Search

Bread wheat (Triticum aestivum) became a globally dominant crop after incorporating the D genome from the donor species Aegilops tauschii , but the evolutionary history that shaped the D genome during this process remains to be clarified. Here, we propose a renewed evolutionary model linking Ae. tauschii and the hexaploid wheat D genome by constructing an ancestral haplotype map covering 762 Ae. tauschii and hexaploid wheat accessions. We dissected the evolutionary trajectories of Ae. tauschii lineages and reported a few independent intermediate accessions, demonstrating that low-frequency inter-sublineage gene flow had enriched the diversity of Ae. tauschii. We discovered that the D genome of hexaploid wheat was inherited from a unified ancestral template, but with a mosaic composition that was highly mixed and derived mainly from three Ae. tauschii L2 sublineages located in the Caspian coastal region. This result suggests that early agricultural activities facilitated innovations in D-genome composition and finalized the success of hexaploidization. We found that the majority (51.4%) of genetic diversity was attributed to novel mutations absent in Ae. tauschii , and we identified large Ae. tauschii introgressions from various lineages, which expanded the diversity of the wheat D genome and introduced beneficial alleles. This work sheds light on the process of wheat hexaploidization and highlights the evolutionary significance of the multi-layered genetic diversity of the bread wheat D genome. By constructing a pan-ancestry haploblock map for the Triticum–Aegilops D genome covering 762 Aegilops tauschii and hexaploid wheat accessions, this study discovered that hexaploid wheat inherited a conserved ancestral genomic template across the D genome. Furthermore, the study elucidated its mosaic composition, which was mainly contributed by three Ae. tauschii L2 sublineages located in the Caspian coastal region. [ABSTRACT FROM AUTHOR]

SUMMARY: A series of polyploidizations in higher‐order polyploids is the main event affecting gene content in a genome. Each polyploidization event can lead to massive functional divergence because of the subsequent decrease in selection pressure on duplicated genes; however, the causal relationship between multiple rounds of polyploidization and the functional divergence of duplicated genes is poorly understood. We focused on the Triticum–Aegilops complex lineage and compared selection pressure before and after tetraploidization and hexaploidization events. Although both events led to decreased selection pressure on homoeologous gene pairs (compared with diploids and tetraploids), the initial tetraploidization had a greater impact on selection pressure on homoeologous gene pairs than did subsequent hexaploidization. Consistent with this, selection pressure on expression patterns for the initial event relaxed more than those for the subsequent event. Surprisingly, the decreased selection pressure on these homoeologous genes was independent of the existence of in‐paralogs within the same subgenome. Wheat homoeologous pairs had different evolutionary consequences compared with orthologs related to other mechanisms (ancient allopolyploidization, ancient autopolyploidization, and small‐scale duplication). Furthermore, tetraploidization and hexaploidization also seemed to have different evolutionary consequences. This suggests that homoeologous genes retain unique functions, including functions that are unlikely to be preserved in genes generated by the other duplication mechanisms. We found that their unique functions differed between tetraploidization and hexaploidization (e.g., reproductive and chromosome segregation processes). These findings imply that the substantial number of gene pairs resulting from multiple allopolyploidization events, especially initial tetraploidization, may have been a unique source of functional divergence. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a toxic heavy metal that accumulates in plants, negatively affecting their physiological processes, growth, and development, and poses a threat to human health through the food chain. 6-phosphogluconolactonase (PGL) is a key enzyme in the Oxidative Pentose Phosphate Pathway(OPPP) in plant cells, essential for cellular metabolism. The OPPP pathway provides energy and raw materials for organisms and is involved in antioxidant reactions, lipid metabolism, and DNA synthesis. This study describes the Cd responsive gene AetPGL from Aegilops tauschii. Overexpression of AetPGL under Cd stress increased main root length and germination rate in Arabidopsis. Transgenic lines showed higher antioxidant enzyme activities and lower malondialdehyde (MDA) content compared to the wild type. The transgenic Arabidopsis accumulated more Cd in the aboveground part but not in the underground part. Expression levels of AtHMA3, AtNRAMP5, and AtZIP1 in the roots of transgenic plants increased under Cd stress, suggesting AetPGL may enhance Cd transport from root to shoot. Transcriptome analysis revealed enrichment of differentially expressed genes (DEGs) in the plant hormone signal transduction pathway in AetPGL-overexpressing plants. Brassinosteroids (BR), Gibbenellin acid (GA), and Jasmonic acid (JA) contents significantly increased after Cd treatment. These results indicate that AetPGL may enhance Arabidopsis' tolerance to Cd by modulating plant hormone content. In conclusion, AetPGL plays a critical role in improving cadmium tolerance and accumulation and mitigating oxidative stress by regulating plant hormones, providing insights into the molecular mechanisms of plant Cd tolerance. [ABSTRACT FROM AUTHOR]

The present study demonstrated the differences in the seed metabolome and mycobiome of two Aegilops tauschii Coss accessions with different resistance to brown rust and powdery mildew. We hypothesized that the seeds of resistant accession k-1958 Ae. tauschii ssp. strangulata can contain a larger number of metabolites with antifungal activity compared with the seeds of susceptible Ae. tauschii ssp meyeri k-340, which will determine differences in the seed fungal community. Our study emphasizes the differences in the seed metabolome of the studied Ae. tauschii accessions. The resistant accession k-1958 had a higher content of glucose and organic acids, including pyruvic, salicylic and azelaic acid, as well as pipecolic acids, galactinol, glycerol and sitosterol. The seeds of Ae. tauschii-resistant accession k-1958 were found to contain more active substances with antifungal activity. The genera Cladosporium and Alternaria were dominant in the seed mycobiome of the resistant accession. The genera Alternaria, Blumeria and Cladosporium dominated in seed mycobiome of susceptible accession k-340. In the seed mycobiome of the resistant k-1958, a higher occurrence of saprotrophic micromycetes was found, and many of the micromycetes were biocontrol agents. It was concluded that differences in the seed metabolome of Ae. tauschii contributed to the determination of the differences in mycobiomes. [ABSTRACT FROM AUTHOR]

Abstract Heavy metal pollution causes severe abiotic stress in cereal crops around the world. This study investigated the effects of different concentrations (0, 100, 200, and 300 mg·kg–1) of nickel, lead, and copper stress on the growth and biochemical responses of Aegilops tauschii seedlings, to provide a reference for research on the mechanism of invasion and screening potential sources of wheat tolerance genes. The results showed that nickel, lead, and copper stress caused a significant decrease in the contents of chlorophyll a, chlorophyll b, and chlorophyll (a + b) in A. tauschii, thereby inhibiting photosynthesis to different degrees and hindering seedling growth, which was reflected in significant reductions in plant height and root length, with the most notable effect observed under stress by 300 mg·kg–1 lead. As the concentration of heavy metals increased, the activities of antioxidant enzymes (SOD, POD, and APX), non-enzymatic antioxidants (GSH and AsA), and the contents of osmotic regulatory substances (proline and soluble proteins) in A. tauschii significantly increased. Additionally, heavy metal stress increased H2O2 and TBARS levels. However, when the nickel, lead, and copper concentrations reached 300 mg·kg–1, no significant differences were found in H2O2 or TBARS levels compared to those in the CK group. To summarize, A. tauschii can mitigate the accumulation of ROS and membrane lipid peroxidation caused by heavy metal stress through self-regulation, thus exhibiting a certain degree of tolerance to stress caused by different concentrations of nickel, lead, and copper. Finally, the evaluation using the membership function method revealed that among the three heavy metals, A. tauschii exhibited the strongest adaptation to Cu, followed by Ni and Pb.

Grain hardness is an important end-use quality trait which can significantly affect milling and processing quality of wheat. It is controlled by Puroindoline (Pin) genes in wheat, of which Pina-D1 and Pinb-D1 control major phenotypic variation, while Pinb-B2 explain moderate variation. We analyzed the allelic variation of three Pin genes in a panel of 227 synthetic hexaploid wheats (SHWs) using allele-specific markers either previously available or newly developed in this study to identify new alleles and facilitate their introgression. Eight different alleles were identified in Pina-D1 gene using six newly developed markers. The wild-type alleles, Pina-D1a and Pinb-D1a, were identified in 11.6 and 24.2% of accessions, respectively. It was found that Pina-D1c was most frequent (30.7%), followed by Pina-D1e allele (18%) at Pina-D1. For Pinb-D1, three new markers were developed which classified synthetic wheats into four haplotype groups, of which Hap-IV (Pinb-D1j/Pinb-D1o) was most frequent (52.8%). A cleaved amplified polymorphic site (CAPS) marker using ApoI restriction enzyme successfully classified accessions into wild-type and non-wild-type groups. At Pinb-B2 gene, the frequency of Pinb-B2b allele was higher (76.2%) which is associated with relatively hard texture compared to Pinb-B2a allele. The results provide a deeper insight into the allelic composition of grain of grain texture genes in SHWs which can be introgressed to develop required texture market class using allele-specific markers developed in this study. [ABSTRACT FROM AUTHOR]

Aegilops tauschii Coss., an invasive weed, has a detrimental impact on the winter wheat cultivation areas of China. Understanding how drought influences competitive ability of A. tauschii can help identify traits related to its invasiveness and guide management. Slight, moderate, and severe soil drought stress conditions were established using potted weighing and water control methods. Concurrently, the de Wit replacement experiment was conducted to assess changes in morphological structure, biomass allocation, and physiological characteristics under varying intensities of soil drought stress. Based on observations of alterations in plant height, total leaf area, and total biomass, two-factor variance analysis revealed that soil drought inhibited the growth and development of both A. tauschii and Triticum aestivum L. ('Xinmai 32'). Furthermore, one-factor variance analysis revealed that A. tauschii and wheat responded to soil drought stress by increasing superoxide dismutase (SOD) activity and proline content. However, as drought severity escalated, chlorophyll content in A. tauschii and wheat declined significantly, while relative electrical conductivity (REC) and thiobarbituric acid (TBA) content increased markedly. The results of the fuzzy membership function indicated that A. tauschii exhibited greater drought tolerance compared to the tested wheat variety. Lastly, considering adjustments in the corrected index of relative competition intensity (CRCI), it was observed that soil drought amplified the competitive inhibition of A. tauschii on wheat. In short, A. tauschii was more tolerant of the soil drought stress than wheat through the favorable adjustment of morphology, biomass allocation pattern and physiological features, and soil drought intensified its competitive inhibition on wheat. [ABSTRACT FROM AUTHOR]

Background and Objectives: It is essential to identify the sources of seedling and adult plant resistance genes for gene pyramiding, genetic arrangement and introducing wheat cultivars with non-specific resistance or durable resistance. The complete homology of the D genome of Aegilops tauschii with the D genome of wheat, the clear botanical state, wide ecological compatibility, the presence of very high diversity in these traits and the ease of crossing with wheat have made Aegilops tauschii a very important source for gene transfer and wheat breeding. Until now, several genes of resistance to brown rust (leaf rust) were transferred from different species of Aegilops to high-yielding bread wheat cultivars whose resistance to brown rust was broken. Materials and Methods: In this research, 25 genotypes of Aegilops tauschii collected from its natural habitats from the Middle East, Central Asia (obtained from the Grain and Legume Seeds Collection of Ilam University) were used. This research was carried out in the Iraqi Agricultural Research Station in Gorgan, Iran in the cropping season of 2019-2019 in the form of a complete block design with three replications and under two disease stress and control conditions. In order to development and appearance of brown rust disease, the sensitive Bolani variety was cultivated around and between the crop rows. In addition, spore of the native races from Gorgan was sprayed over the studied genotypes under the stress condition. Inoculation with a ratio of one to five spores and Talc powder was applied at the two stages at sunset by dusting device. Results: The results showed that there was a significant difference among different genotypes of Aegilops tauschii in terms of susceptibility and resistance to brown rust disease and yeild component traits. Statistical analyzes showed a significant correlation between the characteristics of infection intensity, infection type, the area under the curve of disease progression, and various characteristics of yield components. The results of cluster analysis by Ward's method based on Euclidean distance and average algorithm for the resistance and yield component traits were placed the genotypes into four different groups including resistant, semi-resistant, semi-sensitive, and sensitive. Also, based on the results of combined analysis, a significant difference was observed for the yield components including kernel weight, number of kernel per plant, length of spike, number of kernel per spike and number of tillers under two conditions. Conclusion: Aegilops tauschii, having different genes for resistance to various diseases, is considered as a valuable parent and a rich gene source for transferring resistant genes to high-yielding cultivars. The results of this research showed that from the resistant and semi-resistant groups, suitable parents can be selected for crossbreeding with bread wheat in order to transfer the resistance gene to leaf rust. [ABSTRACT FROM AUTHOR]

SUMMARY: Pre‐harvest sprouting (PHS) is a significant threat to global food security due to its association with losses in both yield and quality. Among the genes involved in PHS resistance in wheat, PHS‐3D (TaMyb10‐D) plays a crucial role. Here, we characterized the sequence variations of TaMyb10 genes in 416 bread wheat and 302 Aegilops tauschii accessions. Within TaMyb10‐A sequences, we identified a deletion ranging from 214 to 305 bp in the signal and amino acid coding region, present in 61.3% of the accessions. Similarly, 79.3% of the TaMyb10‐B sequences within the third exon region exhibited a 19 bp deletion. Additionally, 40.8% of the accessions lacked the 2.4 Mb fragment (in/del mutations) on Chr3D, where TaMyb10‐D/PHS‐3D was located. Interestingly, the geographical distribution of accessions showed little correlation with the divergence of TaMyb10. TaMyb10‐A‐IIIDele, TaMyb10‐B‐IVDele, and TaMyb10‐D‐VDele genotypes were prevalent in wheat populations across continents. Despite their structural variations, the five distinct protein types exhibited comparable ability to bind the promoters of downstream genes in the flavonoid and ABA pathways, such as CHS, DFR, and NCED. Furthermore, the combination of TaMyb10 homologs was significantly associated with grain color and germination percentages. Accessions exclusively harboring TaMyb10‐D displayed red seed color and reduced germination percentages, indicating the predominant role of TaMyb10‐D compared to TaMyb10‐A and TaMyb10‐B. This comprehensive investigation enhances our understanding of the structural variations and functional divergence of TaMyb10, providing valuable insights and resources for improving PHS resistance in wheat. Significance Statement: TaPHS‐3D (TaMyb10‐D) plays a crucial role among the genes implicated in pre‐harvest sprouting resistance in wheat. Our study revealed a significant correlation between the combination of TaMyb10 homologs, grain color, and germination. Notably, TaMyb10‐D exhibited a more substantial functional impact than TaMyb10‐A and TaMyb10‐B. These findings deepen our understanding of the structural variations and functional distinctions within TaMyb10, providing valuable insights and resources for improving PHS resistance in wheat. [ABSTRACT FROM AUTHOR]

JASMONATE-ZIM DOMAIN (JAZ) repressor proteins work as co-receptors in the jasmonic acid (JA) signalling pathway and are essential for plant development and environmental adaptation. Despite wheat being one of the main staple food crops, until recently, comprehensive analysis of its JAZ gene family has been limited due to the lack of complete and high-quality reference genomes. Here, using the latest reference genome, we identified 17 JAZ genes in the wheat D-genome donor Aegilops tauschii. Then, 54 TaJAZs were identified in common wheat. A systematic examination of the gene structures, conserved protein domains, and phylogenetic relationships of this gene family was performed. Five new JAZ genes were identified as being derived from tandem duplication after wheat divergence from other species. We integrated RNA-seq data and yield QTL information and found that tandemly duplicated TaJAZ genes were prone to association with spike-related traits. Moreover, 12 TaJAZ genes were located within breeding selection sweeps, including 9 tandemly duplicated ones. Haplotype variation analysis of selected JAZ genes showed significant association of TaJAZ7A and TaJAZ13A with thousand-grain weight. Our work provides a clearer picture of wheat JAZ gene evolution and puts forward the possibility of using these genes for wheat yield improvement. [ABSTRACT FROM AUTHOR]

The interaction between plants and soil is an important aspect that affects the invasive ability of foreign plants and the invasiveness of ecosystems. The study on plant soil feedback of A. tauschii can provide reference for its invasion mechanism. Firstly, the effects of A. tauschii on the nutrients and enzyme activities of invaded soil were investigated; Secondly, in conjunction with soil sterilization, pot experiments were conducted using the De Wit substitution method to investigate the impact of different degree invasive soils on the development of A. tauschii and its interaction with wheat. The results showed that the invasion of A. tauschii significantly increased soil organic matter, soluble phosphorus and soluble potassium, while also causing a significant decrease in the concentration of nitrate nitrogen. And according to the changes of morphological and biomass indicators of A. tauschii, the results of two-way ANOVAs showed that the invaded soil and its microbiota have a positive feedback effect on the growth of A. tauschii. Finally, it can be seen from the value of the competition balance index, the competition ability of A. tauschii in different invasion degree soil is greater than that of wheat whether the soil invaded by A. tauschii had undergone sterilization treatment or not. In conclusion, the invasion potential of A. tauschii is not only derived from its strong competitiveness, but also may be related to the soil conditions. [ABSTRACT FROM AUTHOR]

Wheat powdery mildew is a fungal disorder caused by Blumeria graminis f. sp. tritici (Bgt) and is a severe and significant threat to the yield and quality of its host. The most practical and environmentally friendly approach to controlling this disease is through resistance gene identification to develop resistant varieties. Wild germplasm relatives of wheat are a valuable reservoir of genes contributing to resistance against powdery mildew. In our study, we identified the Aegilops tauschii germplasm "KU-2013", exhibiting seedling resistance to Bgt isolate E09 following hexaploidization. Genetic analysis and chromosomal localization of the powdery mildew resistance gene in doubled haploid (DH) KU-2013 indicated that the disease resistance gene in DHKU-2013 is governed by a dominant gene situated in 5DS, tentatively named PmKu-2013. Following the analysis of PmKu-2013 relative to the genes at the Pm2 locus, it was inferred that PmKu-2013 represented a distinct novel gene separate from Pm2. Using molecular marker analysis, PmKu-2013 was found to be ultimately mapped between the sdau5DS5-3 and sdau5DS6-1 markers, with genetic distances of 0.6 cM and 1.3 cM, respectively. Using markers tightly linked to PmKu-2013, the genotypes of core wheat varieties from various regions were identified, laying the foundation for the transfer and utilization of PmKu-2013 in molecular-assisted selection (MAS) for breeding. [ABSTRACT FROM AUTHOR]

Aegilops tauschii Coss. (2n = 2x = 14, DD) is a weed that competes with wheat for resources and performs better under various abiotic stresses. It is a valuable genetic material source for wheat crop improvement programs. In this study, greenhouse experiments were conducted to investigate the effects of drought levels on physio-biochemical parameters and expression profiling of the drought-resistant DREB gene. Under different drought levels, the physiological parameters such as plant height, dry weight, biomass, and leaf-related parameters exhibited variations. Moreover, photosynthetic parameters such as maximum and minimum fluorescence and photochemical and non-photochemical quenching were influenced by the different levels of drought stress, and their efficiency was noticed depending on the amount of water availability. Biochemical analysis revealed slight but significant changes in peroxidase, catalase, and proline content, while malondialdehyde exhibited higher variations under different drought stress conditions. In the analysis of DREB gene expression, eight populations of Ae. tauschii exhibited higher expression profiles than the control, i.e., no drought conditions. The expression profiles of Ae. tauschii showed a significant increase under drought conditions compared to the control, and the expression profiles of the DREB gene posed visible changes in correlation with observed variations in physio-biochemical activities. [ABSTRACT FROM AUTHOR]

In the face of climate change, bringing more useful alleles and genes from wild relatives of wheat is crucial to develop climate-resilient varieties. We used two populations of backcrossed recombinant inbred lines (BIL1 and BIL2), developed by crossing and backcrossing two intra-specifically diverse Aegilops tauschii accessions from lineage 1 and lineage 2, respectively, with the common wheat cultivar 'Norin 61′. This study aimed to identify quantitative trait loci (QTLs) associated with heat stress (HS) tolerance. The two BILs were evaluated under heat stress environments in Sudan for phenology, plant height (PH), grain yield (GY), biomass (BIO), harvest index (HI), and thousand-kernel weight (TKW). Grain yield was significantly correlated with BIO and TKW under HS; therefore, the stress tolerance index (STI) was calculated for these traits as well as for GY. A total of 16 heat-tolerant lines were identified based on GY and STI-GY. The QTL analysis performed using inclusive composite interval mapping identified a total of 40 QTLs in BIL1 and 153 QTLs in BIL2 across all environments. We detected 39 QTLs associated with GY-STI, BIO-STI, and TKW-STI in both populations (14 in BIL1 and 25 in BIL2). The QTLs associated with STI were detected on chromosomes 1A, 3A, 5A, 2B, 4B, and all the D-subgenomes. We found that QTLs were detected only under HS for GY on chromosome 5A, TKW on 3B and 5B, PH on 3B and 4B, and grain filling duration on 2B. The higher number of QTLs identified in BIL2 for heat stress tolerance suggests the importance of assessing the effects of intraspecific variation of Ae. tauschii in wheat breeding as it could modulate the heat stress responses/adaptation. Our study provides useful genetic resources for uncovering heat-tolerant QTLs for wheat improvement for heat stress environments. [ABSTRACT FROM AUTHOR]

Due to the low genetic diversity in the current wheat germplasm, gene mining from wild relatives is essential to develop new wheat cultivars that are more resilient to the changing climate. Aegilops tauschii, the D-genome donor of bread wheat, is a great gene source for wheat breeding; however, identifying suitable genes from Ae. tauschii is challenging due to the different morphology and the wide intra-specific variation within the species. In this study, we developed a platform for the systematic evaluation of Ae. tauschii traits in the background of the hexaploid wheat cultivar 'Norin 61' and thus for the identification of QTLs and genes. To validate our platform, we analyzed the seed dormancy trait that confers resistance to preharvest sprouting. We used a multiple synthetic derivative (MSD) population containing a genetic diversity of 43 Ae. tauschii accessions representing the full range of the species. Our results showed that only nine accessions in the population provided seed dormancy, and KU-2039 from Afghanistan had the highest level of seed dormancy. Therefore, 166 backcross inbred lines (BILs) were developed by crossing the synthetic wheat derived from KU-2039 with 'Norin 61' as the recurrent parent. The QTL mapping revealed one novel QTL, Qsd.alrc.5D, associated with dormancy explaining 41.7% of the phenotypic variation and other five unstable QTLs, two of which have already been reported. The Qsd.alrc.5D, identified for the first time within the natural variation of wheat, would be a valuable contribution to breeding after appropriate validation. The proposed platform that used the MSD population derived from the diverse Ae. tauschii gene pool and recombinant inbred lines proved to be a valuable platform for mining new and important QTLs or alleles, such as the novel seed dormancy QTL identified here. Likewise, such a platform harboring genetic diversity from wheat wild relatives could be a useful source for mining agronomically important traits, especially in the era of climate change and the narrow genetic diversity within the current wheat germplasm. [ABSTRACT FROM AUTHOR]

The phylogenetic positions of 39 Aegilops tauschii plants with different gliadin haplotypes and collected from two habitats in Dagestan, where the species is highly variable, were defined on an intraspecies phylogenetic tree based on DNA sequences of the nuclear gene Got2. Among Ae. tauschii subsp. tauschii plants, in addition to its single major phylogenetic lineage, a plant from a rare relict lineage previously noted very far from Dagestan in Iran, Turkmenistan and Pakistan, was found. Among Ae. tauschii subsp. strangulata plant representatives, two (out of five) major lineages of this subspecies and one relict lineage were found (all these were previously found in Dagestan). Knowing that Ae. tauschii has a high migration capacity, it was very surprising not to find plants representing the other three common major lineages of subsp. strangulata, two of which are known to inhabit Azerbaijan near Dagestan. Additionally, the locations of three Ae. tauschii accessions from the Yellow River Basin (two of which are known to be native to this region) were defined on the phylogenetic tree. They were found to belong to the major lineage of Ae. tauschii subsp. tauschii. The data obtained indicate that none of the several major lineages of subsp. strangulata, which successfully coexist, have ever been able to occupy the whole subspecies distribution area throughout the species evolutionary history. In contrast, in subsp. tauschii, each (or most) of several lineages that are now relicts, occupied the whole subsp. tauschii range for some period of time in the past. [ABSTRACT FROM AUTHOR]

To break the narrow diversity bottleneck of the wheat D genome, a set of Aegilops tauschii-wheat introgression (A-WI) lines was developed by crossing Ae. tauschii accession T015 with common wheat elite cultivar Zhoumai 18 (Zhou18). A high-density genetic map was constructed based on Single Nucleotide Polymorphism (SNP) markers and 15 yield-related traits were evaluated in 11 environments for detecting quantitative trait loci (QTL). A total of 27 environmentally stable QTL were identified in at least five environments, 20 of which were derived from Ae. tauschii T015, explaining up to 24.27% of the phenotypic variations. The major QTL for kernel length (KL), QKl-2D.5, was delimited to a physical interval of approximately 2.6 Mb harboring 52 candidate genes. Three Kompetitive Allele Specific PCR (KASP) markers were successfully developed based on nonsynonymous nucleotide mutations of candidate gene AetT093_2Dv1G100900.1 and showed that A-WI lines with the T015 haplotype had significantly longer KL than the Zhou18 haplotype across all 11 environments. Four primary valuable A-WIs with good trait performance and carrying yield-related QTL were selected for breeding improvement. The results will facilitate the efficient transfer of beneficial genes from Ae. tauschii into wheat cultivars to improve wheat yield and other traits.

The present study demonstrated the differences in the seed metabolome and mycobiome of two Aegilops tauschii Coss accessions with different resistance to brown rust and powdery mildew. We hypothesized that the seeds of resistant accession k-1958 Ae. tauschii ssp. strangulata can contain a larger number of metabolites with antifungal activity compared with the seeds of susceptible Ae. tauschii ssp meyeri k-340, which will determine differences in the seed fungal community. Our study emphasizes the differences in the seed metabolome of the studied Ae. tauschii accessions. The resistant accession k-1958 had a higher content of glucose and organic acids, including pyruvic, salicylic and azelaic acid, as well as pipecolic acids, galactinol, glycerol and sitosterol. The seeds of Ae. tauschii-resistant accession k-1958 were found to contain more active substances with antifungal activity. The genera Cladosporium and Alternaria were dominant in the seed mycobiome of the resistant accession. The genera Alternaria, Blumeria and Cladosporium dominated in seed mycobiome of susceptible accession k-340. In the seed mycobiome of the resistant k-1958, a higher occurrence of saprotrophic micromycetes was found, and many of the micromycetes were biocontrol agents. It was concluded that differences in the seed metabolome of Ae. tauschii contributed to the determination of the differences in mycobiomes.

Cadmium (Cd) is a toxic heavy metal that accumulates in plants, negatively affecting their physiological processes, growth, and development, and poses a threat to human health through the food chain. 6-phosphogluconolactonase (PGL) is a key enzyme in the Oxidative Pentose Phosphate Pathway(OPPP) in plant cells, essential for cellular metabolism. The OPPP pathway provides energy and raw materials for organisms and is involved in antioxidant reactions, lipid metabolism, and DNA synthesis. This study describes the Cd responsive gene AetPGL from Aegilops tauschii. Overexpression of AetPGL under Cd stress increased main root length and germination rate in Arabidopsis. Transgenic lines showed higher antioxidant enzyme activities and lower malondialdehyde (MDA) content compared to the wild type. The transgenic Arabidopsis accumulated more Cd in the aboveground part but not in the underground part. Expression levels of AtHMA3, AtNRAMP5, and AtZIP1 in the roots of transgenic plants increased under Cd stress, suggesting AetPGL may enhance Cd transport from root to shoot. Transcriptome analysis revealed enrichment of differentially expressed genes (DEGs) in the plant hormone signal transduction pathway in AetPGL-overexpressing plants. Brassinosteroids (BR), Gibbenellin acid (GA), and Jasmonic acid (JA) contents significantly increased after Cd treatment. These results indicate that AetPGL may enhance Arabidopsis’ tolerance to Cd by modulating plant hormone content. In conclusion, AetPGL plays a critical role in improving cadmium tolerance and accumulation and mitigating oxidative stress by regulating plant hormones, providing insights into the molecular mechanisms of plant Cd tolerance.

Aegilops tauschii is considered as an important gene source for improving common wheat, which has wide distribution and rich genetic variation. In order to understand genetic diverstity and population structure of A. tauschii from different origins, ISSR markers were used to evaluate genetic diversity and population structure of 56 A. tauschii accessions. The results were as follows：(1) The 170 polymorphic bands were detected by 16 ISSR primers, and polymorphic bands of each ISSR primer ranged from 3 to 18, with an average of 10.63. The variation of polymorphism information content（PIC）ranged from 0.17 to 0.85, with an averaged of 0.67. (2) The comparison among four populations indicated that the population genetic diversity of Central Asia was the highest (He=0.225 4, I=0.355 7) and gene flow between populations was relatively low (Nm=1.638 6). (3)The clustering results showed that 56 A. tauschii accessions were divided into two groups at the genetic similarity coefficient 0.67, of which eight accessions from Tajikistan and Turkmenistan were clustered in Group 2. And, the Group 1 including 48 accessions could be further divided into three sub-groups, which indicated that A. tauschii accessions with clustering together have the same origin. (4) Based on population structure analysis, 56 A. tauschii accessions were divided into five populations, of which the V population from Iran in West Asia had relatively consistent genetic background and relatively low degree of hybridization. Furthermore, the Q value analysis of populations showed that the genetic relationship of IV population were relatively complex, producing the most abundant genetic diversity. The results of this study can provide an important reference for analysis of genetic relationship, protection of biodiversity, and lay a foundation for the scientific utilization and evolution research of A. tauschii.

Abstract Background Weeds are not only economically important but also fascinating models for studying the adaptation of species in human-mediated environments. Aegilops tauschii is the D-genome donor species of common wheat but is also a weed that influences wheat production. How shading stress caused by adjacent wheat plants affects Ae. tauschii growth is a fundamental scientific question but is also important in agriculture, such as for weed control and wheat breeding. Result The present study indicated that shade avoidance is a strategy of Ae. tauschii in response to shading stress. Ae. tauschii plants exhibited growth increases in specific organs, such as stem and leaf elongation, to avoid shading. However, these changes were accompanied by sacrificing the growth of other parts of the plants, such as a reduction in tiller number. The two reverse phenotype responses seem to be formed by systemically regulating the expression of different genes. Fifty-six genes involved in the regulation of cell division and cell expansion were found to be downregulated, and one key upstream negative regulator (RPK2) of cell division was upregulated under shading stress. On the other hand, the upregulated genes under shading stress were mainly enriched in protein serine/threonine kinase activity and carbon metabolism, which are associated with cell enlargement, signal transduction and energy supply. The transcription factor WRKY72 may be important in regulating genes in response to shading stress, which can be used as a prior candidate gene for further study on the genetic regulation of shade avoidance. Conclusions This study sheds new light on the gene expression changes and molecular processes involved in the response and avoidance of Ae. tauschii to shading stress, which may aid more effective development of shading stress avoidance or cultivars in wheat and other crops in the future.

In the case of Aegilops tauschii the comparison of intraspecies molecular phylogeny based on DNA sequences of nuclear gene Got2 with electrophoretic polymorphism of allozymes and hystone H1 proteins is actually a comparison of the one detailed phylogenetic tree with a set of low resolution trees. It could help to understand peculiarities of the species evolutionary history and role of cross-pollination in it. Proteins polymorphism patterns rather satisfactory corresponded to Got2 DNA tree. Electrophoretic polymorphism of essentially polymorphic in Ae. tauschii subsp. strangulata protein encoding loci considered (Ak, Est2, Got1, Got3, Hst2, Hst3) and essentially polymorphic in Ae. tauschii subsp. tauschii locus Fdp displayed correspondence with the molecular phylogenetic tree: each allele was common or predominant on some branches of the tree and rare or absent on the other. In contrast, alleles of Cat2 locus, Cat235 and Cat2140, were “scattered” sporadically through Ae. tauschii subsp. tauschii branches on phylogenetic tree. Also in Ae. tauschii subsp. tauschii a set of different extremely rare allozyme alleles, Acph4113, Aco2110, Mdh1113, Nadhd188, was found among three out of four accessions belonging to one of the relict clades of this subspecies on the molecular phylogenetic tree. The data obtained displayed that subsp. tauschii, now being relatively less polymorphic than subsp. strangulata, in ancient times had good opportunities for genetic exchange between its different phylogenetic lineages, all but one of which are relicts in present time. And the patterns of Hst3977 allele occurrences indicated cross-pollination between subsp. tauschii and subsp. strangulata.

The duration of the vegetative period is an important agronomic characteristic of cereal crops. It is mainly influenced by the Vrn (response to vernalization) and Ppd (response to photoperiod) genes. In this work, we searched for alleles of several known genes of these two systems of response to external conditions in 15 accessions of Aegilops tauschii Coss. (syn. Ae. squarrosa L.), with the aim of studying the impact these alleles have on the vegetative period duration and growth habit. As a result, three allelic variants have been found for the Vrn-D1 gene: (i) one intact (winter type), (ii) one with a 5437 bp deletion in the first intron and (iii) one previously undescribed allele with a 3273 bp deletion in the first intron. It has been shown that the spring growth habit of Ae. tauschii can be developed due to the presence of a new allele of the Vrn-D1 gene. Significant differences in expression levels between the new allelic variant of the Vrn-D1 gene and the intact allele vrn-D1 were confirmed by qPCR. The new allele can be introgressed into common wheat to enhance the biodiversity of the spring growth habit and vegetative period duration of plants. [ABSTRACT FROM AUTHOR]

In this study, the molecular diversity among 95 accessions of Aegilops tauschii was investigated using a CAAT-box derived polymorphism (CBDP) marker system. Fifteen CBDP primers produced a total of 73 bands (4.87 bands per primer), of which 66 bands (91.9%) were polymorphic. The mean of polymorphic information content (PIC=0.26) and resolving power (Rp=5.62) indicated the capability of this marker system in evaluating genetic diversity in Ae. tauschii. In addition, the mean percentage of polymorphic loci, the number of observed alleles, effective alleles, the Shannon information index, and genetic diversity criterion were estimated to be 91.90%, 1.83, 1.47, 0.44, and 0.27, respectively. Analysis of molecular variance revealed that intra-population variation accounted for 96% of the total variance, while the remaining 4% was related to inter-population variation. Cluster analysis grouped the accessions into 7 main clusters. Also, according to principal coordinate analysis (PCoA), accessions were classified into six main groups, where the first two principal coordinates explained 24.19% of the total variation. The results of cluster analysis were relatively consistent with the results of PCoA. In this study, although the CBDP marker system did not completely separate Iranian accessions from other accessions however, accessions from Turkmenistan, Russia, Georgia, Turkey, Japan, and Kosovo were grouped in separate clades. Overall, the results showed that the CBDP marker system effectively identifies polymorphisms in the studied accessions. The results of this research suggest that the studied CBDP markers can be used in genetic fingerprinting and analysis of relationships between wheat and its related germplasm to evaluate various agronomic traits as well as tolerance to environmental stresses. [ABSTRACT FROM AUTHOR]

The spikelet number per spike (SNS) and spike length (SL) are key traits of interest for improving grain yields. Photoperiod-1 (Ppd-1) is a key regulator of inflorescence architecture and paired spikelet development in wheat. In this study, 170 recombinant inbred lines (RILs) derived by crossing synthetic hexaploid wheat (SHW-L1) with a commercial cultivar (Chuanmai 32) were evaluated for the number of days to heading (DTH), SNS and SL in four different years. Eight PPD1 combination homoeologs were also identified in the RILs by using genetic marker analysis. DTH had highly significant or significant positive correlations with SNS and SL, while SL also had a highly significant positive correlation with SNS. As a single factor, the photoperiod-sensitive ppd-D1b alleles had the largest effect on delaying heading, and these results showed that SL and SNS can eventually be increased. These findings confirmed that photoperiod-sensitive ppd-D1b is a potential means of increasing wheat yields. [ABSTRACT FROM AUTHOR]

JASMONATE-ZIM DOMAIN (JAZ) repressor proteins work as co-receptors in the jasmonic acid (JA) signalling pathway and are essential for plant development and environmental adaptation. Despite wheat being one of the main staple food crops, until recently, comprehensive analysis of its JAZ gene family has been limited due to the lack of complete and high-quality reference genomes. Here, using the latest reference genome, we identified 17 JAZ genes in the wheat D-genome donor Aegilops tauschii. Then, 54 TaJAZs were identified in common wheat. A systematic examination of the gene structures, conserved protein domains, and phylogenetic relationships of this gene family was performed. Five new JAZ genes were identified as being derived from tandem duplication after wheat divergence from other species. We integrated RNA-seq data and yield QTL information and found that tandemly duplicated TaJAZ genes were prone to association with spike-related traits. Moreover, 12 TaJAZ genes were located within breeding selection sweeps, including 9 tandemly duplicated ones. Haplotype variation analysis of selected JAZ genes showed significant association of TaJAZ7A and TaJAZ13A with thousand-grain weight. Our work provides a clearer picture of wheat JAZ gene evolution and puts forward the possibility of using these genes for wheat yield improvement.

Wheat powdery mildew is a fungal disorder caused by Blumeria graminis f. sp. tritici (Bgt) and is a severe and significant threat to the yield and quality of its host. The most practical and environmentally friendly approach to controlling this disease is through resistance gene identification to develop resistant varieties. Wild germplasm relatives of wheat are a valuable reservoir of genes contributing to resistance against powdery mildew. In our study, we identified the Aegilops tauschii germplasm “KU-2013”, exhibiting seedling resistance to Bgt isolate E09 following hexaploidization. Genetic analysis and chromosomal localization of the powdery mildew resistance gene in doubled haploid (DH) KU-2013 indicated that the disease resistance gene in DHKU-2013 is governed by a dominant gene situated in 5DS, tentatively named PmKu-2013. Following the analysis of PmKu-2013 relative to the genes at the Pm2 locus, it was inferred that PmKu-2013 represented a distinct novel gene separate from Pm2. Using molecular marker analysis, PmKu-2013 was found to be ultimately mapped between the sdau5DS5-3 and sdau5DS6-1 markers, with genetic distances of 0.6 cM and 1.3 cM, respectively. Using markers tightly linked to PmKu-2013, the genotypes of core wheat varieties from various regions were identified, laying the foundation for the transfer and utilization of PmKu-2013 in molecular-assisted selection (MAS) for breeding.

Due to the low genetic diversity in the current wheat germplasm, gene mining from wild relatives is essential to develop new wheat cultivars that are more resilient to the changing climate. Aegilops tauschii, the D-genome donor of bread wheat, is a great gene source for wheat breeding; however, identifying suitable genes from Ae. tauschii is challenging due to the different morphology and the wide intra-specific variation within the species. In this study, we developed a platform for the systematic evaluation of Ae. tauschii traits in the background of the hexaploid wheat cultivar ‘Norin 61’ and thus for the identification of QTLs and genes. To validate our platform, we analyzed the seed dormancy trait that confers resistance to preharvest sprouting. We used a multiple synthetic derivative (MSD) population containing a genetic diversity of 43 Ae. tauschii accessions representing the full range of the species. Our results showed that only nine accessions in the population provided seed dormancy, and KU-2039 from Afghanistan had the highest level of seed dormancy. Therefore, 166 backcross inbred lines (BILs) were developed by crossing the synthetic wheat derived from KU-2039 with ‘Norin 61’ as the recurrent parent. The QTL mapping revealed one novel QTL, Qsd.alrc.5D, associated with dormancy explaining 41.7% of the phenotypic variation and other five unstable QTLs, two of which have already been reported. The Qsd.alrc.5D, identified for the first time within the natural variation of wheat, would be a valuable contribution to breeding after appropriate validation. The proposed platform that used the MSD population derived from the diverse Ae. tauschii gene pool and recombinant inbred lines proved to be a valuable platform for mining new and important QTLs or alleles, such as the novel seed dormancy QTL identified here. Likewise, such a platform harboring genetic diversity from wheat wild relatives could be a useful source for mining agronomically important traits, especially in the era of climate change and the narrow genetic diversity within the current wheat germplasm.

Lodging is one of the most important factors affecting the high and stable yield of wheat worldwide. Solid-stemmed wheat has higher stem strength and lodging resistance than hollow-stemmed wheat does. There are many solid-stemmed varieties, landraces, and old varieties of durum wheat. However, the transfer of solid stem genes from durum wheat is suppressed by a suppressor gene located on chromosome 3D in common wheat, and only hollow-stemmed lines have been created. However, synthetic hexaploid wheat can serve as a bridge for transferring solid stem genes from tetraploid wheat to common wheat. In this study, the F1, F2, and F2:3 generations of a cross between solid-stemmed Syn-SAU-119 and semisolid-stemmed Syn-SAU-117 were developed. A single dominant gene, which was tentatively designated Su-TdDof and suppresses stem solidity, was identified in synthetic hexaploid wheat Syn-SAU-117 by using genetic analysis. By using bulked segregant RNA-seq (BSR-seq) analysis, Su-TdDof was mapped to chromosome 7DS and flanked by markers KASP-669 and KASP-1055 within a 4.53 cM genetic interval corresponding to 3.86 Mb and 2.29 Mb physical regions in the Chinese Spring (IWGSC RefSeq v1.1) and Ae. tauschii (AL8/78 v4.0) genomes, respectively, in which three genes related to solid stem development were annotated. Su-TdDof differed from a previously reported solid stem suppressor gene based on its origin and position. Su-TdDof would provide a valuable example for research on the suppression phenomenon. The flanking markers developed in this study might be useful for screening Ae. tauschii accessions with no suppressor gene (Su-TdDof) to develop more synthetic hexaploid wheat lines for the breeding of lodging resistance in wheat and further cloning the suppressor gene Su-TdDof. [ABSTRACT FROM AUTHOR]

Polyploidization plays important roles in the evolution and breeding of the common wheat. Aegilops tauschii, the D-genome progenitor of the common wheat, provides a valuable pool of resistance genes to multiple diseases. Extensive studies focus on the exploration of these genes for wheat improvement. However, few studies have unveiled alternations on genome-wide expression pattern and histone modifications induced by whole-genome doubling (WGD) process. In this study, we conducted transcriptome analysis for the diploid and tetraploid Ae. taushcii lines using the leaf and root tissues. Both lines tend to display similar tissue-specific pattern. Interestingly, we found that TEs located in genic regions were depleted of the repressive histone mark H3K27me3, whereas their adjacent chromatin was enriched with H3K27me3. The tetraploid line exhibited higher levels of H3K27me3 in those regions than the diploid line, particularly for genic regions associated with TEs of the long interspersed nuclear elements (LINEs), CACTA, PIF/Harbinger, Tc1/Mariner and unclassed DNA transposon. Surprisingly, the expression levels of these TEs cognate genes were negatively associated with the levels of H3K27me3 between the tetraploid and diploid lines, suggesting the five types of TEs located within genic regions might be involved in the regulation of the ploidy-related gene expression, possibly through differential enrichment of H3K27me3 in the genic regions. These findings will help to understand the potential role of specific types of TEs on transcription in response to WGD. [ABSTRACT FROM AUTHOR]

N6-methyladenosine modifications (m6A) is one of the most abundant and prevalent post-transcriptional RNA modifications in plants, playing the crucial role in plant growth and development and stress adaptation. However, the m6A regulatory machinery in Aegilops_tauschii, the D genome progenitor of common wheat, is not well understood at present. Here, we systematically identified the m6A-related genes in Aegilops with a genome-wide search approach. In total, 25 putative m6A genes composed of 5 writers, 13 readers and 7 erasers were obtained. A phylogenetic analysis clearly grouped them into three subfamilies with the same subfamily showing similar gene structures and conserved domains. These m6A genes were found to contain a large number of cis-acting elements associating with plant hormones, regulation of growth and development as well as stress response, suggesting their widespread regulation function. Furthermore, the expression profiling of them was investigated using RNA-seq data to obtain stress-responsive candidates, of which 5 were further validated with a qPCR analysis. Finally, the genetic variation of m6A-related genes was investigated between Aegilops and D subgenome of wheat based on re-sequencing data, and an obvious genetic bottleneck occurred on them during the wheat domestication process. The promising haplotype association with domestication and agronomic traits was also detected. This study provided some insights on the genomic organization and evolutionary features of m6A-related genes in Aegilops, which will facilitate the further functional study and also contribute to broaden the genetic basis for genetic improvement in wheat and other crops. [ABSTRACT FROM AUTHOR]

Aegilops tauschii is considered as an important gene source for improving common wheat, which has wide distribution and rich genetic variation. In order to understand genetic diverstity and population structure of A. tauschii from different origins, ISSR markers were used to evaluate genetic diversity and population structure of 56 A. tauschii accessions. The results were as follows: (1) The 170 polymorphic bands were detected by 16 ISSR primers, and polymorphic bands of each ISSR primer ranged from 3 to 18, with an average of 10.63. The variation of polymorphism information content (PIC) ranged from 0.17 to 0.85, with an averaged of 0.67. (2) The comparison among four populations indicated that the population genetic diversity of Central Asia was the highest (He=0.225 4, I=0.355 7) and gene flow between populations was relatively low (Nm=1.638 6) . (3) The clustering results showed that 56 A. tauschii accessions were divided into two groups at the genetic similarity coefficient 0.67, of which eight accessions from Tajikistan and Turkmenistan were clustered in Group 2. And, the Group 1 including 48 accessions could be further divided into three sub-groups, which indicated that A. tauschii accessions with clustering together have the same origin. (4) Based on population structure analysis, 56 A. tauschii accessions were divided into five populations, of which the V population from Iran in West Asia had relatively consistent genetic background and relatively low degree of hybridization. Furthermore, the Q value analysis of populations showed that the genetic relationship of IV population were relatively complex, producing the most abundant genetic diversity. The results of this study can provide an important reference for analysis of genetic relationship, protection of biodiversity, and lay a foundation for the scientific utilization and evolution research of A. tauschii. [ABSTRACT FROM AUTHOR]

Background: Weeds are not only economically important but also fascinating models for studying the adaptation of species in human-mediated environments. Aegilops tauschii is the D-genome donor species of common wheat but is also a weed that influences wheat production. How shading stress caused by adjacent wheat plants affects Ae. tauschii growth is a fundamental scientific question but is also important in agriculture, such as for weed control and wheat breeding. Result: The present study indicated that shade avoidance is a strategy of Ae. tauschii in response to shading stress. Ae. tauschii plants exhibited growth increases in specific organs, such as stem and leaf elongation, to avoid shading. However, these changes were accompanied by sacrificing the growth of other parts of the plants, such as a reduction in tiller number. The two reverse phenotype responses seem to be formed by systemically regulating the expression of different genes. Fifty-six genes involved in the regulation of cell division and cell expansion were found to be downregulated, and one key upstream negative regulator (RPK2) of cell division was upregulated under shading stress. On the other hand, the upregulated genes under shading stress were mainly enriched in protein serine/threonine kinase activity and carbon metabolism, which are associated with cell enlargement, signal transduction and energy supply. The transcription factor WRKY72 may be important in regulating genes in response to shading stress, which can be used as a prior candidate gene for further study on the genetic regulation of shade avoidance. Conclusions: This study sheds new light on the gene expression changes and molecular processes involved in the response and avoidance of Ae. tauschii to shading stress, which may aid more effective development of shading stress avoidance or cultivars in wheat and other crops in the future. [ABSTRACT FROM AUTHOR]

Introduction: Heavy metals refer to a group of metals or semi-metals whose atomic density is greater than 4 or 5 grams per cubic centimeter. What has caused concern about environmental pollution today is the accumulation of the chemical waste in the soil. Although copper is a micro-element for plants, it is toxic at high concentrations. This element causes structural, morphological, physiological, and biochemical changes in plants. Today, the phytoremediation technique is used as a suitable method for cleaning and removing water, soil, and air pollution. More than 400 species of overgrown plants have been identified. Studies have shown that Aegilops tauschii is a drought-resistant plant. Since, the stress of heavy metals can cause secondary drought stress.Material and Method: This research was performed to investigate the effect of the heavy metal copper on some physiological, morphological, and biochemical parameters of Aegilops tauschii. Therefore, the effect of different concentrations of copper (zero, 5, 25, and 125 micromolar) was studied on the physiological, biochemical, and morphological characteristics of 37 genotypes of Aegilops tauschii in the greenhouse condition.Result: The results showed that increasing copper concentrations decreased the amount of chlorophyll b, carotenoid, cell membrane stability, seed diameter, relative leaf water content, leaf retained water and single plant yield; while total chlorophyll, chlorophyll a, carbohydrate, proline, relative leaf water loss, root length, and root weight increased significantly. In terms of biochemical parameters, Genotypes 11, 58, and 85 with the highest values of morphological, physiological, and biochemical indices were resistant to copper. Among the mentioned genotypes, Genotype 58 with the highest yield as a resistant genotype, and Genotype 23, 28, 30, 52, 99 and 123 were subjected to copper stress more than other genotypes based on the morphological, physiological and biochemical indicators, among which Genotype 99 with the lowest yield could be introduced as the most sensitive genotype.Conclusion: According to the results, it seems that some genotypes of Aegilops tauschii were resistant to the heavy metal copper. Resistant genotypes could be recommended for phytoremediation in copper-contaminated areas.

Common hexaploid wheat (Triticum aestivum L.) belongs to the tribe of wheat, which includes representatives of the genera Triticum, Aegilops, Secale, Hordeum, etc. The genera Aegilops and Triticum repeatedly hybridized with each other in the process of evolution, including with the formation of polyploid forms that have the status of species and belong to the so-called Triticum–Aegilops alliance. With the development of a methodological possibilities, different approaches were used to determine the ancestors of certain species of this alliance, starting directly from interspecific crosses and cytogenetic methods and ending with whole genome sequencing of non-nuclear and nuclear genomes. It was established that the genome of the bread wheat T. aestivum (one of the main food crops of the world) consists of three related subgenomes that received the symbols A, B, and D. At present, only the donor of the D subgenome (which is Aegilops tauschii Coss) is reliably known. The T. urartu Thum. ex Gandil is presumably considered to be an ancestor of the A subgenome. Information about the donor of the B subgenome is less clear; however, it is most likely Ae. speltoides Tausch. or a species close to it. This review is devoted to the consideration of some old data on the putative donors of the bread wheat, which has (taking into account the maternal form) the BBAADD genome, and to the clarification of some phylogenetic relationships in the Triticum–Aegilops alliance in the light of new information obtained as a result of genome-wide studies of wheat. [ABSTRACT FROM AUTHOR]

In the face of climate change, bringing more useful alleles and genes from wild relatives of wheat is crucial to develop climate-resilient varieties. We used two populations of backcrossed recombinant inbred lines (BIL1 and BIL2), developed by crossing and backcrossing two intra-specifically diverse Aegilops tauschii accessions from lineage 1 and lineage 2, respectively, with the common wheat cultivar ‘Norin 61′. This study aimed to identify quantitative trait loci (QTLs) associated with heat stress (HS) tolerance. The two BILs were evaluated under heat stress environments in Sudan for phenology, plant height (PH), grain yield (GY), biomass (BIO), harvest index (HI), and thousand-kernel weight (TKW). Grain yield was significantly correlated with BIO and TKW under HS; therefore, the stress tolerance index (STI) was calculated for these traits as well as for GY. A total of 16 heat-tolerant lines were identified based on GY and STI-GY. The QTL analysis performed using inclusive composite interval mapping identified a total of 40 QTLs in BIL1 and 153 QTLs in BIL2 across all environments. We detected 39 QTLs associated with GY-STI, BIO-STI, and TKW-STI in both populations (14 in BIL1 and 25 in BIL2). The QTLs associated with STI were detected on chromosomes 1A, 3A, 5A, 2B, 4B, and all the D-subgenomes. We found that QTLs were detected only under HS for GY on chromosome 5A, TKW on 3B and 5B, PH on 3B and 4B, and grain filling duration on 2B. The higher number of QTLs identified in BIL2 for heat stress tolerance suggests the importance of assessing the effects of intraspecific variation of Ae. tauschii in wheat breeding as it could modulate the heat stress responses/adaptation. Our study provides useful genetic resources for uncovering heat-tolerant QTLs for wheat improvement for heat stress environments.

Abstract Background Aegilops tauschii Coss. as a donor of wheat D genome has an important role in wheat breeding programs. Genetic and phylogeographic diversity of 79 Ae. tauschii accessions collected from north and northwest of Iran were analyzed based on retroelement insertional polymorphisms using inter-retrotransposon amplified polymorphism (IRAP) and retrotransposon-microsatellite amplified polymorphism (REMAP) markers. Results In total, 306 and 151 polymorphic bands were amplified in IRAP and REMAP analyses, respectively. As a result, a high level of polymorphism was observed among the studied accessions as revealed by an average of 25.5 bands per primer/primer combination and mean PIC value of 0.47 in IRAP and an average of 25.16 bands per primer combination and mean PIC value of 0.47 in REMAP. Genetic relationships of the accessions were analyzed using distance- and model-based cluster analyses. Conclusion The result showed that genetic distance did not seem to be related to geographic distribution, and the accessions could be divided into three groups, which was further supported by principal coordinate analysis. These results on genetic diversity and population structure of Ae. tauschii in Iran should provide important knowledge on genetic resources and their applications in wheat breeding programs.

Aegilops tauschii is one of the malignant weeds that affect wheat production and is also the wild species ancestor of the D genome of hexaploid wheat (Triticum aestivum, AABBDD). It contains many disease resistance genes that have been lost in the long-term evolution of wheat and is an important genetic resource for the mining and utilization of wheat disease resistance genes. In recent years, the genome sequence of Aegilops tauschii has been preliminarily completed, which has laid a good foundation for the further exploration of wheat disease resistance genes in Aegilops tauschii. There are many studies on disease resistance genes in Aegilops tauschii; in order to provide better help for the disease resistance breeding of wheat, this paper analyzes and reviews the relationship between Aegilops tauschii and wheat, the research progress of Aegilops tauschii, the discovery of disease resistance genes from Aegilops tauschii, and the application of disease resistance genes from Aegilops tauschii to modern wheat breeding, providing a reference for the further exploration and utilization of Aegilops tauschii in wheat disease resistance breeding. [ABSTRACT FROM AUTHOR]

Archaeobotanical materials subject to aDNA analysis were recovered from Yumuktepe and Yenikapı, two important archaeological sites in Anatolia and date back to the Pottery Neolithic Period i.e., 7th millennium BC. Many charred ancient seeds representing various cereal species including a great number of wheat grains were documented in mentioned sites. Among the cereal seeds, charred wheat samples were tentatively identified as Triticum aestivum subsp. spelta L. or Triticum new glume wheat (NGW) or atypical emmer or naked wheat in Yumuktepe and Yenikapı showed similarities with the morphological characteristics of T. aestivum subsp. spelta wheat, but it was difficult to reach a firm conclusion. This study aimed to provide genetic data to enable more precise identification of charred wheat seeds using an ancient DNA (aDNA) approach. aDNAs were successfully extracted from the representative charred seeds of T. aestivum subsp. spelta or NGW or atypical emmer or naked wheat. The PCR amplification of 26SrDNA and IGS gene regions with aDNA was carried out and sequenced. The expected product sizes of IGS 158 bp for the D genome and 87 bp for the A or B genomes and DNA sequence comparisons with other wheat species revealed that T. aestivum subsp. spelta or NGW or atypical emmer or naked wheat samples included the D genome from Aegilops tauschii and is more likely to be T. aestivum subsp. spelta. The discovery of T. aestivum subsp. spelta grains in the Yenikapı and Yumuktepe suggest that the cultivation of hexaploid wheat was widespread. Further, spelta hulled wheat, which is the progenitor of the hexaploid wheat, might have been cultivated in these settlements. [ABSTRACT FROM AUTHOR]

Introduction: The establishment of invasive alien plants (IAPs) is primarily driven by climate warming and human activities, and their populations have a negative impact on agricultural economics, ecological systems, and human health. Lolium temulentum and Aegilops tauschii are critical IAPs in China because they reduce the quality of cereal grains and decrease wheat yields. Lolium temulentum is a winter-temperate weed that spreads easily and is poisonous to humans and animals. Aegilops tauschii is resistant to herbicides, has a high reproductive rate, and frequently grows in wheat. Both species have been listed in the Ministry of Agriculture and Rural Affairs of the People's Republic of China's management catalog since 2006. Methods: In the present study, the historical occurrence and invasion of each species were collected and reconstructed, which showed that the population outbreak of L. temulentum began in 2010, whereas that of A. tauschii began in 2000. Using the optimal MaxEnt model, the geographical distributions of L. temulentum and A. tauschii were predicted based on screened species occurrences and environmental variables under the current and three future scenarios in the 2030s and 2050s (i.e., SSP1-2.6, SSP2-4.5, and SSP5-8.5). Results: The mean AUC values were 0.867 and 0.931 for L. temulentum and A. tauschii, respectively. Human influence index (HII), mean temperature of coldest quarter (bio11), and precipitation of coldest quarter (bio19) were the most significant variables for L. temulentum, whereas human influence index, temperature seasonality (standard deviation×100) (bio4), and annual mean temperature (bio1) were the critical environmental variables for A. tauschi. Suitable habitat areas in China for L. temulentum and A. tauschii currently covered total areas of 125 × 104 and 235 × 104 km2, respectively. Future suitable areas of L. temulentum reached the maximum under SSP2-4.5, from 2021 to 2060, whereas for A. tauschii they reached the maximum under SSP5-8.5, from 2021 to 2060. Furthermore, the overlap area under the current climate conditions for L. temulentum and A. tauschii was approximately 90 × 104 km2, mainly located in Hubei, Anhui, Jiangsu, Shandong, Henan, Shaanxi, Shanxi, and Hebei. The overlap areas decreased in the 2030s, increased in the 2050s, and reached a maximum under SSP1-2.6 (or SSP2-4.5) with an approximate area of 104 × 104 km2. The centroid of L. temulentum in Henan was transferred to the southwest, whereas for A. tauschii it transferred to higher latitudes in the northeast. Discussion: Our findings provide a practical reference for the early warning, control, and management of these two destructive IAP populations in China. [ABSTRACT FROM AUTHOR]

The relevance of this research is determined by the prevalence of cereal crops, particularly common wheat, one of the ancestors of which is Aegilops tauschii. The development of new markers that can be used to study the genetic diversity of cereals is a current issue today. The aim of this study was to develop intron length polymorphism (ILP) markers to investigate the intron length polymorphism of PFKFB4 and RAS genes in Aegilops tauschii, and to assess the potential use of the developed markers for genetic differentiation of Ae. tauschii and Ae. biuncialis. EST sequences were obtained using the NCBI database, and online tools such as CDHIT, BLAST, and Primer3Plus were employed for primer design. Molecular markers, Aet_ILP_1.1, Aet_ILP_1.2, and Aet_ILP_2, were developed and their efficiency was tested on samples of Ae. tauschii and Ae. biuncialis. Amplified fragments were separated using denaturing polyacrylamide gel electrophoresis and silver staining was performed. The Aet_ILP_1.1 marker differentiated fifteen Ae. biuncialis samples into two groups. The use of the Aet_ILP_1.2 marker revealed additional amplicons in certain Ae. tauschii and Ae. biuncialis samples on electropherograms. The Aet_ILP_2 marker visualized amplicons only in Ae. biuncialis samples. Overall, the results indicate a low level of intraspecific genetic variability in Ae. tauschii using the developed markers, however, they can be effectively utilized for assessing interspecific differentiation between Ae. tauschii and Ae. biuncialis. [ABSTRACT FROM AUTHOR]

Summary: Aegilops tauschii is the diploid progenitor of the wheat D subgenome and a valuable resource for wheat breeding, yet, genetic analysis of resistance against Fusarium head blight (FHB) and the major Fusarium mycotoxin deoxynivalenol (DON) is lacking. We treated a panel of 147 Ae. tauschii accessions with either Fusarium graminearum spores or DON solution and recorded the associated disease spread or toxin‐induced bleaching. A k‐mer‐based association mapping pipeline dissected the genetic basis of resistance and identified candidate genes. After DON infiltration nine accessions revealed severe bleaching symptoms concomitant with lower conversion rates of DON into the non‐toxic DON‐3‐O‐glucoside. We identified the gene AET5Gv20385300 on chromosome 5D encoding a uridine diphosphate (UDP)‐glucosyltransferase (UGT) as the causal variant and the mutant allele resulting in a truncated protein was only found in the nine susceptible accessions. This UGT is also polymorphic in hexaploid wheat and when expressed in Saccharomyces cerevisiae only the full‐length gene conferred resistance against DON. Analysing the D subgenome helped to elucidate the genetic control of FHB resistance and identified a UGT involved in DON detoxification in Ae. tauschii and hexaploid wheat. This resistance mechanism is highly conserved since the UGT is orthologous to the barley UGT HvUGT13248 indicating descent from a common ancestor of wheat and barley. [ABSTRACT FROM AUTHOR]

Identification of resistance gene sources in seedling and adult plant stages is important to developing durable wheat cultivars. In this study, 100 genotypes of Aegilops tauschii, collected from natural habitats were evaluated in the experimental field of the Iraqi-mahaleh, Gorgan. Seeds were planted on one meter length lines and inoculated with Golestan leaf rust pathotypes in a randomized complete block design with three replications. The reaction of genotypes was also evaluated in greenhouse, by six Iranian pathotypes based on a completely randomized design with two replications in seed and plant improvement institute (SPII). To evaluate resistance in filed, we used infection type, AUDPC, final disease severity and coefficient of infection indices. The results showed that in greenhouse, the frequency of resistant, moderately resistant, moderately susceptible and susceptible genotypes were 7, 13, 13 and 67 percent, respectively. In field, the regarding frequencies were 14, 49, 7 and 30 percent. The correlation coefficient between final severity of infection, with the values of coefficient of infection and area under the disease progress curve, were 0.97 and 0.95, respectively. Accordingly, 57 genotypes with the desired characteristics, namely final infection intensity of 3.5-40, infection coefficient of 1.4-30 and rAUDPC, 1-32% were identified with MS and MR responses for resistance. Forty-six genotypes were susceptible in seedling stage and resistant in adult plant stage. Some genotypes originated from Afghanistan, Azerbaijan, China and Uzbekistan were resistant to all isolates which could be considered as appropriate sources of resistance to leaf rust disease for breeding of cultivated wheat species. [ABSTRACT FROM AUTHOR]

The wheat leaf rust resistance gene Lr1 encodes a typical coiled-coil nucleotide-binding site leucine-rich repeat (CC-NBS-LRR) of resistance protein containing 1 344 amino acids. WR003, a cleaved amplified polymorphic sequence (CAPS) marker is derived from the LRR regions of Lr1. In this study, a worldwide collection of 120 Aegilops tauschii accessions and 282 hexaploid wheat varieties was screened for Lr1 alleles using WR003, and the specificity of WR003 for Lr1 was confirmed by pathogenicity tests and genotype analysis. The sequence alignment and phylogenetic tree analysis of 38 Lr1 haplotypes provided a further view of the molecular evolution of Lr1. The results showed that there were very few polymorphisms between the Lr1 alleles from Ae. tauschii and hexaploid wheat with the same resistance phenotype. The polymorphisms of the Lr1 haplotypes were mainly between the different resistance lines, rather than between the different ploidy levels. These results indicate that Lr1 originated from Ae. tauschii and differentiated into resistant and susceptible genotypes before its introgression into hexaploid wheat. Therefore, it is likely that wheat Lr1 has at least two major variants for disease resistance and susceptibility, and except for certain point mutations, few gene conversions and genetic re-combinations occurred during the hexaploid wheat domestication. [ABSTRACT FROM AUTHOR]

The duration of the vegetative period is an important agronomic characteristic of cereal crops. It is mainly influenced by the Vrn (response to vernalization) and Ppd (response to photoperiod) genes. In this work, we searched for alleles of several known genes of these two systems of response to external conditions in 15 accessions of Aegilops tauschii Coss. (syn. Ae. squarrosa L.), with the aim of studying the impact these alleles have on the vegetative period duration and growth habit. As a result, three allelic variants have been found for the Vrn-D1 gene: (i) one intact (winter type), (ii) one with a 5437 bp deletion in the first intron and (iii) one previously undescribed allele with a 3273 bp deletion in the first intron. It has been shown that the spring growth habit of Ae. tauschii can be developed due to the presence of a new allele of the Vrn-D1 gene. Significant differences in expression levels between the new allelic variant of the Vrn-D1 gene and the intact allele vrn-D1 were confirmed by qPCR. The new allele can be introgressed into common wheat to enhance the biodiversity of the spring growth habit and vegetative period duration of plants.

Improving end-use quality and disease resistance are important goals in wheat breeding. The genetic loci controlling these traits are highly complex, consisting of large families of prolamin and resistance genes with members present in all three homeologous A, B, and D genomes in hexaploid bread wheat. Here, orthologous regions harboring both prolamin and resistance gene loci were reconstructed and compared to understand gene duplication and evolution in different wheat genomes. Comparison of the two orthologous D regions from the hexaploid wheat Chinese Spring and the diploid progenitor Aegilops tauschii revealed their considerable difference due to the presence of five large structural variations with sizes ranging from 100 kb to 2 Mb. As a result, 44% of the Ae. tauschii and 71% of the Chinese Spring sequences in the analyzed regions, including 79 genes, are not shared. Gene rearrangement events, including differential gene duplication and deletion in the A, B, and D regions, have resulted in considerable erosion of gene collinearity in the analyzed regions, suggesting rapid evolution of prolamin and resistance gene families after the separation of the three wheat genomes. We hypothesize that this fast evolution is attributed to the co-evolution of the two gene families dispersed within a high recombination region. The identification of a full set of prolamin genes facilitated transcriptome profiling and revealed that the A genome contributes the least to prolamin expression because of its smaller number of expressed intact genes and their low expression levels, while the B and D genomes contribute similarly.