Iron (Fe) is a micronutrient for living organisms, and maintenance of Fe homeostasis is required for normal physiological functions. In this study, we report the function of a plasma membrane localized transporter (Polyol transporter 8, TaPLT8) in wheat, which is regarded as a novel regulator for Fe transport. TaPLT8 is specifically expressed in wheat roots and is induced by environmental Fe. Knockout of TaPLT8 increased Fe accumulation in roots but resulted in decreased Fe levels in shoots and grain. The change was caused by an altered tolerance or increased susceptibility to excessive environmental Fe in the vicinity of wheat roots, and inhibited root growth. Overexpression of TaPLT8A improved Fe transport from roots to shoots and grains, and increased grain Fe levels by up to 14.46%. Compared to wild type (WT) plants, the levels of Citrate and Fe levels in xylem sap were significantly decreased in taplt8 mutants but significantly increased in TaPLT8 OE lines. Transcriptome analysis of taplt8 mutants indicated that TaPLT8 affected citrate levels by influencing glycolysis and the citrate cycle pathway in roots, thus impacting Fe translocation. The findings demonstrated that TaPLT8 mediates Fe distribution in wheat roots and shoots, contributing to greater understanding of the contribution of TaPLT8 to Fe accumulation in grains.

Grain number per spikelet (GNS) is a key determinant of grain yield in wheat. A recombinant inbred line population comprising 300 lines was developed from a cross between a high GNS variety H461 and Chinese Spring from which the reference genome assembly of bread wheat was obtained. Both parents and the recombinant inbred lines were genotyped using the wheat 55K single nucleotide polymorphism (SNP) array. A high-density genetic map containing 21,197 SNPs was obtained. These markers covered each of the 21 chromosomes with a total linkage distance of 3792.71 cM. Locations of these markers in this linkage map were highly consistent with their physical locations in the genome assembly of Chinese Spring. The two parents and the whole RIL population were assessed for GNS in two consecutive years at two different locations. Based on multi-environment phenotype data and best liner unbiased prediction values, three quantitative trait loci (QTL) for GNS were identified. One of them located on chromosomes 2B and the other two on 2D. Phenotypic variation explained by these loci varied from 3.07% to 26.57%. One of these QTL, QGns.sicau-2D-2, was identified in each of all trials conducted. Based on the best linear unbiased prediction values, this locus explained 19.59%–26.57% of phenotypic variation. A KASP (Kompetitive Allele-Specific PCR) marker closely linked with this locus was generated and used to validate the effects of this locus in three different genetic backgrounds. The identified QTL and the KASP marker developed for it will be highly valuable in fine-mapping the locus and in exploiting it for marker-assisted selection in wheat breeding programs.

Kernel weight (KW), together with kernel number per unit area, determines yield of cereal crops. Here, two barley recombinant inbred lines (RILs) populations with a shared parent were used to identify loci controlling KW. One is Baudin/AWCS276 (BA) for which a linkage map was available. Several large-effect QTL controlling KW were detected in this population. Another is Morex/AWCS276 (MA). A linkage map with 5273 makers formed 1454 clusters, was constructed by the genotyping by sequence (GBS) data of 201 RILs from this population. A single marker was selected to represent each of the clusters and the linkage map constructed with these markers covers a total length of 1022.4 cM with an average interval of approximately 0.7 cM between loci. Three of the large-effect loci controlling KW (located on 2HL, 6HL, and 7HL, respectively) identified from the BA population were also detected in the MA population under different environments. The locus on 6HL was detected in each of the experiments conducted for both populations thus was selected for developing near isogenic lines (NILs). Apart from KW, the two isolines for each pair of the putative NILs obtained showed no significant difference for any of the morphological characteristics assessed. The average difference in KW between the isolines for all the NILs obtained was about 15% based on assessments under both glasshouse and field conditions. Taken advantage that high quality genome assemblies for both Morex and AWCS276 are available, we identified candidate genes underlying two of the three loci based on an orthologous analysis. The NILs developed and the candidate genes identified in this study should facilitate the cloning and functional analysis of genes regulating KW in barley.

Aegilops tauschii Ais a wild relative of common wheat (Triticum aestivum) and acts as an important resource of elite genes including genes for resistance to biotic and abiotic stresses. To improve the cadmium (Cd) tolerance of wheat varieties using A. tauschii resources, we investigated the genetic variation of biomass-based Cd tolerance in 235 A. tauschii accessions treated with 0 (control) and 100 μmol L⁻¹ CdCl₂ (as Cd stress). Simultaneously, we performed a genomewide association study (GWAS) using a single-nucleotide polymorphism chip containing 7185 markers. Six markers were found to be significantly associated with Cd tolerance by a general linear model and a mixed linear model. These markers were close to several candidate/flanking genes associated with Cd tolerance according to results in public databases, including pdil5-1, Acc-1, DME-5A, TaAP2-D, TaAP2-B, Vrn-B1, and FtsH-like protein gene. The A. tauschii accessions were classified as high, moderate, and low Cd-tolerant according to a secondary index, the synthetic index (SI), in proportions of 9%, 57%, and 34%, respectively. By the average SI, accessions from Afghanistan, Turkey, Azerbaijan, and Iran showed relatively high Cd tolerance.