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Wheat (Triticum aestivum L.) is a primary staple cereal and significant source of mineral nutrients in human diets. Therefore, increasing concen - tration of the essential mineral, Zn, and decreas - ing concentration of the toxic mineral, Cd, could significantly improve human health. Because plant mechanisms for uptake and translocation of Cd and Zn are related, we assessed both Cd and Zn concentration to evaluate their indepen - dence in hard winter wheat germplasm. Grain Cd concentrations of some genotypes grown in Nebraska trials were above the Codex guidance level (0.2 mg kg -1 ), and highly repeatable dif - ferences in grain Cd were found between pairs of low and moderate-Cd commercial cultivars. Grain Cd concentration was predicted by Cd concentration in aboveground plant tissues at anthesis. However, grain Zn concentration was not predicted by Zn concentration in aboveg - round plant tissues. Genome-wide associa- tion scans using high-density single nucleotide polymorphism (SNp) markers identified Cd- associated SNps on 5AL in a region homoeolo - gous to the Cdu1 locus on 5BL in durum wheat (Triticum turgidum L. var. durum Desf.). Genetic regulation of grain cadmium concentration in bread wheat may be more complex than in durum wheat because epistatic interactions between SNp markers were identified, and SN p marker haplotypes were imperfect predictors of grain Cd phenotype. The SN p marker asso - ciations with Zn concentration were weak and inconsistent across trials, and Zn concentration was independent of 5AL markers. The inde - pendent genetic regulation of grain Cd and Zn concentrations indicates that breeding low Cd hard winter wheat genotypes without reducing Zn concentration has high potential for success.

High-density single nucleotide polymorphism (SNP) genotyping arrays are a powerful tool for studying genomic patterns of diversity, inferring ancestral relationships between individuals in populations and studying marker-trait associations in mapping experiments. We developed a genotyping array including about 90 000 gene-associated SNPs and used it to characterize genetic variation in allohexaploid and allotetraploid wheat populations. The array includes a significant fraction of common genome-wide distributed SNPs that are represented in populations of diverse geographical origin. We used density-based spatial clustering algorithms to enable high-throughput genotype calling in complex data sets obtained for polyploid wheat. We show that these model-free clustering algorithms provide accurate genotype calling in the presence of multiple clusters including clusters with low signal intensity resulting from significant sequence divergence at the target SNP site or gene deletions. Assays that detect low-intensity clusters can provide insight into the distribution of presence-absence variation (PAV) in wheat populations. A total of 46 977 SNPs from the wheat 90K array were genetically mapped using a combination of eight mapping populations. The developed array and cluster identification algorithms provide an opportunity to infer detailed haplotype structure in polyploid wheat and will serve as an invaluable resource for diversity studies and investigating the genetic basis of trait variation in wheat. © 2014 The Authors Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

The Arabidopsis ethylene-responsive element-binding factor (AtERF) family of transcription factors has approximately 120 members, all of which possess a highly conserved ERF domain. AtERF1, AtERF4, AtEBP and CBF1 are members from different phylogenetic subgroups within the family. Electrophoretic mobility shift assay analyses revealed that the ERF domains of these four proteins were capable of binding specifically to either GCC or dehydration-responsive element (DRE) motifs. In vitro and in vivo binding assays of the four AtERFs with the DRE motif showed that the recognition of the CG step was indispensable in all four of the specific binding reactions, implying that there may be a universal binding characteristic of various ERF domains binding to a given consensus (e.g. the DRE motif). In addition, the core DNA-binding motifs preferred by the four AtERFs were identified, and all of these motifs contained a conserved CG step core. Thus, conserved recognition of the CG step may be the foundation of the formation of the stable complex by the ERF domain with the DRE motif, which is probably determined by the highly conserved residues presented in the DNA contact surface among the whole AtERF family members. The different preferences at flanking bases of individual ERF domains, which appear to be attributed to the subfamily- or subgroup-specific residues, may be essential discrimination of the target binding motif from various similar sequences by divergent AtERF domains.