A novel compensating wheat-Dasypyrum villosuminterstitial translocation carrying an approximately 15-Mb alien segment harboring PmV was created and demonstrated normal inheritance powdery mildew resistance. The powdery mildew resistance gene PmV, derived from the diploid Dasypyrum villosum accession No.1026, was previously introgressed into common wheat via the T6V#4S·6DL translocation. However, severely reduced gamete transmission ratio limited its breeding utility. To address this limitation, a recombinant translocation line T6VS#4S-6V#2S·6AL with improved transmission ratio was previously created, then two smaller segmental translocations—Dv6T25 (T6VS-6AS·6AL, harboring 6VS 0–85 Mb) and Dv6T31 (T6AS-6VS·6AL, harboring 6VS 70–270 Mb), both carrying PmV—were generated using the ph1b induction system. In this study, homologous recombination within the overlapping region of Dv6T25 and Dv6T31 was utilized. A novel compensating interstitial translocation line Dv6-IT1 (T6AS-6VS-6AS·6AL) was identified, carrying an introgressed fragment of approximately 15 Mb, which exhibits normal meiotic transmission and confers no deleterious effects on plant height or spike number across different genetic backgrounds. The development of Dv6-IT1 provides a promising resistance source with minimal linkage drag for wheat powdery mildew breeding. This study not only addresses the long-standing transmission barrier associated with the original T6V#4S·6DL translocation but also significantly reduces linkage drag. Moreover, it establishes a model strategy for the precise introgression of wild species resistance genes into common wheat, paving the way for more efficient and sustainable wheat improvement against evolving pathogen threats.

ABSTRACT Chromosome number variation and structural reorganization are key drivers of plant evolution, yet their genomic basis remains unclear due to incomplete representation of repetitive regions in existing assemblies. The Linum genus exhibits exceptional karyotypic diversity ( n = 7–43), providing a powerful system to investigate chromosome evolution. Here, we generated near telomere-to-telomere (T2T) genome assemblies for four species, including cultivated flax ( L. usitatissimum cv. CDC Bethune; n = 15), its wild progenitor ( L. bienne ; n = 15), and two related species ( L. decumbens and L. grandiflorum ; n = 8). Together with published genomes of L. lewisii ( n = 9) and L. tenue ( n = 10), these enabled reconstruction of chromosome evolution across six lineages. Phylogenomic analyses revealed a shared ancestral whole-genome duplication (WGD) associated with the n = 9 karyotype, followed by lineage-specific WGDs and divergent diploidization. The transition from n = 8 to the derived n = 15 flax lineage not only occurred without chromosome length expansion, but also with genome size reduction, indicating extensive internal restructuring. Comparative analyses showed that this restructuring was associated with lineage-specific expansion of a single DNA transposon family ( TE_00003234 ; hAT ), which is highly enriched in expansive pericentromeric regions that are characterized by low gene density and nucleotide diversity, suppressed recombination, segregation distortion, and extensive synteny disruption, unlike the LTR retrotransposon-rich pericentromeres typical of most plant genomes. These findings support a model in which lineage-specific DNA transposon expansion is associated with remodeling of pericentromeric architecture and large-scale chromosome restructuring following polyploidization.

This study identified the fertility alteration characteristics and cytological mechanisms of the thermo-photo-sensitive genic male sterile (TPSGMS) wheat line K64S. The fertility-sensitive stage of K64S extends from pollen mother cell formation to the tetrad development stage, with critical fertility alteration thresholds of 14–14.5 °C for temperature and 9–9.5 h for daylength. Under low-temperature and short-day conditions, K64S exhibits complete male sterility, whereas it returns to fertility under high-temperature and long-day conditions. Cytological analysis shows that K64S undergoes normal meiosis and successfully forms normal uninucleate microspores. 4′,6-diamidino-2-phenylindole (DAPI) staining revealed the uninucleate microspores failed to form binucleate microspores, with abortion occurring during the late uninucleate stage. Transmission electron microscopy indicates the pollen abortion in sterile K64S arises primarily from premature tapetal degeneration (a form of programmed cell death, PCD), initiated at the pollen mother cell stage, which disrupts nutrient supply and leads to abnormal nuclear division during subsequent microspore development. These findings provide insights into the cytological mechanism of pollen abortion in TPSGMS wheat and may guide hybrid wheat breeding and application.

Ym1 is the most widely utilized gene for wheat yellow mosaic virus (WYMV) disease control in worldwide wheat breeding. Here, we successfully isolated the responsible gene for Ym1. It encodes a typical CC-NBS-LRR type R protein, which is specifically expressed in root and induced upon WYMV infection. Ym1-mediated WYMV resistance is likely achieved by blocking viral transmission from the root cortex into steles, thereby preventing systemic movement to aerial tissues. Ym1 CC domain is essential for triggering cell death. Ym1 specifically interacts with WYMV coat protein, and this interaction leads to nucleocytoplasmic redistribution, a process for transitioning Ym1 from an auto-inhibited to an activated state. The activation subsequently elicits hypersensitive responses and establishes WYMV resistance. Ym1 is likely introgressed from the sub-genome Xn or Xc of polyploid Aegilops species. The findings highlight an exogenous-introgressed and root-specifically expressed R gene that confers WYMV resistance by recognizing the viral component.

SHORT SUMMARY:This study cloned the wheat powdery mildew resistance gene Pm6 via map-based cloning, which encodes an NLR protein. Through GWAS, its cognate pathogen effector AvrPm6 was characterized, revealing a direct physical interaction that triggers resistance. The findings provide crucial insights into the molecular mechanism of wheat immunity against powdery mildew.

Lateral root (LR) formation is governed by a complex regulatory network that includes various internal factors such as transcription factors (TFs) and phytohormones, of which ethylene is a key repressor. However, the core TFs that regulate ethylene biosynthesis and LR development remain unknown. Here, we found that the WRKY TF SbWRKY50 was required for LR development in Sorghum bicolour L. Overexpression of SbWRKY50 in sorghum increased the number and length of LRs, whereas both decreased in the CRISPR/Cas9-edited SbWRKY50 mutant. SbWRKY50 positively regulated LR generation by directly repressing several 1-aminocyclopropane-1-carboxylate synthase (ACS) genes. In addition, SbWRKY50 directly interacted with SbBMI1A to facilitate the recruitment of the PRC1 complex and induced H2A ubiquitination (H2Aub) accumulation on SbACS genes, thereby promoting epigenetic silencing and LR formation. The positive role of SbWRKY50 in stay-green and LR formation improves the agronomic traits of sorghum, improving drought tolerance and potentially contributing to increased sorghum yield.

SUMMARYPolyploidy is a prominent driver of plant diversification, accompanied with dramatic chromosomal rearrangement and epigenetic changes that affect gene expression. How chromatin interactions within and between subgenomes adapt to ploidy transition remains poorly understood. We generate open chromatin interaction maps for natural hexaploid wheat (AABBDD), extracted tetraploid wheat (AABB), diploid wheat progenitor Aegilops tauschii (DD) and resynthesized hexaploid wheat (RHW, AABBDD). Thousands of intra‐ and interchromosomal loops are de novo established or disappeared in AB subgenomes after separation of D subgenome, in which 37–95% of novel loops are lost again in RHW after merger of D genome. Interestingly, more than half of novel loops are formed by cascade reactions that are triggered by disruption of chromatin interaction between AB and D subgenomes. The interaction repressed genes in RHW relative to DD are expression suppressed, resulting in more balanced expression of the three homoeologs in RHW. The interaction levels of cascade anchors are decreased step‐by‐step. Leading single nucleotide polymorphisms of yield‐ and plant architecture‐related quantitative trait locus are significantly enriched in cascade anchors. The expression of 116 genes interacted with these anchors are significantly correlated with the corresponding traits. Our findings reveal trans‐regulation of intrachromosomal loops by interchromosomal interactions during genome merger and separation in polyploid species.

The Huang-Huai-Hai wheat region (HHHR) is characterized by the largest cultivation area and yield among all the major wheat-producing regions in China. Over the past 70 years, significant advances in wheat breeding have been achieved in this region, resulting in high and stable yields as well as improved disease resistance. However, there is a notable deficiency in the systematic molecular-level analyses of wheat breeding advantages in HHHR. To bridge this gap, we used a Wheat 55K SNP array to evaluate 384 accessions from a core collection of wheat germplasms across China to systematically analyze the distribution patterns of beneficial haplotypes associated with traits related to yield and powdery mildew resistance specific to HHHR. Our findings indicate that varieties from HHHR demonstrate significantly superior performance in terms of yield-related traits and powdery mildew resistance compared to those from other wheat regions. Using genome-wide association studies (GWAS) analysis, we identified the QTNs associated with both grain yield and powdery mildew resistance. Importantly, beneficial haplotypes were found at significantly higher frequencies in the HHHR than in other wheat-growing regions. Based on these haplotypes, the MFP-a gene was identified as potentially regulating jasmonic acid synthesis while also playing a role in grain development and conferring powdery mildew resistance. Furthermore, identity by descent (IBD) analysis revealed specific conserved genomic segments that have become fixed through selective breeding practices in HHHR, which may serve as invaluable resources for the targeted enhancement of yield and disease resistance traits in other wheat-growing areas. Finally, using the Aimengniu breeding lineage as a case study, we elucidated the genetic basis underlying the key founder parental formations utilized in breeding programs. This study not only provides essential references and guidance for future molecular breeding initiatives in China but also has implications for enhancing wheat production worldwide.

A powdery mildew (Pm) resistance locus PmRc1 was identified and transferred from Roegneria ciliaris into wheat. Two compensative translocation lines carrying PmRc1 were developed. Powdery mildew (Pm), caused by the biotrophic fungal pathogen Blumeria graminis f.sp. tritici (Bgt), is a global destructive disease of bread wheat (Triticum aestivum L.). Identifying and utilizing new Pm resistance gene(s) is the most fundamental work for disease control. Roegneria ciliaris (2n = 4 x= 28, genome ScScYcYc) is a wild relative species of cultivated wheat. In this work, we evaluated wheat-R. ciliaris disomic chromosome addition lines for Pm resistance in multiple years. The introduction of R. ciliaris chromosome 1Sc into wheat enhanced resistance. The resistance locus on 1Sc was designated as PmRc1. To cytologically map PmRc1, we induced structural rearrangements using ion irradiation and increasing homoeologous chromosomal recombination. The identified 43 1Sc translocation or deletion lines were used to construct 1Sc cytological bin map by marker analysis using 111 molecular markers. Based on the Pm resistance of the characterized structural rearrangement lines, the PmRc1 locus was cytologically mapped to bin 1ScS-8 of 1Sc short arm, flanked by markers CMH93-2 and CMH114-1. Two compensatory chromosomal translocation lines (T1ScS · 1BL and T1ScS-1AS · 1AL) carrying PmRc1 were developed and assessed for their agronomic traits. Translocation chromosome T1ScS · 1BL had enhanced Pm resistance accompanied by negative effects on grain number and single plant yield. Translocation chromosome T1ScS-1AS · 1AL had enhanced Pm resistance and increased spikelet number per spike, without any obvious negative effect on other tested traits. Thus, T1ScS-1AS · 1AL is recommended preferentially used in wheat breeding for Pm resistance.

Wheat is the second largest food crop with a very good breeding system and pedigree record in China. Investigating the genomic footprints of wheat cultivars will unveil potential avenues for future breeding efforts1,2. Here we report chromosome-level genome assemblies of 17 wheat cultivars that chronicle the breeding history of China. Comparative genomic analysis uncovered a wealth of structural rearrangements, identifying 249,976 structural variations with 49.03% (122,567) longer than 5 kb. Cultivars developed in 1980s displayed significant accumulations of structural variations, a pattern linked to the extensive incorporation of European and American varieties into breeding programmes of that era. We further proved that structural variations in the centromere-proximal regions are associated with a reduction of crossover events. We showed that common wheat evolved from spring to winter types via mutations and duplications of the VRN-A1 gene as an adaptation strategy to a changing environment. We confirmed shifts in wheat cultivars linked to dietary preferences, migration and cultural integration in Northwest China. We identified large presence or absence variations of pSc200 tandem repeats on the 1RS terminal, suggesting its own rapid evolution in the wheat genome. The high-quality genome assemblies of 17 representatives developed and their good complementarity to the 10+ pan-genomes offer a robust platform for future genomics-assisted breeding in wheat. The pan-genome of 17 wheat cultivars grown in China is explored, providing insights into the breeding history of wheat in East Asia.

Polyploidization in plants often leads to increased cell size and grain size,which may be affected by the increased genome dosage and transcription abundance.The synthesized Triticum durum(AABB)-Hay-naldia villosa(VV)amphiploid(AABBVV)has significantly increased grain size,especially grain length,than the tetraploid and diploid parents.To investigate how polyploidization affects grain development at the transcriptional level,we perform transcriptome analysis using the immature seeds of T.durum,H.villosa,and the amphiploid.The dosage effect genes are contributed more by differentially expressed genes from genome V of H.villosa.The dosage effect genes overrepresent grain development-related genes.Inter-estingly,the vernalization gene TaVRN1 is among the positive dosage effect genes in the T.durum-H.villosa and T.turgidum-Ae.tauschii amphiploids.The expression levels of TaVRN1 homologs are positively correlated with the grain size and weight.The TaVRN1-B1 or TaVRN1-D1 mutation shows delayed florescence,decreased cell size,grain size,and grain yield.These data indicate that dosage effect genes could be one of the important explanations for increased grain size by regulating grain development.The identification and functional validation of dosage effect genes may facilitate the finding of valuable genes for improving wheat yield.

Wheat hybrids have been widely demonstrated to have remarkable heterosis or hybrid vigor in increasing yield potential and stability since the 1960s. Two-line hybrid wheat can achieve higher yields than local varieties, especially in marginal environments. However, the commercial application of hybrid wheat is hindered by higher seed costs, primarily due to lower yields in hybrid seed production. Stigma exsertion has been verified as a decisive factor in increasing rice’s hybrid seed yield, but more investigation is needed in hybrid wheat breeding and production. In this study, four thermo-photo-sensitive genic male sterile lines, including K41S, K64S, K66S, and K68S, with different stigma exsertion rates (SERs) were used to compare the differences in floral architecture relative to stigma exsertion over two growing seasons. The results revealed that the K41S and K64S exhibited a relatively higher SER at 21.87% and 22.81%, respectively. No exserted stigma was observed in K66S, and K68S had an SER of only 0.82%. This study found that the stigma length, glume width and the length–width ratio of the glume were significantly correlated with the SER, with correlation coefficients of 0.46, −0.46 and 0.60, respectively. Other stigma features such as the branch angle, stretch width and hairbrush length, as well as the glume length, also had a weakly positive correlation with SER (r = 0.09–0.27). For K41S and K64S, the SER was significantly affected by the differences in the stigma branch angle and stigma stretch width among florets. A cross-pollination survey showed that the out-crossing ability of florets with an exserted stigma was about three times as high as that of florets with a non-exserted stigma. As a result, the stigma-exserted florets that accounted for 21.87% and 22.81% of the total florets in K41S and K64S produced 46.80% and 48.53% of the total cross-pollinated seeds in both sterile lines. These findings suggest that a longer stigma combined with a slender glume appears to be the essential floral feature of stigma exsertion in sterile wheat lines. It is expected that breeding and utilizing sterile lines with a higher SER would be a promising solution to cost-effective hybrid wheat seed production.

Two recessive powdery mildew resistance loci pmAeCIae8_2DS and pmAeCIae8_7DS from Aegilops tauschii were mapped and two synthesized hexaploid wheat lines were developed by distant hybridization. Wheat powdery mildew (Pm), one of the worldwide destructive fungal diseases, causes significant yield loss up to 30

Inefficient nitrogen (N) utilization in agricultural production has led to many negative impacts such as excessive use of N fertilizers, redundant plant growth, greenhouse gases, long-lasting toxicity in ecosystem, and even effect on human health, indicating the importance to optimize N applications in cropping systems. Here, we present a multiseasonal study that focused on measuring phenotypic changes in wheat plants when they were responding to different N treatments under field conditions. Powered by drone-based aerial phenotyping and the AirMeasurer platform, we first quantified 6 N response-related traits as targets using plot-based morphological, spectral, and textural signals collected from 54 winter wheat varieties. Then, we developed dynamic phenotypic analysis using curve fitting to establish profile curves of the traits during the season, which enabled us to compute static phenotypes at key growth stages and dynamic phenotypes (i.e., phenotypic changes) during N response. After that, we combine 12 yield production and N-utilization indices manually measured to produce N efficiency comprehensive scores (NECS), based on which we classified the varieties into 4 N responsiveness (i.e., N-dependent yield increase) groups. The NECS ranking facilitated us to establish a tailored machine learning model for N responsiveness-related varietal classification just using N-response phenotypes with high accuracies. Finally, we employed the Wheat55K SNP Array to map single-nucleotide polymorphisms using N response-related static and dynamic phenotypes, helping us explore genetic components underlying N responsiveness in wheat. In summary, we believe that our work demonstrates valuable advances in N response-related plant research, which could have major implications for improving N sustainability in wheat breeding and production.

Wheat (Triticum aestivum) is among the most important staple crops for safeguarding the food security of the growing world population. To bridge the gap between genebank diversity and breeding programs, we developed an advanced backcross-nested association mapping plus inter-crossed population (AB-NAMIC) by crossing three popular wheat cultivars as recurrent founders to 20 germplasm lines from a mini core collection. Selective backcrossing combined with selection against undesirable traits and extensive crossing within and between sub-populations created new opportunities to detect unknown genes and increase the frequency of beneficial alleles in the AB-NAMIC population. We performed phenotyping of 590 AB-NAMIC lines and a natural panel of 476 cultivars for six consecutive growing seasons and genotyped these 1066 lines with a 660K SNP array. Genome-wide association studies of both panels for plant development and yield traits demonstrated improved power to detect rare alleles and loci with medium genetic effects in AB-NAMIC. Notably, genome-wide association studies in AB-NAMIC detected the candidate gene TaSWEET6-7B (TraesCS7B03G1216700), which has high homology to the rice SWEET6b gene and exerts strong effects on adaptation and yield traits. The commercial release of two derived AB-NAMIC lines attests to its direct applicability in wheat improvement. Valuable information on genome-wide association study mapping, candidate genes, and their haplotypes for breeding traits are available through WheatGAB. Our research provides an excellent framework for fast-tracking exploration and accumulation of beneficial alleles stored in genebanks.

SummaryFusarium head blight (FHB), caused by Fusarium graminearum, is a devastating disease in wheat (Triticum aestivum) that results in substantial yield losses and mycotoxin contamination. Reliable genetic resources for FHB resistance in wheat are lacking. In this study, we characterized glycoside hydrolase 12 (GH12) family proteins secreted by F. graminearum. We established that two GH12 proteins, Fg05851 and Fg11037, have functionally redundant roles in F. graminearum colonization of wheat. Furthermore, we determined that the GH12 proteins Fg05851 and Fg11037 are recognized by the leucine‐rich‐repeat receptor‐like protein RXEG1 in the dicot Nicotiana benthamiana. Heterologous expression of RXEG1 conferred wheat responsiveness to Fg05851 and Fg11037, enhanced wheat resistance to F. graminearum and reduced levels of the mycotoxin deoxynivalenol in wheat grains in an Fg05851/Fg11037‐dependent manner. In the RXEG1 transgenic lines, genes related to pattern‐triggered plant immunity, salicylic acid, jasmonic acid, and anti‐oxidative homeostasis signalling pathways were upregulated during F. graminearum infection. However, the expression of these genes was not significantly changed during infection by the deletion mutant ΔFg05851/Fg11037, suggesting that the recognition of Fg05851/Fg11037 by RXEG1 triggered plant resistance against FHB. Moreover, introducing RXEG1 into three other different wheat cultivars via crossing also conferred resistance to F. graminearum. Expression of RXEG1 did not have obvious deleterious effects on plant growth and development in wheat. Our study reveals that N. benthamiana RXEG1 remains effective when transferred into wheat, a monocot, which in turn suggests that engineering wheat with interfamily plant immune receptor transgenes is a viable strategy for increasing resistance to FHB.

Dasypyrum villosum is one of the most valuable gene resources in wheat improvement, especially for disease resistance. The mining of favorable genes from D. villosum is frustrated by the lack of a whole genome sequence. In this study, we generated a doubled-haploid line, 91C43DH, using microspore culture and obtained a 4.05-GB high-quality, chromosome-scale genome assembly for D. villosum. The assembly contains39 727 high-confidence genes, and 85.31% of the sequences are repetitive. Two reciprocal translocation events were detected, and 7VS-4VL is a unique translocation in D. villosum. The prolamin seed storage protein-coding genes were found to be duplicated; in particular, the genes encoding low-molecular-weight glutenin at the Glu-V3 locus were significantly expanded. RNA sequencing (RNA-seq) analysis indicated that, after Blumeria graminearum f.sp tritici (Bgt) inoculation, there were more upregulated genes involved in the pattern-triggered immunity and effector-triggered immunity defense pathways in D. villosum than in Triticum urartu. MNase hypersensitive sequencing (MH-seq) identified two Bgt-inducible MH sites (MHSs), one in the promoter and one in the 3' terminal region of the powdery mildew resistance (Pm) gene NLR1-V. Each site had two subpeaks and they were termed MHS1 (MHS1.1/1.2) and MHS2 (MHS2.1/2.2). Bgt-inducible MHS2.2 was uniquely present in D. villosum, and MHS1.1 was more inducible in D. villosum than in wheat, suggesting that MHSs may be critical for regulation of NLR1-V expression and plant defense. In summary, this study provides a valuable genome resource for functional genomics studies and wheat-D. villosum introgression breeding. The identified regulatory mechanisms may also be exploited to develop new strategies for enhancing Pm resistance by optimizing gene expression in wheat.

Twenty-two compensating wheat-Dasypyrum villosum translocations carrying the powdery mildew resistance gene PmV were developed using a triple marker selection strategy in a large homozygous ph1bph1b population. Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a destructive wheat disease in China. Currently, nearly all resistant varieties grown in the middle and lower reaches of the Yangtze River carry Pm21 which is present in a wheat-Dasypyrum villosum T6V#2S·6AL translocation. Its widespread use poses a strong risk of loss of effectiveness if the pathogen were to change. PmV, a Pm21 homolog carried by a wheat-D. villosum T6V#4S·6DL translocation, is also resistant to powdery mildew but is less transmittable and exploited in cultivars. To utilize PmV more effectively, a new recombinant translocation T6V#4S-6V#2S·6AL carrying PmV with a higher transmission rate was used as a basic material for inducing smaller alien translocations. A locally adapted ph1b-carrying line, Yangmai 23-ph1b, was crossed with T6V#4S-6V#2S·6AL to generate a homozygous ph1bph1b population of 6300 F3 individuals. A modified triple marker strategy based on three co-dominant markers including the functional marker MBH1 for PmV in combination with distal and proximal markers 6VS-GX4 and 6VS-GX17, respectively, was used to screen for new recombinants efficiently. Forty-eight compensating translocations were identified, 22 of which carried PmV. Two translocation lines, Dv6T25 with the shortest distal segment carrying PmV and Dv6T31 with the shortest proximal segment carrying PmV were identified, both expressed normal transmission and therefore could promote PmV in wheat breeding. This work exemplifies a model for rapid development of wheat-alien compensating translocations.

A new FHB resistance locus FhbRc1 was identified from the R. ciliaris chromosome 7Sc and transferred into common wheat by developing alien translocation lines. Fusarium head blight (FHB) caused by multiple Fusarium species is a globally destructive disease of common wheat. Exploring and utilization of resources with FHB resistance are the most effective and environmentally beneficial approach for the disease control. Roegneria ciliaris (Trin.) Nevski (2n = 4x = 28, ScScYcYc), a tetraploid wheat wild relative, possesses high resistance to FHB. In the previous study, a complete set of wheat-R. ciliaris disomic addition (DA) lines were evaluated for FHB resistance. DA7Sc had stable FHB resistance, which was confirmed to be derived from alien chromosome 7Sc. We tentatively designated the resistant locus as FhbRc1. For better utilization of the resistance in wheat breeding, we developed translocations by inducing chromosome structural aberrations using iron irradiation and the homologous pairing gene mutant ph1b. Totally, 26 plants having various 7Sc structural aberrations were identified. By marker analysis, a cytological map of 7Sc was constructed and 7Sc was dissected into 16 cytological bins. Seven alien chromosome aberration lines, which all had the bin 7Sc-1 on the long arm of 7Sc, showed enhanced FHB resistance. Thus, FhbRc1 was mapped to the distal region of 7ScL. A homozygous translocation line T4BS·4BL-7ScL (NAURC001) was developed. It showed improved FHB resistance, while had no obvious genetic linkage drag for the tested agronomic traits compared with the recurrent parent Alondra’s. When transferring the FhbRc1 into three different wheat cultivars, the derived progenies having the translocated chromosome 4BS·4BL-7ScL all showed improved FHB resistance. This revealed the potential value of the translocation line in wheat breeding for FHB resistance.

The QYm.nau-2D locus conferring wheat yellow mosaic virus resistance is an exotic introgression and we developed 11 diagnostic markers tightly linked to QYm.nau-2D. Wheat yellow mosaic virus (WYMV) is a serious disease of winter wheat in China. Breeding resistant varieties is the most effective strategy for WYMV control. A WYMV resistant locus QYm.nau-2D on the chromosome arm 2DL has been repeatedly reported but the mapped region is large. In the present study, we screened recombinants using a biparental population and mapped QYm.nau-2D into an 18.8 Mb physical interval. By genome-wide association studies of 372 wheat varieties for WYMV resistance in four environments, we narrowed down QYm.nau-2D into a 16.4 Mb interval. Haplotype analysis indicated QYm.nau-2D were present as six different states due to recombination during hybridization breeding. QYm.nau-2D was finally mapped into a linkage block of 11.2 Mb. Chromosome painting using 2D specific probes and collinearity analysis among the published sequences corresponding to QYm.nau-2D region indicated the block was an exotic introgression. The Illumina-sequenced reads of four diploid Aegilops species were mapped to the sequence of Fielder, a variety having the introgression. The mapping reads were significantly increased at the putative introgression regions of Fielder. Ae. uniaristata (NN) had the highest mapping reads, suggesting that QYm.nau-2D was possibly an introgression from genome N. We investigated the agronomic performances of different haplotypes and observed no linkage drag of the alien introgression for the 15 tested traits. For marker-assisted selection of QYm.nau-2D, we developed 11 diagnostic markers tightly linked to the locus. This research provided a case study of an exotic introgression, which has been utilized in wheat improvement for WYMV resistance.