Search

The leaf rust resistance locus Lr19, which was transferred to wheat (Triticum aestivum) from its relative Thinopyrum ponticum in 1966, still confers broad resistance to most known races of the leaf rust pathogen Puccinia triticina (Pt) worldwide. However, this gene has not previously been fine-mapped, and its tight linkage with a gene causing yellow pigmentation has limited its application in bread wheat breeding. In this study, we genetically mapped Lr19 using a bi-parental population from a cross of two wheat-Th. ponticum substitution lines, the Lr19-carrying line 7E1(7D) and the leaf rust-susceptible line 7E2(7D). Genetic analysis of the F2 population and the F2:3 families showed that Lr19 was a single dominant gene. Genetic markers allowed the gene to be mapped within a 0.3 cM interval on the long arm of Th. ponticum chromosome 7E1, flanked by markers XsdauK3734 and XsdauK2839. To reduce the size of the Th. ponticum chromosome segment carrying Lr19, the Chinese Spring Ph1b mutant was employed to promote recombination between the homoeologous chromosomes of the wheat chromosome 7D and the Th. ponticum chromosome 7E1. Two translocation lines with short Th. ponticum chromosome fragments carrying Lr19 were identified using the genetic markers closely linked to Lr19. Both translocation lines were resistant to 16 Pt races collected throughout China. Importantly, the linkage between Lr19 and yellow pigment content was broken in one of the lines. Thus, the Lr19 linked markers and translocation lines developed in this study are valuable resources in marker-assisted selection as part of common wheat breeding programs.

Eight environmentally stable QTL for grain yield-related traits were detected by four RIL populations, and two of them were validated by a natural wheat population containing 580 diverse varieties or lines. Yield and yield-related traits are important factors in wheat breeding. In this study, four RIL populations derived from the cross of one common parent Yanzhan 1 (a Chinese domesticated cultivar) and four donor parents including Hussar (a British domesticated cultivar) and three semi-wild wheat varieties in China were phenotyped for 11 yield-related traits in eight environments. An integrated genetic map containing 2009 single-nucleotide polymorphism (SNP) markers generated from a 90 K SNP array was constructed to conduct quantitative trait loci (QTL) analysis. A total of 161 QTL were identified, including ten QTL for grain yield per plant (GYP) and yield components, 49 QTL for spike-related traits, 43 QTL for flag leaf-related traits, 22 QTL for plant height (PH), and 37 QTL for heading date and flowering date. Eight environmentally stable QTL were validated in individual RIL population where the target QTL was notably detected, and six of them had a significant effect on GYP. Furthermore, Two QTL, QSPS-2A.4 and QSL-4A.1, were also validated in a natural wheat population containing 580 diverse varieties or lines, which provided valuable resources for further fine mapping and genetic improvement in yield in wheat.

Even frequently used in wheat breeding, we still have an insufficient understanding of the biology of the products

Background: Prolamins, unique to Gramineae (grasses), play a key role in the human diet. Thinopyrum elongatum (also known as tall wheatgrass, rush wheatgrass, or Eurasian quackgrass) of Elytrigia is genetically well-characterized, but little is known about its prolamin genes and the relationships with homologous loci in the Triticum genus.Results: In this study, a total of 19 α-gliadin, 9 γ-gliadin, 19 ω-gliadin, 2 high-molecular-weight glutenin subunit (HMW-GS), and 5 low-molecular-weight glutenin subunit (LMW-GS) genes in the Th. elongatum genome were annotated. The transcriptome data of Th. elongatum exhibited differential expression in quantity and pattern in the same subfamily or different subfamilies. In addition, microsynteny and phylogenetic analysis revealed dynamic changes of prolamin gene region and genetic affinities among Th. elongatum, T. aestivum, T. urartu, and Aegilops tauschii. The E genome, like the B genome, only contained DQ8-glia-α1/DQ8.5-glia-α1, which provided a theoretical basis for the study of celiac disease (CD). Dough rheological properties of T. aestivum-Th. elongatum disomic substitution (DS) lines 1E(1A), 1E(1D), and 3E(3A) showed much higher peak height values than that of their parent.Conclusions: Overall, this study provides a comprehensive overview of the prolamin gene superfamily in Th. elongatum, and suggests a promising use of this species in the generation of improved wheat breeds intended for the human diet.

Glutathione S-transferases (GSTs) are ancient proteins encoded by a large gene family in plants, which play multiple roles in plant growth and development. However, there has been little study on the GST genes of common wheat (Triticum aestivum) and its relatives (Triticum durum, Triticum urartu, and Aegilops tauschii), which are four important species of Triticeae. Here, a genome-wide comprehensive analysis of this gene family was performed on the genomes of common wheat and its relatives. A total of 346 GST genes in T. aestivum, 226 in T. durum, 104 in T. urartu, and 105 in Ae. tauschii were identified, and all members were divided into ten classes. Transcriptome analysis was used to identify GST genes that respond to salt stress in common wheat, which revealed that the reaction of GST genes is not sensitive to low and moderate salt concentrations but is sensitive to severe concentrations of the stressor, and the GST genes related to salt stress mainly come from the Tau and Phi classes. Six GST genes which respond to different salt concentrations were selected and validated by a qRT-PCR assay. These findings will not only provide helpful information about the function of GST genes in Triticeae species but also offer insights for the future application of salt stress resistance breeding in common wheat.

Fungal disease meets its matchFusariumhead blight (FHB), caused by a fungus, reduces wheat crop yield and introduces toxins into the harvest. From the assembly of the genome ofThinopyrum elongatum, a wild relative of wheat used in breeding programs to improve cultivated wheat, Wanget al.cloned a gene that can address both problems (see the Perspective by Wulff and Jones). The encoded glutathioneS-transferase detoxifies the trichothecene toxin and, when expressed in wheat, confers resistance to FHB.Science, this issue p.eaba5435; see also p.822

In plants, the mechanism for ecological sympatric speciation (SS) is little known. Here, after ruling out the possibility of secondary contact, we show that wild emmer wheat, at the microclimatically divergent microsite of “Evolution Canyon” (EC), Mt. Carmel, Israel, underwent triple SS. Initially, it split following a bottleneck of an ancestral population, and further diversified to three isolated populations driven by disruptive ecological selection. Remarkably, two postzygotically isolated populations (SFS1 and SFS2) sympatrically branched within an area less than 30 m at the tropical hot and dry savannoid south-facing slope (SFS). A series of homozygous chromosomal rearrangements in the SFS1 population caused hybrid sterility with the SFS2 population. We demonstrate that these two populations developed divergent adaptive mechanisms against severe abiotic stresses on the tropical SFS. The SFS2 population evolved very early flowering, while the SFS1 population alternatively evolved a direct tolerance to irradiance by improved ROS scavenging activity that potentially accounts for its evolutionary fate with unstable chromosome status. Moreover, a third prezygotically isolated sympatric population adapted on the abutting temperate, humid, cool, and forested north-facing slope (NFS), separated by 250 m from the SFS wild emmer wheat populations. The NFS population evolved multiple resistant loci to fungal diseases, including powdery mildew and stripe rust. Our study illustrates how plants sympatrically adapt and speciate under disruptive ecological selection of abiotic and biotic stresses.