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Key message: Powdery mildew resistance gene MlWE74, originated from wild emmer wheat accession G-748-M, was mapped in an NBS-LRR gene cluster of chromosome 2BS. Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a globally devastating disease. Wild emmer wheat (Triticum turgidum var. dicoccoides) is a valuable genetic resource for improving disease resistance in common wheat. A powdery mildew resistance gene was transferred to hexaploid wheat line WE74 from wild emmer accession G-748-M. Genetic analysis revealed that the powdery mildew resistance in WE74 is controlled by a single dominant gene, herein temporarily designated MlWE74. Bulked segregant analysis (BSA) and molecular mapping delimited MlWE74 to the terminal region of chromosome 2BS flanking by markers WGGBD412 and WGGBH346 within a genetic interval of 0.25 cM and corresponding to 799.9 kb genomic region in the Zavitan reference sequence. Sequence annotation revealed two phosphoglycerate mutase-like genes, an alpha/beta-hydrolases gene, and five NBS-LRR disease resistance genes that could serve as candidates for map-based cloning of MlWE74. The geographical location analysis indicated that MlWE74 is mainly distributed in Rosh Pinna and Amirim regions, in the northern part of Israel, where environmental conditions are favorable to the occurrence of powdery mildew. Moreover, the co-segregated marker WGGBD425 is helpful in marker-assisted transfer of MlWE74 into elite cultivars. [ABSTRACT FROM AUTHOR]

The abovementioned results imply that the silent genetic loci like I Pm41b i are a valuable resource of genetic variation in the wheat genome and therefore could be potentially utilized to enrich the genetic diversity in wheat breeding. Keywords: Pm41; allelic variation; genetic diversity; transposon; gene silencing EN Pm41 allelic variation genetic diversity transposon gene silencing 2039 2041 3 11/01/22 20221101 NES 221101 Common wheat ( I Triticum aestivum i . [Extracted from the article]

Summary: Powdery mildew poses severe threats to wheat production. The most sustainable way to control this disease is through planting resistant cultivars.We report the map‐based cloning of the powdery mildew resistance allele Pm5e from a Chinese wheat landrace. We applied a two‐step bulked segregant RNA sequencing (BSR‐Seq) approach in developing tightly linked or co‐segregating markers to Pm5e. The first BSR‐Seq used phenotypically contrasting bulks of recombinant inbred lines (RILs) to identify Pm5e‐linked markers. The second BSR‐Seq utilized bulks of genetic recombinants screened from a fine‐mapping population to precisely quantify the associated genomic variation in the mapping interval, and identified the Pm5e candidate genes.The function of Pm5e was validated by transgenic assay, loss‐of‐function mutants and haplotype association analysis. Pm5e encodes a nucleotide‐binding domain leucine‐rich‐repeat‐containing (NLR) protein. A rare nonsynonymous single nucleotide variant (SNV) within the C‐terminal leucine rich repeat (LRR) domain is responsible for the gain of powdery mildew resistance function of Pm5e, an allele endemic to wheat landraces of Shaanxi province of China.Results from this study demonstrate the value of landraces in discovering useful genes for modern wheat breeding. The key SNV associated with powdery mildew resistance will be useful for marker‐assisted selection of Pm5e in wheat breeding programs. [ABSTRACT FROM AUTHOR]

Key message: A new spot blotch (Bipolaris sorokiniana) resistance gene Sb4 was mapped in a genomic interval of 1.34 Mb on wheat chromosome 4BL. Spot blotch, caused by Bipolaris sorokiniana, has emerged as a serious concern for cultivation of wheat in warmer and humid regions of the world, which results in substantial yield losses and descends with quality. In this study, we identified and mapped a spot blotch resistance gene, designated as Sb4, against B. sorokiniana in wheat. Bulked segregant RNA-Seq (BSR-Seq) analysis and single-nucleotide polymorphism mapping showed that Sb4 is located on the long arm of chromosome 4B. A genetic linkage map of Sb4 was constructed using an F4 mapping population developed from the cross between 'GY17' and 'Zhongyu1211,' and Sb4 was delimited in a 7.14-cM genetic region on 4BL between markers B6811 and B6901. Using the Chinese Spring reference sequences of chromosome arm 4BL, 13 new polymorphic markers were developed. Finally, Sb4 was mapped in a 1.19-cM genetic interval corresponding to a 1.34-Mb physical genomic region of Chinese Spring chromosome 4BL containing 21 predicted genes. This study provides a foundational step for further cloning of Sb4 using a map-based approach. [ABSTRACT FROM AUTHOR]

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is one of the most destructive diseases that pose a great threat to wheat production. Wheat landraces represent a rich source of powdery mildew resistance. Here, we report the map-based cloning of powdery mildew resistance gene Pm24 from Chinese wheat landrace Hulutou. It encodes a tandem kinase protein (TKP) with putative kinase-pseudokinase domains, designated WHEAT TANDEM KINASE 3 (WTK3). The resistance function of Pm24 was validated by transgenic assay, independent mutants, and allelic association analyses. Haplotype analysis revealed that a rare 6-bp natural deletion of lysine-glycine codons, endemic to wheat landraces of Shaanxi Province, China, in the kinase I domain (Kin I) of WTK3 is critical for the resistance function. Transgenic assay of WTK3 chimeric variants revealed that only the specific two amino acid deletion, rather than any of the single or more amino acid deletions, in the Kin I of WTK3 is responsible for gaining the resistance function of WTK3 against the Bgt fungus. Powdery mildew is a major threat to world wheat yields. Here the authors describe the map-based cloning of Pm24, a gain-of-function powdery mildew resistance allele that encodes a tandem kinase-pseudokinase protein with a deletion in a kinase domain that is endemic to certain wheat landraces. [ABSTRACT FROM AUTHOR]

Background: Grain weight is an important yield component. Selection of advanced lines with heavy grains show high grain sink potentials and strong sink activity, which is an increasingly important objective in wheat breeding programs. Rice OsGS3 has been identified as a major quantitative trait locus for both grain weight and grain size. However, allelic variation of GS3 has not been characterized previously in hexaploid wheat. Results: We cloned 2445, 2393, and 2409 bp sequences of the homologs TaGS3-4A, TaGS3-7A, and TaGS3-7D in wheat 'Changzhi 6406', a cultivar that shows high grain weight. The TaGS3 genes each contained five exons and four introns, and encoded a deduced protein of 170, 169, and 169 amino acids, respectively. Phylogenetic analysis of plant GS3 protein sequences revealed GS3 to be a monocotyledon-specific gene and the GS3 proteins were resolved into three classes. The length of the atypical Gγ domain and the cysteine-rich region was conserved within each class and not conserved between classes. A single-nucleotide polymorphism in the fifth exon (at position 1907) of TaGS3-7A leads to an amino acid change (ALA/THR) and showed different frequencies in two pools of Chinese wheat accessions representing extremes in grain weight. Association analysis indicated that the TaGS3-7A-A allele was associated with higher grain weight in the natural population. The TaGS3-7A-A allele was favoured in global modern wheat cultivars but the allelic frequency varied among different wheat-production regions of China, which indicated that this allele is of potential utility to improve wheat grain weight in certain wheat-production areas of China. Conclusions: The novel molecular information on wheat GS3 homologs and the KASP functional marker designed in this study may be useful in marker-assisted breeding for genetic improvement of wheat. [ABSTRACT FROM AUTHOR]

Bulked segregant CGT-Seq-facilitated map-based cloning of a powdery mildew resistance gene originating from wild emmer wheat (Triticum dicoccoides) In this study, we cloned the powdery mildew resistance allele I MlWE18 i ( I NLR SP WE18 sp i ) whose locus is not present in the wheat reference genomes using a combined BSA and CGT-seq strategies. Most of the cloned wheat disease resistance genes are NLRs that tend to be PAVs between the resistance and susceptible genotypes, especially the genes derived from wild relatives (Li I et al i ., 2020; Walkowiak I et al i ., 2020). Keywords: BSA; ChIP-Seq; NLR; PAV EN BSA ChIP-Seq NLR PAV 1288 1290 3 07/28/21 20210701 NES 210701 Powdery mildew, caused by I Blumeria graminis i f. sp. I tritici i ( I Bgt i ), is a widely occurring foliar disease of wheat worldwide. [Extracted from the article]

Key message: We isolated a novel allele associated with grain length and grain weight in wheat, TaGL3-5A-G. The TaGL3-5A-G allele frequency is low in wheat, so it has potential for breeding. Selection of large-grain wheat showing big grain sink potential and strong sink activity is becoming an important objective in breeding programs. Here, we cloned a wheat TaGL3-5A gene that was orthologous to rice GL3 and was phylogenetically clustered with both monocot PPKL1 and its expression pattern was similar to grain size change at early and middle stages of seed development. The isolated TaGL3-5A genomic sequence was 10,227 bp long and included 21 exons and 20 introns. Alignment of the TaGL3-5A sequences in Beinong 6 and Yanda 1817 showed a G/A substitution in the 11th exon (position 5946) that would lead to an amino acid change (Met/Ile). Subsequently, a KASP marker was designed based on this SNP. Genotyping of RILs showed that TaGL3-5A was located on the wheat 5AL chromosome and was colocated with a significant grain length QTL in three independent environments and mean value. Association analysis revealed that the TaGL3-5A-G allele was significantly correlated with longer grains and higher thousand-kernel weight. Haplotype association analysis indicated that TaGL3-5A-G could enhance grain traits in combination with TaGS5-3A and TaGW2-6B. The frequency of TaGL3-5A-G was higher in modern cultivars than in landraces but was still low in major Chinese wheat production areas. Additionally, the frequency of the TaGL3-5A-G allele in hexaploid wheat was slightly lower than in Triticum dicoccoides and much lower than in Triticum turgidum. Hence, T. dicoccoides and T. turgidum represent valuable resources for transferring the TaGL3-5A-G allele into common wheat, which should lead to longer grain length. [ABSTRACT FROM AUTHOR]

Photosynthesis of carbohydrates is the primary source of grain yield in wheat. Photosynthetic organs, especially flag leaves and awns play important roles in wheat growth and development. Genetic analysis of flag leaf posture, size and shape and presence/absence of awns was conducted using a set of 269 recombinant inbred lines (RILs) derived from Yanda1817 × Beinong6. Six agronomic traits comprising flag leaf angle (FLAN), flag leaf width (FLW), flag leaf length (FLL), the ratio of length/width of flag leaf (FLR), flag leaf area (FLA) and presence/absence of awns were evaluated in Shijiazhuang (2011, 2012 and 2013) and Beijing (2012). Using the available high-density single nucleotide polymorphism and simple sequence repeats (SSR) genetic linkage map, a total of 61 putative quantitative trait loci (QTL) for FLAN, FLW, FLL, FLR and FLA were detected on 16 of the 21 wheat chromosomes excluding 1D, 4B, 5D, 6A and 7A, with single QTL in different environments explaining 2.49-42.41 % of the phenotypic variation. Among the identified QTL, 17 were for FLAN, 11 for FLW, seven for FLL, 13 for FLR and 13 for FLA. Twenty-five (41 %) QTL were detected in at least two environments, while four QTL for FLW were detected in all environments. Thirty QTL were associated with higher number of flag leaf traits originated from Yanda1817 alleles, whereas the remaining 31 QTL were derived from Beinong6. In addition, pleiotropic effects were detected for QTL on chromosomes 2D, 3B, 4A, 4D, 5A, 5B, 6B, 6D and 7D that could serve as target regions for fine mapping and marker-assisted selection in wheat breeding programs. Genetic analysis revealed that the presence/absence of awns in the RIL population is controlled by the awn-inhibitor gene B1 linked to SSR marker Xgwm291 on the long arm of chromosome 5A. Our results also suggest that physiological traits FLL, FLW and FLA were significantly and positively correlated to spike length (SL), grain weight per spike and grain number per spike. FLR was significantly and positively related to SL but negatively related to grain width and grain thickness (GT). In addition, the awn trait was strongly and positively correlated to thousand grain weight, grain length and GT. [ABSTRACT FROM AUTHOR]