Mark Sorrells - Academia.edu (original) (raw)
Papers by Mark Sorrells
To introduce new genetic diversity into the bread wheat gene pool from its progenitor, Aegilops t... more To introduce new genetic diversity into the bread wheat gene pool from its progenitor, Aegilops tauschii (Coss.) Schmalh, 33 primary synthetic hexaploid wheat genotypes (SYN) were crossed to 20 spring bread wheat (BW) cultivars at the International Wheat and Maize Improvement Center. Modified single seed descent was used to develop 97 populations with 50 individuals per population using first back-cross, biparental, and three-way crosses. Individuals from each cross were selected for short stature, early heading, flowering and maturity, minimal lodging, and free threshing. Yield trials were conducted under irrigated, drought, and heat-stress conditions from 2011 to 2014 in Ciudad Obregon, Mexico. Genomic estimated breeding values (GEBVs) of parents and synthetic derived lines (SDLs) were estimated using a genomic best linear unbiased prediction (GBLUP) model with markers in each trial. In each environment, there were SDLs that had higher GEBVs than their recurrent BW parent for yield. The GEBVs of BW parents for yield ranged from -0.32 in heat to 1.40 in irrigated trials. The range of the SYN parent GEBVs for yield was from -2.69 in the irrigated to 0.26 in the heat trials and were mostly negative across environments. The contribution of the SYN parents to improved grain yield of the SDLs was highest under heat stress, with an average GEBV for the top 10% of the SDLs of 0.55 while the weighted average GEBV of their corresponding recurrent BW parents was 0.26. Using the pedigree-based model, the accuracy of genomic prediction for yield was 0.42, 0.43, and 0.49 in the drought, heat and irrigated trials, respectively, while for the marker-based model these values were 0.43, 0.44, and 0.55. The SYN parents introduced novel diversity into the wheat gene pool. Higher GEBVs of progenies were due to introgression and retention of some positive alleles from SYN parents.
TAG Theoretical and Applied Genetics, 2002
Genetic variation present in 64 durum wheat accessions was investigated by using three sources of... more Genetic variation present in 64 durum wheat accessions was investigated by using three sources of microsatellite (SSR) markers: EST-derived SSRs (EST-SSRs) and two sources of SSRs isolated from total genomic DNA. Out of 245 SSR primer pairs screened, 22 EST-SSRs and 20 genomic-derived SSRs were polymorphic and used for genotyping. The EST-SSR primers produced high quality markers, but had the lowest level of polymorphism (25%) compared to the other two sources of genomic SSR markers (53%). The 42 SSR markers detected 189 polymorphic alleles with an average number of 4.5 alleles per locus. The coefficient of similarity ranged from 0.28 to 0.70 and the estimates of similarity varied when different sources of SSR markers were used to genotype the accessions. This study showed that EST-derived SSR markers developed in bread wheat are polymorphic in durum wheat when assaying loci of the A and B genomes. A minumum of ten EST-SSRs generated a very low probability of identity (0.36×10 −12 ) indicating that these SSRs have a very high discriminatory power. EST-SSR markers directly sample variation in transcribed regions of the genome, which may enhance their value in marker-assisted selection, comparative genetic analysis and for exploiting wheat genetic resources by providing a more-direct estimate of functional diversity.
![Research paper thumbnail of Dispersal of durum wheat [Triticum turgidum L. ssp. turgidum convar. durum (Desf.) MacKey] landraces across the Mediterranean basin assessed by AFLPs and microsatellites](https://attachments.academia-assets.com/43991865/thumbnails/1.jpg)
](Genetic Resources and Crop Evolution, 2007
A comprehensive characterization of crop germplasm is critical to the optimal improvement of the ... more A comprehensive characterization of crop germplasm is critical to the optimal improvement of the quality and productivity of crops. Genetic relationships and variability were evaluated among 63 durum wheat landraces from the Mediterranean basin using amplified fragment length polymorphisms (AFLPs) and microsatellites markers. The genetic diversity indices found were comparable to those of other crop species, with average polymorphism information content (PIC) values of 0.24 and 0.70 for AFLP and microsatellites, respectively. The mean number of alleles observed for the microsatellites loci was 9.15. Non-metric multi-dimensional scaling clustered the accessions according to their geographical origin with the landraces from the South shore of the Mediterranean Sea closely related. The results support two dispersal patterns of durum wheat in the Mediterranean basin, one through its north side and a second one through its south side.
Drought limits cereal yields in several regions of the world and plant water status plays an impo... more Drought limits cereal yields in several regions of the world and plant water status plays an important role in tolerance to drought. To investigate and understand the genetic and physiological basis of drought tolerance in barley, differentially expressed sequence tags (dESTs) and candidate genes for the
Identification of milling and baking quality QTL in multiple soft wheat mapping populations
Theoretical and Applied Genetics, 2015
Two mapping approaches were use to identify and validate milling and baking quality QTL in soft w... more Two mapping approaches were use to identify and validate milling and baking quality QTL in soft wheat. Two LG were consistently found important for multiple traits and we recommend the use marker-assisted selection on specific markers reported here. Wheat-derived food products require a range of characteristics. Identification and understanding of the genetic components controlling end-use quality of wheat is important for crop improvement. We assessed the underlying genetics controlling specific milling and baking quality parameters of soft wheat including flour yield, softness equivalent, flour protein, sucrose, sodium carbonate, water absorption and lactic acid, solvent retention capacities in a diversity panel and five bi-parental mapping populations. The populations were genotyped with SSR and DArT markers, with markers specific for the 1BL.1RS translocation and sucrose synthase gene. Association analysis and composite interval mapping were performed to identify quantitative trait loci (QTL). High heritability was observed for each of the traits evaluated, trait correlations were consistent over populations, and transgressive segregants were common in all bi-parental populations. A total of 26 regions were identified as potential QTL in the diversity panel and 74 QTL were identified across all five bi-parental mapping populations. Collinearity of QTL from chromosomes 1B and 2B was observed across mapping populations and was consistent with results from the association analysis in the diversity panel. Multiple regression analysis showed the importance of the two 1B and 2B regions and marker-assisted selection for the favorable alleles at these regions should improve quality.
Euphytica, 2011
The Plant Genome Journal, 2011
Genomic selection (GS) uses genome-wide molecular marker data to predict the genetic value of sel... more Genomic selection (GS) uses genome-wide molecular marker data to predict the genetic value of selection candidates in breeding programs. In plant breeding, the ability to produce large numbers of progeny per cross allows GS to be conducted within each family. However, this approach requires phenotypes of lines from each cross before conducting GS. This will prolong the selection cycle and may result in lower gains per year than approaches that estimate marker-effects with multiple families from previous selection cycles. In this study, phenotypic selection (PS), conventional marker-assisted selection (MAS), and GS prediction accuracy were compared for 13 agronomic traits in a population of 374 winter wheat (Triticum aestivum L.) advanced-cycle breeding lines. A cross-validation approach that trained and validated prediction accuracy across years was used to evaluate effects of model selection, training population size, and marker density in the presence of genotype × environment interactions (G×E). The average prediction accuracies using GS were 28% greater than with MAS and were 95% as accurate as PS. For net merit, the average accuracy across six selection indices for GS was 14% greater than for PS. These results provide empirical evidence that multifamily GS could increase genetic gain per unit time and cost in plant breeding.
Advances in Agronomy, 2011
Genomic selection," the ability to select for even complex, quantitative traits based on marker d... more Genomic selection," the ability to select for even complex, quantitative traits based on marker data alone, has arisen from the conjunction of new highthroughput marker technologies and new statistical methods needed to analyze the data. This review surveys what is known about these technologies, with sections on population and quantitative genetic background, DNA marker development, statistical methods, reported accuracies of genomic selection (GS) predictions, prediction of nonadditive genetic effects, prediction in the presence of subpopulation structure, and impacts of GS on long-term gain. GS works by estimating the effects of many loci spread across the genome. Marker and observation numbers therefore need to scale with the genetic map length in Morgans and with the effective population size of the population under GS. For typical crops, the requirements range from at least 200 to at most 10,000 markers and observations. With that baseline, GS can greatly accelerate the breeding cycle while also using marker information to maintain genetic diversity and potentially prolong gain beyond what is possible with phenotypic selection. With the costs of marker technologies continuing to decline and the statistical methods becoming more routine, the results reviewed here suggest that GS will play a large role in the plant breeding of the future. Our summary and interpretation should prove useful to breeders as they assess the value of GS in the context of their populations and resources.
MGG Molecular & General Genetics, 1995
Restriction fragment length polymorphism (RFLP) markers were used to map male fertility restoring... more Restriction fragment length polymorphism (RFLP) markers were used to map male fertility restoring gene that was transferred from chromosome 6U of Aegilops umbellulata Zhuk. to wheat. Segments of chromosome 6U bearing the gene that restore fertility to T. timopheevi Zhuk. male sterile cytoplasm were identified in all four translocation lines by two probes, BCD21 and BCD342. Lines 040-5,061-1 and 061-4 are T6BL.6BS-6U translocations, while line 2114 is a T6AL.6AS-6U translocation. Line 2114 has a much larger 6U chromosomal segment and lower frequency of transmission of male gametes with the alien segment than the other three lines. The restoring gene carried by the 6U segment in 2114 showed high expres sivity and complete penetrance. This restoring gene is designated Rf6. A homoeologous chromosome recombination mechanism is discussed for the alien gene transfer.
Registration of ‘Corral’ Oat
Journal of Plant Registrations, 2012
... The pedigree of Corral is IL95-4774/ IL95-8346. The pedigree of IL95-4774 is 'Brawn&... more ... The pedigree of Corral is IL95-4774/ IL95-8346. The pedigree of IL95-4774 is 'Brawn' (PI 570656; Kolb et al., 1995)/IL90-5046. IL90-5046 was derived from the cross of two experimental breeding lines IL83-8037-1/ IL79-4924. The pedigree of IL83-8037-1 is 'Hazel' (PI 498424 ...
Molecular General Genetics Mgg, Dec 1, 1993
A set of cDNA clones, which had previously been mapped onto wheat chromosomes, was genetically ma... more A set of cDNA clones, which had previously been mapped onto wheat chromosomes, was genetically mapped onto the chromosomes of rice. The resulting comparative maps make it possible to estimate the degree of linkage conservation between these two species. A number of chromosomal rearrangements, some of which must have involved interchromosomal translocations, differentiate the rice and wheat genomes. However, synteny of a large proportion of the loci appears to be conserved between the two species. The results of this study, combined with those from a recently published comparative map of the rice and maize genomes, suggest that rice, wheat and maize share extensive homoeologies in a number of regions in their genomes. Some chromosomes (e.g. chromosome 4 in rice; chromosomes 2 and 2S in wheat and maize, respectively) may have escaped major rearrangement since the divergence of these species from their last common ancestor. Comparative maps for rice, wheat and maize should make it possible to begin uniting the genetics of these species and allow for transfer of mapping information (including centromere positions) and molecular marker resources (e.g. RFLP probes) between species. In addition, such maps should shed light on the nature of chromosome evolution that accompanied the radiation of grasses in the early stages of plant diversification.
To cite th is article / Pou r citer cet article -Moragues M., Royo C., Sorrells M.E. Gen etic rel... more To cite th is article / Pou r citer cet article -Moragues M., Royo C., Sorrells M.E. Gen etic relation sh ip an d stru ctu re of Mediterran ean du ru m wh eat.
Euphytica, 2002
A wheat microsatellite locus, Xgwm 261, whose 192-bp allele closely linked to the dwarfing gene R... more A wheat microsatellite locus, Xgwm 261, whose 192-bp allele closely linked to the dwarfing gene Rht8, on chromosome 2D, was used to screen 71 wheat cultivars from 13 countries to assess the variation at this locus. Screening of this wheat collection showed that a 165-bp allele and a 174-bp allele were the most frequent. None of the New Zealand cultivars possessed a 192-bp allele specific to Rht8, while only one cultivar from the US produced this important allele. The frequency of a 192-bp allele among these wheat cultivars was 5.63%. The highest allele frequency was observed for a 174-bp fragment (52.11%) followed by a 165-bp fragment (26.76%). The only durum wheat 'Cham 1', did not show any amplification due to the absence of D genome. Four new novel alleles, 180-bp, 198-bp, 200-bp and 204-bp present in the US and New Zealand wheat cultivars are reported.
Tag Theoretical and Applied Genetics Theoretische Und Angewandte Genetik, Aug 3, 2011
The recent emergence of wheat stem rust Ug99 and evolution of new races within the lineage threat... more The recent emergence of wheat stem rust Ug99 and evolution of new races within the lineage threatens global wheat production because they overcome widely deployed stem rust resistance (Sr) genes that had been eVective for many years. To identify loci conferring adult plant resistance to races of Ug99 in wheat, we employed an association mapping approach for 276 current spring wheat breeding lines from the International Maize and Wheat Improvement Center (CIMMYT). Breeding lines were genotyped with Diversity Array Technology (DArT) and microsatellite markers. Phenotypic data was collected on these lines for stem rust race Ug99 resistance at the adult plant stage in the stem rust resistance screening nursery in Njoro, Kenya in seasons 2008, 2009 and 2010. Fifteen marker loci were found to be signiWcantly associated with stem rust resistance. Several markers appeared to be linked to known Sr genes, while other signiWcant markers were located in chromosome regions where no Sr genes have been previously reported. Most of these new loci colocalized with QTLs identiWed recently in diVerent biparental populations. Using the same data and Q + K covariate matrices, we investigated the interactions among marker loci using linear regression models to calculate P values for pairwise marker interactions. Resistance marker loci including the Sr2 locus on 3BS and the wPt1859 locus on 7DL had signiWcant interaction eVects with other loci in the same chromosome arm and with markers on chromosome 6B. Other resistance marker loci had signiWcant pairwise interactions with markers on diVerent chromosomes. Based on these results, we propose that a complex network of gene-gene interactions is, in part, responsible for resistance to Ug99. Further investigation may provide insight for understanding mechanisms that contribute to this resistance gene network. Communicated by B. Keller.
Theoretical and Applied Genetics, Feb 1, 2007
Powdery mildew is a severe foliar disease for wheat and could cause great yield loss in epidemic ... more Powdery mildew is a severe foliar disease for wheat and could cause great yield loss in epidemic years. To explore new powdery mildew resistance genes, two einkorn accessions including TA2033 and M80, both resistant to this disease, were studied for the inheritance of resistance. Each accession possessed a single but different dominant resistance gene that was designated as Mlm2033 and Mlm80, respectively. Marker mapping indicated that they are both linked to Xgwm344 on the long arm of chromosome 7A. To establish their genetic relationship with Pm1 on 7AL, five RFLP markers previously reported to co-segregate with Pm1a were converted to STS markers. Three of them detected polymorphism between the mapping parents and were mapped close to Mlm2033 or Mlm80 or both. Xmag2185, the locus determined by the STS marker derived from PSR680, one of the RFLP markers, was placed less than 2 cM away from them. The allelism test indicated that Mlm2033 and Mlm80 are likely allelic to each other. In addition, through comparative and EST mapping, more markers linked to these two genes were identified. The high density mapping of Mlm2033 and Mlm80 will contribute to map-based cloning of the Pm1 locus. The markers for both genes will also facilitate their transfer to wheat. Communicated by F. Ordon.
Genetic progress through selection is directly related to the amount of 3 variability present in ... more Genetic progress through selection is directly related to the amount of 3 variability present in the population and the quality of genes contributed by 4 the parents. Molecular markers can be used for estimating genetic 5 relationship between potential parents. A statistical methodology using the 6 size of a (1-a)% confidence interval was developed to determine the 7 precision in the estimation of genetic distance between pairs of cultivars. 8 Precision of relationship estimates was affected by type of genetic index 9 used, number of cultivars, and amount of genetic diversity present in the 10 studied group. The size of the (1-a)% confidence interval decreased as the 11 number of RFLP fragments increased. Oat and wheat diversity studies 12 were used to illustrate the methodology.
Genomic Selection in Plant Breeding
Advan Agron, 2011
“Genomic selection,” the ability to select for even complex, quantitative traits based on marker ... more “Genomic selection,” the ability to select for even complex, quantitative traits based on marker data alone, has arisen from the conjunction of new high-throughput marker technologies and new statistical methods needed to analyze the data. This review surveys what is known about these technologies, with sections on population and quantitative genetic background, DNA marker development, statistical methods, reported accuracies of genomic selection (GS) predictions, prediction of nonadditive genetic effects, prediction in the presence of subpopulation structure, and impacts of GS on long-term gain. GS works by estimating the effects of many loci spread across the genome. Marker and observation numbers therefore need to scale with the genetic map length in Morgans and with the effective population size of the population under GS. For typical crops, the requirements range from at least 200 to at most 10,000 markers and observations. With that baseline, GS can greatly accelerate the breeding cycle while also using marker information to maintain genetic diversity and potentially prolong gain beyond what is possible with phenotypic selection. With the costs of marker technologies continuing to decline and the statistical methods becoming more routine, the results reviewed here suggest that GS will play a large role in the plant breeding of the future. Our summary and interpretation should prove useful to breeders as they assess the value of GS in the context of their populations and resources.
To introduce new genetic diversity into the bread wheat gene pool from its progenitor, Aegilops t... more To introduce new genetic diversity into the bread wheat gene pool from its progenitor, Aegilops tauschii (Coss.) Schmalh, 33 primary synthetic hexaploid wheat genotypes (SYN) were crossed to 20 spring bread wheat (BW) cultivars at the International Wheat and Maize Improvement Center. Modified single seed descent was used to develop 97 populations with 50 individuals per population using first back-cross, biparental, and three-way crosses. Individuals from each cross were selected for short stature, early heading, flowering and maturity, minimal lodging, and free threshing. Yield trials were conducted under irrigated, drought, and heat-stress conditions from 2011 to 2014 in Ciudad Obregon, Mexico. Genomic estimated breeding values (GEBVs) of parents and synthetic derived lines (SDLs) were estimated using a genomic best linear unbiased prediction (GBLUP) model with markers in each trial. In each environment, there were SDLs that had higher GEBVs than their recurrent BW parent for yield. The GEBVs of BW parents for yield ranged from -0.32 in heat to 1.40 in irrigated trials. The range of the SYN parent GEBVs for yield was from -2.69 in the irrigated to 0.26 in the heat trials and were mostly negative across environments. The contribution of the SYN parents to improved grain yield of the SDLs was highest under heat stress, with an average GEBV for the top 10% of the SDLs of 0.55 while the weighted average GEBV of their corresponding recurrent BW parents was 0.26. Using the pedigree-based model, the accuracy of genomic prediction for yield was 0.42, 0.43, and 0.49 in the drought, heat and irrigated trials, respectively, while for the marker-based model these values were 0.43, 0.44, and 0.55. The SYN parents introduced novel diversity into the wheat gene pool. Higher GEBVs of progenies were due to introgression and retention of some positive alleles from SYN parents.
TAG Theoretical and Applied Genetics, 2002
Genetic variation present in 64 durum wheat accessions was investigated by using three sources of... more Genetic variation present in 64 durum wheat accessions was investigated by using three sources of microsatellite (SSR) markers: EST-derived SSRs (EST-SSRs) and two sources of SSRs isolated from total genomic DNA. Out of 245 SSR primer pairs screened, 22 EST-SSRs and 20 genomic-derived SSRs were polymorphic and used for genotyping. The EST-SSR primers produced high quality markers, but had the lowest level of polymorphism (25%) compared to the other two sources of genomic SSR markers (53%). The 42 SSR markers detected 189 polymorphic alleles with an average number of 4.5 alleles per locus. The coefficient of similarity ranged from 0.28 to 0.70 and the estimates of similarity varied when different sources of SSR markers were used to genotype the accessions. This study showed that EST-derived SSR markers developed in bread wheat are polymorphic in durum wheat when assaying loci of the A and B genomes. A minumum of ten EST-SSRs generated a very low probability of identity (0.36×10 −12 ) indicating that these SSRs have a very high discriminatory power. EST-SSR markers directly sample variation in transcribed regions of the genome, which may enhance their value in marker-assisted selection, comparative genetic analysis and for exploiting wheat genetic resources by providing a more-direct estimate of functional diversity.
Genetic Resources and Crop Evolution, 2007
A comprehensive characterization of crop germplasm is critical to the optimal improvement of the ... more A comprehensive characterization of crop germplasm is critical to the optimal improvement of the quality and productivity of crops. Genetic relationships and variability were evaluated among 63 durum wheat landraces from the Mediterranean basin using amplified fragment length polymorphisms (AFLPs) and microsatellites markers. The genetic diversity indices found were comparable to those of other crop species, with average polymorphism information content (PIC) values of 0.24 and 0.70 for AFLP and microsatellites, respectively. The mean number of alleles observed for the microsatellites loci was 9.15. Non-metric multi-dimensional scaling clustered the accessions according to their geographical origin with the landraces from the South shore of the Mediterranean Sea closely related. The results support two dispersal patterns of durum wheat in the Mediterranean basin, one through its north side and a second one through its south side.
Drought limits cereal yields in several regions of the world and plant water status plays an impo... more Drought limits cereal yields in several regions of the world and plant water status plays an important role in tolerance to drought. To investigate and understand the genetic and physiological basis of drought tolerance in barley, differentially expressed sequence tags (dESTs) and candidate genes for the
Identification of milling and baking quality QTL in multiple soft wheat mapping populations
Theoretical and Applied Genetics, 2015
Two mapping approaches were use to identify and validate milling and baking quality QTL in soft w... more Two mapping approaches were use to identify and validate milling and baking quality QTL in soft wheat. Two LG were consistently found important for multiple traits and we recommend the use marker-assisted selection on specific markers reported here. Wheat-derived food products require a range of characteristics. Identification and understanding of the genetic components controlling end-use quality of wheat is important for crop improvement. We assessed the underlying genetics controlling specific milling and baking quality parameters of soft wheat including flour yield, softness equivalent, flour protein, sucrose, sodium carbonate, water absorption and lactic acid, solvent retention capacities in a diversity panel and five bi-parental mapping populations. The populations were genotyped with SSR and DArT markers, with markers specific for the 1BL.1RS translocation and sucrose synthase gene. Association analysis and composite interval mapping were performed to identify quantitative trait loci (QTL). High heritability was observed for each of the traits evaluated, trait correlations were consistent over populations, and transgressive segregants were common in all bi-parental populations. A total of 26 regions were identified as potential QTL in the diversity panel and 74 QTL were identified across all five bi-parental mapping populations. Collinearity of QTL from chromosomes 1B and 2B was observed across mapping populations and was consistent with results from the association analysis in the diversity panel. Multiple regression analysis showed the importance of the two 1B and 2B regions and marker-assisted selection for the favorable alleles at these regions should improve quality.
Euphytica, 2011
The Plant Genome Journal, 2011
Genomic selection (GS) uses genome-wide molecular marker data to predict the genetic value of sel... more Genomic selection (GS) uses genome-wide molecular marker data to predict the genetic value of selection candidates in breeding programs. In plant breeding, the ability to produce large numbers of progeny per cross allows GS to be conducted within each family. However, this approach requires phenotypes of lines from each cross before conducting GS. This will prolong the selection cycle and may result in lower gains per year than approaches that estimate marker-effects with multiple families from previous selection cycles. In this study, phenotypic selection (PS), conventional marker-assisted selection (MAS), and GS prediction accuracy were compared for 13 agronomic traits in a population of 374 winter wheat (Triticum aestivum L.) advanced-cycle breeding lines. A cross-validation approach that trained and validated prediction accuracy across years was used to evaluate effects of model selection, training population size, and marker density in the presence of genotype × environment interactions (G×E). The average prediction accuracies using GS were 28% greater than with MAS and were 95% as accurate as PS. For net merit, the average accuracy across six selection indices for GS was 14% greater than for PS. These results provide empirical evidence that multifamily GS could increase genetic gain per unit time and cost in plant breeding.
Advances in Agronomy, 2011
Genomic selection," the ability to select for even complex, quantitative traits based on marker d... more Genomic selection," the ability to select for even complex, quantitative traits based on marker data alone, has arisen from the conjunction of new highthroughput marker technologies and new statistical methods needed to analyze the data. This review surveys what is known about these technologies, with sections on population and quantitative genetic background, DNA marker development, statistical methods, reported accuracies of genomic selection (GS) predictions, prediction of nonadditive genetic effects, prediction in the presence of subpopulation structure, and impacts of GS on long-term gain. GS works by estimating the effects of many loci spread across the genome. Marker and observation numbers therefore need to scale with the genetic map length in Morgans and with the effective population size of the population under GS. For typical crops, the requirements range from at least 200 to at most 10,000 markers and observations. With that baseline, GS can greatly accelerate the breeding cycle while also using marker information to maintain genetic diversity and potentially prolong gain beyond what is possible with phenotypic selection. With the costs of marker technologies continuing to decline and the statistical methods becoming more routine, the results reviewed here suggest that GS will play a large role in the plant breeding of the future. Our summary and interpretation should prove useful to breeders as they assess the value of GS in the context of their populations and resources.
MGG Molecular & General Genetics, 1995
Restriction fragment length polymorphism (RFLP) markers were used to map male fertility restoring... more Restriction fragment length polymorphism (RFLP) markers were used to map male fertility restoring gene that was transferred from chromosome 6U of Aegilops umbellulata Zhuk. to wheat. Segments of chromosome 6U bearing the gene that restore fertility to T. timopheevi Zhuk. male sterile cytoplasm were identified in all four translocation lines by two probes, BCD21 and BCD342. Lines 040-5,061-1 and 061-4 are T6BL.6BS-6U translocations, while line 2114 is a T6AL.6AS-6U translocation. Line 2114 has a much larger 6U chromosomal segment and lower frequency of transmission of male gametes with the alien segment than the other three lines. The restoring gene carried by the 6U segment in 2114 showed high expres sivity and complete penetrance. This restoring gene is designated Rf6. A homoeologous chromosome recombination mechanism is discussed for the alien gene transfer.
Registration of ‘Corral’ Oat
Journal of Plant Registrations, 2012
... The pedigree of Corral is IL95-4774/ IL95-8346. The pedigree of IL95-4774 is 'Brawn&... more ... The pedigree of Corral is IL95-4774/ IL95-8346. The pedigree of IL95-4774 is 'Brawn' (PI 570656; Kolb et al., 1995)/IL90-5046. IL90-5046 was derived from the cross of two experimental breeding lines IL83-8037-1/ IL79-4924. The pedigree of IL83-8037-1 is 'Hazel' (PI 498424 ...
Molecular General Genetics Mgg, Dec 1, 1993
A set of cDNA clones, which had previously been mapped onto wheat chromosomes, was genetically ma... more A set of cDNA clones, which had previously been mapped onto wheat chromosomes, was genetically mapped onto the chromosomes of rice. The resulting comparative maps make it possible to estimate the degree of linkage conservation between these two species. A number of chromosomal rearrangements, some of which must have involved interchromosomal translocations, differentiate the rice and wheat genomes. However, synteny of a large proportion of the loci appears to be conserved between the two species. The results of this study, combined with those from a recently published comparative map of the rice and maize genomes, suggest that rice, wheat and maize share extensive homoeologies in a number of regions in their genomes. Some chromosomes (e.g. chromosome 4 in rice; chromosomes 2 and 2S in wheat and maize, respectively) may have escaped major rearrangement since the divergence of these species from their last common ancestor. Comparative maps for rice, wheat and maize should make it possible to begin uniting the genetics of these species and allow for transfer of mapping information (including centromere positions) and molecular marker resources (e.g. RFLP probes) between species. In addition, such maps should shed light on the nature of chromosome evolution that accompanied the radiation of grasses in the early stages of plant diversification.
To cite th is article / Pou r citer cet article -Moragues M., Royo C., Sorrells M.E. Gen etic rel... more To cite th is article / Pou r citer cet article -Moragues M., Royo C., Sorrells M.E. Gen etic relation sh ip an d stru ctu re of Mediterran ean du ru m wh eat.
Euphytica, 2002
A wheat microsatellite locus, Xgwm 261, whose 192-bp allele closely linked to the dwarfing gene R... more A wheat microsatellite locus, Xgwm 261, whose 192-bp allele closely linked to the dwarfing gene Rht8, on chromosome 2D, was used to screen 71 wheat cultivars from 13 countries to assess the variation at this locus. Screening of this wheat collection showed that a 165-bp allele and a 174-bp allele were the most frequent. None of the New Zealand cultivars possessed a 192-bp allele specific to Rht8, while only one cultivar from the US produced this important allele. The frequency of a 192-bp allele among these wheat cultivars was 5.63%. The highest allele frequency was observed for a 174-bp fragment (52.11%) followed by a 165-bp fragment (26.76%). The only durum wheat 'Cham 1', did not show any amplification due to the absence of D genome. Four new novel alleles, 180-bp, 198-bp, 200-bp and 204-bp present in the US and New Zealand wheat cultivars are reported.
Tag Theoretical and Applied Genetics Theoretische Und Angewandte Genetik, Aug 3, 2011
The recent emergence of wheat stem rust Ug99 and evolution of new races within the lineage threat... more The recent emergence of wheat stem rust Ug99 and evolution of new races within the lineage threatens global wheat production because they overcome widely deployed stem rust resistance (Sr) genes that had been eVective for many years. To identify loci conferring adult plant resistance to races of Ug99 in wheat, we employed an association mapping approach for 276 current spring wheat breeding lines from the International Maize and Wheat Improvement Center (CIMMYT). Breeding lines were genotyped with Diversity Array Technology (DArT) and microsatellite markers. Phenotypic data was collected on these lines for stem rust race Ug99 resistance at the adult plant stage in the stem rust resistance screening nursery in Njoro, Kenya in seasons 2008, 2009 and 2010. Fifteen marker loci were found to be signiWcantly associated with stem rust resistance. Several markers appeared to be linked to known Sr genes, while other signiWcant markers were located in chromosome regions where no Sr genes have been previously reported. Most of these new loci colocalized with QTLs identiWed recently in diVerent biparental populations. Using the same data and Q + K covariate matrices, we investigated the interactions among marker loci using linear regression models to calculate P values for pairwise marker interactions. Resistance marker loci including the Sr2 locus on 3BS and the wPt1859 locus on 7DL had signiWcant interaction eVects with other loci in the same chromosome arm and with markers on chromosome 6B. Other resistance marker loci had signiWcant pairwise interactions with markers on diVerent chromosomes. Based on these results, we propose that a complex network of gene-gene interactions is, in part, responsible for resistance to Ug99. Further investigation may provide insight for understanding mechanisms that contribute to this resistance gene network. Communicated by B. Keller.
Theoretical and Applied Genetics, Feb 1, 2007
Powdery mildew is a severe foliar disease for wheat and could cause great yield loss in epidemic ... more Powdery mildew is a severe foliar disease for wheat and could cause great yield loss in epidemic years. To explore new powdery mildew resistance genes, two einkorn accessions including TA2033 and M80, both resistant to this disease, were studied for the inheritance of resistance. Each accession possessed a single but different dominant resistance gene that was designated as Mlm2033 and Mlm80, respectively. Marker mapping indicated that they are both linked to Xgwm344 on the long arm of chromosome 7A. To establish their genetic relationship with Pm1 on 7AL, five RFLP markers previously reported to co-segregate with Pm1a were converted to STS markers. Three of them detected polymorphism between the mapping parents and were mapped close to Mlm2033 or Mlm80 or both. Xmag2185, the locus determined by the STS marker derived from PSR680, one of the RFLP markers, was placed less than 2 cM away from them. The allelism test indicated that Mlm2033 and Mlm80 are likely allelic to each other. In addition, through comparative and EST mapping, more markers linked to these two genes were identified. The high density mapping of Mlm2033 and Mlm80 will contribute to map-based cloning of the Pm1 locus. The markers for both genes will also facilitate their transfer to wheat. Communicated by F. Ordon.
Genetic progress through selection is directly related to the amount of 3 variability present in ... more Genetic progress through selection is directly related to the amount of 3 variability present in the population and the quality of genes contributed by 4 the parents. Molecular markers can be used for estimating genetic 5 relationship between potential parents. A statistical methodology using the 6 size of a (1-a)% confidence interval was developed to determine the 7 precision in the estimation of genetic distance between pairs of cultivars. 8 Precision of relationship estimates was affected by type of genetic index 9 used, number of cultivars, and amount of genetic diversity present in the 10 studied group. The size of the (1-a)% confidence interval decreased as the 11 number of RFLP fragments increased. Oat and wheat diversity studies 12 were used to illustrate the methodology.
Genomic Selection in Plant Breeding
Advan Agron, 2011
“Genomic selection,” the ability to select for even complex, quantitative traits based on marker ... more “Genomic selection,” the ability to select for even complex, quantitative traits based on marker data alone, has arisen from the conjunction of new high-throughput marker technologies and new statistical methods needed to analyze the data. This review surveys what is known about these technologies, with sections on population and quantitative genetic background, DNA marker development, statistical methods, reported accuracies of genomic selection (GS) predictions, prediction of nonadditive genetic effects, prediction in the presence of subpopulation structure, and impacts of GS on long-term gain. GS works by estimating the effects of many loci spread across the genome. Marker and observation numbers therefore need to scale with the genetic map length in Morgans and with the effective population size of the population under GS. For typical crops, the requirements range from at least 200 to at most 10,000 markers and observations. With that baseline, GS can greatly accelerate the breeding cycle while also using marker information to maintain genetic diversity and potentially prolong gain beyond what is possible with phenotypic selection. With the costs of marker technologies continuing to decline and the statistical methods becoming more routine, the results reviewed here suggest that GS will play a large role in the plant breeding of the future. Our summary and interpretation should prove useful to breeders as they assess the value of GS in the context of their populations and resources.