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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: By applying comparative genomics analyses, a high-density genetic linkage map narrowed the powdery mildew resistance gene Pm41 originating from wild emmer in a sub-centimorgan genetic interval. Abstract: Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici, results in large yield losses worldwide. A high-density genetic linkage map of the powdery mildew resistance gene Pm41, originating from wild emmer ( Triticum turgidum var. dicoccoides) and previously mapped to the distal region of chromosome 3BL bin 0.63-1.00, was constructed using an F recombinant inbred line population derived from a cross of durum wheat cultivar Langdon and wild emmer accession IW2. By applying comparative genomics analyses, 19 polymorphic sequence-tagged site markers were developed and integrated into the Pm41 genetic linkage map. Ultimately, Pm41 was mapped in a 0.6 cM genetic interval flanked by markers XWGGC1505 and XWGGC1507, which correspond to 11.7, 19.2, and 24.9 kb orthologous genomic regions in Brachypodium, rice, and sorghum, respectively. The XWGGC1506 marker co-segregated with Pm41 and could be served as a starting point for chromosome landing and map-based cloning as well as marker-assisted selection of Pm41. Detailed comparative genomics analysis of the markers flanking the Pm41 locus in wheat and the putative orthologous genes in Brachypodium, rice, and sorghum suggests that the gene order is highly conserved between rice and sorghum. However, intra-chromosome inversions and re-arrangements are evident in the wheat and Brachypodium genomic regions, and gene duplications are also present in the orthologous genomic regions of Pm41 in wheat, indicating that the Brachypodium gene model can provide more useful information for wheat marker development. [ABSTRACT FROM AUTHOR]

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, a fungal disease caused by Blumeria graminis f. sp. tritici (Bgt), has a serious impact on wheat production. Loss of resistance in cultivars prompts a continuing search for new sources of resistance.Wild emmer wheat (Triticum turgidum ssp. dicoccoides, WEW), the progenitor of both modern tetraploid and hexaploid wheats, harbors many powdery mildew resistance genes. We report here the positional cloning and functional characterization of Pm41, a powdery mildew resistance gene derived from WEW, which encodes a coiled‐coil, nucleotide‐binding site and leucine‐rich repeat protein (CNL). Mutagenesis and stable genetic transformation confirmed the function of Pm41 against Bgt infection in wheat.We demonstrated that Pm41 was present at a very low frequency (1.81%) only in southern WEW populations. It was absent in other WEW populations, domesticated emmer, durum, and common wheat, suggesting that the ancestral Pm41 was restricted to its place of origin and was not incorporated into domesticated wheat.Our findings emphasize the importance of conservation and exploitation of the primary WEW gene pool, as a valuable resource for discovery of resistance genes for improvement of modern wheat cultivars. [ABSTRACT FROM AUTHOR]

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 powdery mildew resistance gene MlHLT derived from a Chinese wheat landrace maps within a 3.6 centimorgan (cM) genetic interval spanning a 13.4 megabase (Mb) physical genomic region on chromosome 1DS. Abstract: Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici ( Bgt) is a devastating disease that can cause severe yield losses. Chinese wheat landrace Hulutou confers nearly immune resistance against prevailing Bgt isolate E09 in Beijing. Genetic analysis indicate that the powdery mildew resistance of Hulutou is controlled by a single dominant gene, provisionally designated MlHLT. Bulked segregant analysis(BSA) and simple sequence repeat (SSR) mapping showed that MlHLT is located on chromosome arm 1DS between markers Xgwm337 and Xcfd83/ Xcfd72. By applying comparative genomics analysis, collinearity genomic regions of the MlHLT locus on Aegilops tauschii chromosome 1DS were identified in Brachypodium distachyon chromosome 2, rice chromosome 5 and sorghum chromosome 9, respectively. Three new polymorphic markers were developed using the draft genome sequences and the extended single nucleotide polymorphism (SNP) marker sequences of Ae. tauschii accession AL8/78, as well as the Triticum aestivum cv. Chinese Spring 454 contig sequences and the International Wheat Genome Sequencing Consortium (IWGSC) survey sequences. MlHLT mapped into a 3.6 cM genetic interval spanning 13.4 Mb physical genomic region containing seven contigs (ctg220, ctg4623, ctg1063, ctg5929, ctg3163, ctg699 and ctg1065) on 1DS that has synteny with a 369.8 kb genomic region in Brachypodium, a 380.8 kb genomic region in rice and a 298.4 kb genomic region in sorghum. The genetic and physical maps of MlHLT provide framework for map-based cloning and marker-assisted selection (MAS) of the powdery mildew resistance gene MlHLT in Hulutou. [ABSTRACT FROM AUTHOR]