cultivars. The morphological based distinctness tests for wheat are based on a crop-specific set of characters that comply with UPOV guidelines. The morphological markers were quite informative although they were not capable to estimate the distances/distinctness between two pair of sister cultivars Evropa 90 and Evropa and Novosadska rana 3 and Novosadska rana 2. The gliadins allele profiles were the least efficient to estimate distinctness between sister line cultivars. This system was not capable to distinguish even cultivars developed from different populations. Sister line wheat cultivars were fingerprinted with 19 wheat microsatellites markers. A total of 106 alleles were detected at 19 wheat microsatellite loci, resulting in an average allele number per marker of 5.6. The number of markers was sufficient to distinguish among most sister line cultivars. Only one pair of sister cultivars, Loznicanka and Kosovka, derived from the same cross could not be distinguished. Comparing all marker systems to evaluate distinctness of sister line wheat cultivars the most efficient was microsatellite markers while gliadin allele profiles was the least efficient. Correlations between matrices based on pedigree data and morphological marker, gliadin profiles and microsatellites were significant but not large.

English

The genetic diversity of a set of 21 hexaploid wheat germplasm from the National Agronomic Institute of Tunisia were investigated by applying 26 agro morphological traits and 10 wheat microsatellites molecular markers (Simple Sequence Repeat). The morphological variability was analyzed using the Principal Component Analysis (PCA) and the cluster analysis based on ward’s method and square Euclidean distance. Eighteen microsatellites primer pairs were tested for all genotypes, among them 10 primers generated polymorphic and reproducible profiles. They revealed a total of 414 reducible bands among which 373 were polymorphic. The polymorphic information content (PIC) values per locus varied from 0,33 to 0,94 with an average of 0,72. Genetic similarity values between genotypes, calculated by the molecular derived data, were used to produce a dendrogram. The genotypes were clustered in four clear groups according to their origin, pedigree and in some cases to phenotypic characters similarities.

Assessing genetic diversity of Egyptian hexaploid wheat (Triticum aestivum L.) using microsatellite markers

Genetic diversity was investigated in a set of thirty-three hexaploid wheat genotypes originated from Egypt, using 17 wheat microsatellites, representatives of fifteen wheat chromosomes. In total, ninety-five alleles were detected among Egyptian wheats. For 17 polymorphic microsatellite markers, the number of alleles per locus varied from 3 for Xgwm261-2DS, Xgwm3-3DL and Xgwm631-7AS to 11 for Xgwm437-7DL, with a mean of 5.59 alleles per locus. The highest average number of alleles per locus was detected in the B genome with 6.00, compared to 5.67 and 5.00 for genomes D and A, respectively. The highest and the lowest average number of alleles per locus among the wheat homoeologous groups were observed in group 7 and 3 with 7.00 and 4.00, respectively. Gene diversity for 17 microsatellites loci varied from 0.339 for Xgwm631-7AS to 0.845 for Xtaglgap-1BS with an average of 0.653. However, the gene diversity for three genomes A, B and D was 0.549, 0.718 and 0.674, respectively. A significant correlation coefficient between gene diversity and the number of alleles per locus, genomes and homoeologous groups was high, r = 0.649, 0.988 and 0.272 (P < 0.01), respectively. The gene diversity increased as the number of alleles increased. Cluster analysis was conducted based on microsatellites data. Five groups can be distinguished by truncating the dendrogram at genetic similarity (gs) value of 0.48. The present study indicated the presence of high diversity in Egyptian wheat genotypes.

Microsatellite-based assessment of genetic diversity in stripe rust resistant NUWYT candidate lines

Stripe rust is one of the most devastating diseases, caused by Puccinia striiformis f. sp. tritici, affecting a huge amount of wheat crops worldwide. In this study, the genetic diversity of 16 National Uniform Wheat Yield Trial (NUWYT) candidate lines was evaluated by using 22 screened microsatellite markers. These lines were found resistant for stripe rust at adult plant stage. These wheat microsatellite markers identified a total of 38 alleles, with an average of 2.3 alleles per microsatellite locus. The number of alleles ranged from one to five alleles and the highest number of alleles were associated with B genome (25), as compared to D (11) and A (2) genomes. The allelic polymorphism index content (PIC) reflecting the gene diversity of these microsatellite markers ranged from 0.00 to 0.66, with an average of 0.27. The maximum PIC value of 0.66 was observed for xgwm 159-5B and 0.64 for xgwm 413-1B. The gene diversity ranged from 0.00 to 0.71, with an average of 0.30. The genetic similarity matrix was used to construct a dendrogram and the cluster analysis was performed by the use of unweighted pair-group method with arithmetic average algorithm. This divided the entire 16 candidate lines into three main clusters on the basis of their similarity. Our results indicate that the genetic diversity among the 16 candidate NUWYT lines was very narrow.

Mapping QTL for resistance to eyespot of wheat in Aegilops longissima

Eyespot is an economically important disease of wheat caused by the soilborne fungi Oculimacula yallundae and O. acuformis. These pathogens infect and colonize the stem base, which results in lodging of diseased plants and reduced grain yield. Disease resistant cultivars are the most desirable control method, but resistance genes are limited in the wheat gene pool. Some accessions of the wheat wild relative Aegilops longissima are resistant to eyespot, but nothing is known about the genetic control of resistance. A recombinant inbred line population was developed from the cross PI 542196 (R) × PI 330486 (S) to map the resistance genes and better understand resistance in Ae. longissima. A genetic linkage map of the S(l) genome was constructed with 169 wheat microsatellite markers covering 1261.3 cM in 7 groups. F(5) lines (189) were tested for reaction to O. yallundae and four QTL were detected in chromosomes 1S(l), 3S(l), 5S(l), and 7S(l). These QTL explained 44 % of the total phenotypic variation in reaction to eyespot based on GUS scores and 63 % for visual disease ratings. These results demonstrate that genetic control of O. yallundae resistance in Ae. longissima is polygenic. This is the first report of multiple QTL conferring resistance to eyespot in Ae. longissima. Markers cfd6, wmc597, wmc415, and cfd2 are tightly linked to Q.Pch.wsu-1S ( l ), Q.Pch.wsu-3S ( l ), Q.Pch.wsu-5S ( l ), and Q.Pch.wsu-7S ( l ), respectively. These markers may be useful in marker-assisted selection for transferring resistance genes to wheat to increase the effectiveness of resistance and broaden the genetic diversity of eyespot resistance.

Isolation and chromosomal localization of new MITE-like sequences from Secale

A species-specific DNA sequence (marker) that can detect the presence of Secale cereale chromatin in common wheat background was developed by using wheat microsatellite primer Xgwm614. One rye-specific DNA amplified fragment of 416bp (pSa614416) was obtained from Secale africanum and a wheat - S. africanum amphiploid. The primer Xgwm614 also gave rise to specific bands in all Chinese Spring-Imperial rye addition lines 1R to 7R. Sequence analysis revealed that pSa614416 was strongly homologous to a miniature inverted transposable element (MITE) stowaway-like element. Results of fluorescence in situ hybridization showed that the signal of pSa614416 was distributed along all S. cereale. cv Jingzhou chromosomes, but the signal strengths were unbalanced on the seven rye genome chromosomes. This repetitive element may be useful as a molecular marker for the introgression of rye germplasm into the wheat genome.

Development and molecular characterization of wheat –Aegilops kotschyiaddition and substitution lines with high grain protein, iron, and zinc

Over two billion people, depending largely on staple foods, suffer from deficiencies in protein and some micronutrients such as iron and zinc. Among various approaches to overcome protein and micronutrient deficiencies, biofortification through a combination of conventional and molecular breeding methods is the most feasible, cheapest, and sustainable approach. An interspecific cross was made between the wheat cultivar 'Chinese Spring' and Aegilops kotschyi Boiss. accession 396, which has a threefold higher grain iron and zinc concentrations and about 33% higher protein concentration than wheat cultivars. Recurrent backcrossing and selection for the micronutrient content was performed at each generation. Thirteen derivatives with high grain iron and zinc concentrations and contents, ash and ash micronutrients, and protein were analyzed for alien introgression. Morphological markers, high molecular weight glutenin subunit profiles, anchored wheat microsatellite markers, and GISH showed that addition and substitution of homoeologous groups 1, 2, and 7 chromosomes of Ae. kotschyi possess gene(s) for high grain micronutrients. The addition of 1U/1S had high molecular weight glutenin subunits with higher molecular weight than those of wheat, and the addition of 2S in most of the derivatives also enhanced grain protein content by over 20%. Low grain protein content in a derivative with a 2S-wheat translocation, waxy leaves, and absence of the gdm148 marker strongly suggests that the gene for higher grain protein content on chromosome 2S is orthologous to the grain protein QTL on the short arm of group 2 chromosomes.

Genome-wide identification of QTL conferring high-temperature adult-plant (HTAP) resistance to stripe rust (Puccinia striiformis f. sp. tritici) in wheat

High-temperature adult-plant (HTAP) resistance to stripe rust (caused by Puccinia striiformis f. sp. tritici) is a durable type of resistance in wheat (Triticum aestivum L.). This study identified quantitative trait loci (QTL) conferring HTAP resistance to stripe rust in a population consisting of 169 F8:10 recombinant inbred lines (RILs) derived from a cross between a susceptible cultivar Rio Blanco and a resistant germplasm IDO444. HTAP resistance was evaluated for both disease severity and infection type under natural infection over two years at two locations. The genetic linkage maps had an average density of 6.7 cM per marker across the genome and were constructed using 484 markers including 96 wheat microsatellite (SSR), 632 Diversity Arrays Technology (DArT) polymorphisms, two sequence-tagged-site (STS) from semi-dwarf genes Rht1 and Rht2, and two markers for low molecular-weight glutenin gene subunits. QTL analysis detected a total of eight QTL significantly associated with HTAP resistance to stripe rust with two on chromosome 2B, two on 3B and one on each of 1A, 4A, 4B and 5B. QTL on chromosomes 2B and 4A were the major loci derived from IDO444 and explained up to 47 and 42% of the phenotypic variation for disease severity and infection type, respectively. The remaining five QTL accounted for 7–10% of the trait variation. Of these minor QTL, the resistant alleles at the two QTL QYrrb.ui-3B.1 and QYrrb.ui-4B derived from Rio Blanco and reduced infection type only, while the resistant alleles at the other three QTL, QYrid.ui-1A, QYrid.ui-3B.2 and QYrid.ui-5B, all derived from IDO444 and reduced either infection type or disease severity. Markers linked to 2B and 4A QTL should be useful for selection of HTAP resistance to stripe rust.