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Thinopyrum distichum (Thunb.) Á. Löve (2n = 4x = 28; J1dJ1dJ2dJ2d) inhabits harsh, dry saline coastal dunes. Its adaptive genes can be of value to cultivated cereals; therefore, single‐chromosome additions were previously developed in hexaploid triticale (×Triticosecale Wittm. ex A. Camus) and common wheat (Triticum aestivum L.); however, their homoeology to triticale and wheat chromosomes remained largely unknown. Here we used genotyping‐by‐sequencing (GBS) to supplement conventional markers and determine the synteny of the Th. distichum addition chromosomes. Twenty‐seven triticale lines with single Th. distichum addition chromosomes were analyzed. Genotyping‐by‐sequencing yielded 2.75 million unique sequences that included 134,506 Th. distichum‐specific tags absent in the wheat, durum wheat [Triticum turgidum L. subsp. Durum (Desf.) van Slageren], ×Triticosecale spp., and rye (Secale cereale L.) controls. The Th. distichum‐specific tags were then sorted into 125,262 informative, single‐pair tags (from one homoeologous group) and 9,244 uninformative, multi‐group tags associated with more than one homoeologous group. Presence–absence patterns produced by the single‐pair tags suggested the presence of 11 different Th. distichum addition chromosomes whose associated sequence tags were then aligned to the Th. elongatum (Host) D. R. Dewey and Chinese Spring (CS) genomic databases to reveal their homoeology. Five prominent translocations were detected among the 11 Th. distichum addition chromosomes and three chromosomes appeared to be extensively restructured. The extra chromosomes in 10 additions to common wheat represented five different Th. distichum chromosomes that were also represented in the triticale set. The 11 distinct Th. distichum addition chromosomes constitute a useful genetic resource for continued dissection of the Th. distichum genomes. [ABSTRACT FROM AUTHOR]

Leaf rust resistance gene Lr62 was transferred from Aegilops neglecta Req. ex Bertol. to chromosome 6A of common wheat (Triticum aestivum L.) in 2008. After homoeologous chromosome pairing induction, smaller translocations that retained Lr62 were derived from it. This study compared the original translocation and the four apparently shortest recombinants to determine which would be the best suited for breeding. The translocations were analyzed using chromosome 6A and 6B simple sequence repeat (SSR) markers and genomic in situ hybridization. Recombined translocations 133, 135, and 136 were found to occur at the 6AS telomere. In addition to the wheat Xdupw217aest SSR locus on chromosome arm 6BS, the three recombinants also expressed an Ae. neglecta--derived homoeolocus (Xdupw217negl) that could be used to detect the presence of the Ae. neglecta chromosomal segment. The Lr62-129 translocation was relocated to 6BS in an allosyndetic recombination event that replaced the Xdupw217aest locus with Xdupw217negl. Lr62-129 retained the least Ae. neglecta chromatin and is therefore recommended for use in wheat breeding. [ABSTRACT FROM AUTHOR]

In an attempt to transfer the Lr56/Yr38 resistance loci from Aegilops sharonensis to wheat, a 6A-6Ssh chromosome translocation was produced. It involves essentially the entire chromosome 6Ssh with a small terminal segment of 6 AL. Induced homoeologous recombination of the translocated chromosome with 6A produced numerous recombinants including three recombined chromosomes carrying Lr56 that could not be precisely mapped for lack of suitable markers. This study aimed to determine the chromosomal locations of the translocation breakpoints in these three recombinants using various DNA markers as well as physical and genetic mapping. The three recombinants Lr56-39, -157 and -175 carry small segments of Ae. sharonensis chromatin distally to the Xgpw4329 and IWA5416 loci near the 6 AS telomere. The Ae. sharonensis chromatin that remains in each line includes a homoeolocus of the wheat marker locus Xdupw217 (on 6 BS) and its characteristic amplification product can be used as a dominant marker for the presence of Lr56. Of the three recombined chromosomes, Lr56-157 retained the least alien chromatin and appears to be the best candidate for use in wheat breeding. [ABSTRACT FROM AUTHOR]

Pomegranate (Punica granatum L.) has been cultivated from ancient times for its economic, ornamental and medicinal properties globally. Here, we report the isolation and characterization of 12 polymorphic microsatellite markers from a repeat-enriched genomic library of Punica granatum L. The genetic diversity of these loci was assessed in 60 genotypes of Punica granatum L. All loci were variable: the number of polymorphic alleles per locus ranged from two to five (average 2.9). The observed and expected heterozygosities ranged from 0.15 to 0.87 and 0.29 to 0.65, respectively. The polymorphic information content ranged from 0.26 to 0.61 (average: 0.43). To the best of our knowledge, this is the first time that polymorphic microsatellite markers have been reported for P. granatum L. These new markers should allow studies of the population structure and genetic diversity of pomegranate to be performed in the future. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a heavy metal that has no known biological function and is toxic for many living organisms. The maximum level of Cd concentration allowed in the international market for wheat grain is 0.2 mg kg21. Because phenotyping for Cd uptake is expensive and time consuming, molecular markers associated with genes conferring low Cd uptake would expedite selection and lead to the development of durum cultivars with reduced Cd concentrations. Here, we identified single nucleotide polymorphisms (SNPs) associated with a novel low Cd uptake locus in the durum experimental line D041735, which has hexaploid common wheat in its pedigree. Genetic analysis revealed a single major QTL for Cd uptake on chromosome arm 5BL within a 0.3 cM interval flanked by SNP markers. Analysis of the intervening sequence revealed a gene with homology to an aluminum-induced protein as a candidate gene. Validation and allelism tests revealed that the low Cd uptake gene identified in this study is different from the closely linked Cdu1-B gene, which also resides on 5BL. This study therefore showed that the durum experimental line D041735 contains a novel low Cd uptake gene that was likely acquired from hexaploid wheat. [ABSTRACT FROM AUTHOR]

Assembly of the barley (Hordeum vulgare L.) genome is complicated by its large size (5.1 Gb) and proportion of repetitive elements (84%). This process is facilitated by high resolution maps for aligning bacterial artificial chromosome (BAC) contigs along chromosomes. Available genetic maps, however, do not provide accurate information on the physical position of a large portion of the genome located in recombination-poor regions. Radiation hybrid (RH) mapping is an alternative approach, which is based on radiation-induced deletions along the length of chromosomes. In this study, the first RH map for barley chromosome 3H was developed. In total, 373 in vivo RH lines were generated by irradiating wheat (Triticum aestivum L.)-barley chromosome 3H addition lines and crossing them to a normal wheat cultivar. Each RH informative line (containing deletions) had, on average, three deletions. The induced deletion size varied from 36.58 Kb to 576.00 Mb, with an average length of 52.42 Mb. This initial chromosome 3H radiation hybrid (3H-RH) map had a 9.53× higher resolution than an analogous genetic map, reaching a maximum of >262.40× resolution in regions around the centromere. The final RH map was 3066.1 cR in length, with a 0.76 Mb resolution. It was estimated that the map resolution can be improved to an average of 30.34 Kb by saturating the 3H-RH map with molecular markers. The generated RH panel enabled alignment of BAC and sequenced contigs as small as 1.50 Kb in size. The high resolution and the coverage of poor-recombination regions make RH maps an ideal resource for barley genome assembly, as well as other genetic studies., (© 2015 The Authors.)

A few EST-derived STS markers localized on Qfhs.ndsu-3BS, a major QTL for resistance to Fusarium head blight (FHB) in wheat, have been previously identified in the 'Sumai 3'/'Stoa' population. In this study, we used a 'Wangshuibai' (resistant) /'Seri82' (susceptible) derived population, linkage group, QTL, and quantitative gene expression analysis to assess the genetic background dependence and stability of the EST-derived STS markers for use in marker aided selection to improve FHB resistance in wheat. Based on our results, a QTL in the map interval of Xsts3B-138_1-Xgwm493 on chromosome 3BS was detected for FHB resistance, which accounted for up to 16% of the phenotypic variation. BLASTN analysis indicated that Xsts3B-138_1 sequence had significant similarity with the resistance gene analogue. Real-time quantitative PCR showed that the relative expression of Xsts3B-138_1 in 'Wangshuibai' at 96 h after inoculation was 2.6 times higher than 'Seri82'. Our results underlined that EST-derived STS3B-138 markers could be predominantly used in marker aided selection to improve FHB resistance in wheat.