Aegilops Tauschii Research Articles

Identification of synthetic wheat lines with broadly effective stripe rust resistance

Wheat stripe/yellow rust (WYR), caused by Puccinia striiformis f. sp. tritici (Pst), is a major constraint in global wheat production. A set of 766 hexaploid synthetic wheat lines, including primary crosses of Triticum turgidum x Aegilops tauschii and their derivatives, were screened in artificially rust inoculated field nurseries for three seasons. From this set, a core set of 94 non-lodging lines with unique pedigrees and resistance to Pst that was consistent across years was established. The core set was tested for adult plant field response under field conditions for three seasons in Australia and at least one crop season in Ethiopia, India, Kenya, Nepal and Pakistan. It was also challenged with an array of well-defined Pst pathotypes at seedling growth stages in the greenhouse, and genotyped with molecular markers linked to the adult plant resistance (APR) genes Yr18, Yr36 and Yr46. Combined analysis of field rust responses, multi-pathotype seedling phenotyping and marker genotyping resolved seven classes of Pst resistance: uncatalogued (new) APR (UAPR, 11%), uncatalogued seedling resistance (USR, 46%), known seedling resistance (KSR, 5%), KSR + USR (2%), Yr18 + UAPR (4%), Yr18 + USR (29%) and Yr18 + KSR (3%). A majority of the lines carrying UAPR and USR either singly or in combination showed high levels of field resistance across all field sites and years of testing, demonstrating that these lines represent a valuable resource for breeding wheat for resistance to Pst.

D genome acquisition and breeding have had a significant impact on interaction of wheat with ACC deaminase producers in soil or ACC deaminase potential activity in the rhizosphere

Rhizosphere functioning depends on plant traits, but the underlying genotypic properties are poorly understood. Wheat has undergone several domestication events combined with genomic hybridization, including the acquisition by Triticum dicoccon (AABB genome) of the D genome from Aegilops tauschii, resulting into bread wheat Triticum aestivum (AABBDD genome). The D genome is likely to modulate the functioning of beneficial wheat-microbe interactions, but data are needed to substantiate this. Here, we tested the hypothesis that genome D is important for soil interactions of wheat with 1-aminocyclopropane-1-carboxylate (ACC) deaminase producers, a key microbial functional group that enhances plant performance by fine-tuning ethylene metabolism in roots. A range of wheat lines from T. aestivum (AABBDD), T. diccocon (AABB) and Ae. tauschii (DD) were compared based on abundance (qPCR on acdS gene marker), diversity (Illumina MiSeq) and potential ACC deaminase activity (colorimetric assays) of ACC deaminase producers in the rhizosphere. Results showed that the abundance of ACC deaminase producers was lower for D-genome wheats than D-negative T. dicoccon at 40 days, but ACC deaminase potential activity in the rhizosphere was lower for D-genome Ae. tauschii and T. aestivum landraces than T. aestivum cultivars (recent and old), while D-negative T. dicoccon was in between. Rhizosphere community structure of Ae. tauschii and T. dicoccon differed from that of T. aestivum, and differences occurred also between various genotype categories of T. aestivum. Overall, the acquisition of the D genome has had a negative impact on the ability of wheat to recruit ACC deaminase producers in soil, but bread wheats resulting from recent breeding displayed improved ACC deaminase activity in the rhizosphere.

A new winter wheat genetic resource harbors untapped diversity from synthetic hexaploid wheat

Key messageThe NIAB_WW_SHW_NAM population, a large nested association mapping panel, is a useful resource for mapping QTL from synthetic hexaploid wheat that can improve modern elite wheat cultivars.The allelic richness harbored in progenitors of hexaploid bread wheat (Triticum aestivum L.) is a useful resource for addressing the genetic diversity bottleneck in modern cultivars. Synthetic hexaploid wheat (SHW) is created through resynthesis of the hybridisation events between the tetraploid (Triticum turgidum subsp. durum Desf.) and diploid (Aegilops tauschii Coss.) bread wheat progenitors. We developed a large and diverse winter wheat nested association mapping (NAM) population (termed the NIAB_WW_SHW_NAM) consisting of 3241 genotypes derived from 54 nested back-cross 1 (BC1) populations, each formed via back-crossing a different primary SHW into the UK winter wheat cultivar ‘Robigus’. The primary SHW lines were created using 15 T. durum donors and 47 Ae. tauschii accessions that spanned the lineages and geographical range of the species. Primary SHW parents were typically earlier flowering, taller and showed better resistance to yellow rust infection (Yr) than ‘Robigus’. The NIAB_WW_SHW_NAM population was genotyped using a single nucleotide polymorphism (SNP) array and 27 quantitative trait loci (QTLs) were detected for flowering time, plant height and Yr resistance. Across multiple field trials, a QTL for Yr resistance was found on chromosome 4D that corresponded to the Yr28 resistance gene previously reported in other SHW lines. These results demonstrate the value of the NIAB_WW_SHW_NAM population for genetic mapping and provide the first evidence of Yr28 working in current UK environments and genetic backgrounds. These examples, coupled with the evidence of commercial wheat breeders selecting promising genotypes, highlight the potential value of the NIAB_WW_SHW_NAM to variety improvement.

Variation of TaMyb10 and their function on grain color and pre-harvest sprouting resistance of wheat.

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.

Identifying novel sources of resistance to wheat stem sawfly in five wild wheat species.

The wheat stem sawfly (WSS, Cephus cinctus) is a major pest of wheat (Triticum aestivum) and can cause significant yield losses. WSS damage results from stem boring and/or cutting, leading to the lodging of wheat plants. Although solid-stem wheat genotypes can effectively reduce larval survival, they may have lower yields than hollow-stem genotypes and show inconsistent solidness expression. Because of limited resistance sources to WSS, evaluating diverse wheat germplasm for novel resistance genes is crucial. We evaluated 91 accessions across five wild wheat species (Triticum monococcum, T. urartu, T. turgidum, T. timopheevii, and Aegilops tauschii) and common wheat cultivars (T. aestivum) for antixenosis (host selection) and antibiosis (host suitability) to WSS. Host selection was measured as the number of eggs after adult oviposition, and host suitability was determined by examining the presence or absence of larval infestation within the stem. The plants were grown in the greenhouse and brought to the field for WSS infestation. In addition, a phylogenetic analysis was performed to determine the relationship between the WSS traits and phylogenetic clustering. Overall, Ae. tauschii, T. turgidum and T. urartu had lower egg counts and larval infestation than T. monococcum, and T. timopheevii. T. monococcum, T. timopheevii, T. turgidum, and T. urartu had lower larval weights compared with T. aestivum. This study shows that wild relatives of wheat could be a valuable source of alleles for enhancing resistance to WSS and identifies specific germplasm resources that may be useful for breeding. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Transcriptome analysis in Aegilops tauschii unravels further insights into genetic control of stripe rust resistance.

The Aegilops tauschii resistant accession prevented the pathogen colonization by controlling the sugar flow and triggering the hypersensitive reaction. This study suggested that NBS-LRRs probably induce resistance through bHLH by controlling JA- and SA-dependent pathways. Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst) is one of wheat's most destructive fungal diseases that causes a severe yield reduction worldwide. The most effective and economically-friendly strategy to manage this disease is genetic resistance which can be achieved through deploying new and effective resistance genes. Aegilops tauschii, due to its small genome and co-evolution with Pst, can provide detailed information about underlying resistance mechanisms. Hence, we used RNA-sequencing approach to identify the transcriptome variations of two contrasting resistant and susceptible Ae. tauschii accessions in interaction with Pst and differentially expressed genes (DEGs) for resistance to stripe rust. Gene ontology, pathway analysis, and search for functional domains, transcription regulators, resistance genes, and protein-protein interactions were used to interpret the results. The genes encoding NBS-LRR, CC-NBS-kinase, and phenylalanine ammonia-lyase, basic helix-loop-helix (bHLH)-, basic-leucinezipper (bZIP)-, APETALA2 (AP2)-, auxin response factor (ARF)-, GATA-, and LSD-like transcription factors were up-regulated exclusively in the resistant accession. The key genes involved in response to salicylic acid, amino sugar and nucleotide sugar metabolism, and hypersensitive response contributed to plant defense against stripe rust. The activation of jasmonic acid biosynthesis and starch and sucrose metabolism pathways under Pst infection in the susceptible accession explained the colonization of the host. Overall, this study can fill the gaps in the literature on host-pathogen interaction and enrich the Ae. tauschii transcriptome sequence information. It also suggests candidate genes that could guide future breeding programs attempting to develop rust-resistant cultivars.

Heat Stress-Tolerant Quantitative Trait Loci Identified Using Backcrossed Recombinant Inbred Lines Derived from Intra-Specifically Diverse Aegilops tauschii Accessions

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.

Domestication caused taxonomical and functional shifts in the wheat rhizosphere microbiota, and weakened the natural bacterial biocontrol against fungal pathogens

Modern crops might have lost some of their functional traits, required for interacting with beneficial microbes, as a result of the genotypic/phenotypic modifications that occurred during domestication. Here, we studied the bacterial and fungal microbiota in the rhizosphere of two cultivated wheat species (Triticum aestivum and T. durum) and their respective ancestors (Aegilops tauschii and T. dicoccoides), in three experimental fields, by using metabarcoding of 16S rRNA genes and ITS2, coupled with co-occurrence network analysis. Moreover, the abundance of bacterial genes involved in N- and P-cycles was estimated by quantitative PCR, and urease, alkaline phosphatase and phosphomonoesterase activities were assessed by enzymatic tests. The relationships between microbiota and environmental metadata were tested by correlation analysis. The assemblage of core microbiota was affected by both site and plant species. No significant differences in the abundance of potential fungal pathogens between wild and cultivated wheat species were found; however, co-occurrence analysis showed more bacterial–fungal negative correlations in the wild species. Concerning functions, the nitrogen denitrification nirS gene was consistently more abundant in the rhizosphere of A. tauschii than T. aestivum. Urease activity was higher in the rhizosphere of each wild wheat species in at least two of the research locations. Several microbiota members, including potentially beneficial taxa such as Lysobacter and new taxa such as Blastocatellaceae, were found to be strongly correlated to rhizospheric soil metadata. Our results showed that a functional microbiome shift occurred as a result of wheat domestication. Notably, these changes also included the reduction of the natural biocontrol potential of rhizosphere-associated bacteria against pathogenic fungi, suggesting that domestication disrupted the equilibrium of plant-microbe relationships that had been established during million years of co-evolution.

TauL1, TauL2 and TauL3 gene-pools of Aegilops tauschii essentially differ in their genetic expression patterns

Aegilops tauschii is a wild diploid goat-grass which occupies a vast range in Central Eurasia and comprises three different gene-pools: TauL1, TauL2, and TauL3. Multivariate statistical analysis of the transcriptomes from the leaf tissue of 40 A. tauschii accessions, 18 of TauL1, 20 of TauL2, and 2 of TauL3, revealed that the gene-pools of A. tauschii distinctly and essentially differ in their genetic expression patterns. Statistically significant differential gene expression of 2349, 376, and 272 were observed between TauL1 and TauL2; TauL1 and TauL3; TauL2 and TauL3, respectively. These findings indicate substantial adaptive intraspecies divergence in A. tauschii.

Mining Aegilops tauschii genetic diversity in the background of bread wheat revealed a novel QTL for seed dormancy.

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.

A platform for whole-genome speed introgression from Aegilops tauschii to wheat for breeding future crops.

Breeding new and sustainable crop cultivars of high yields and desirable traits has been a major challenge for ensuring food security for the growing global human population. For polyploid crops such as wheat, introducing genetic variation from wild relatives of its subgenomes is a key strategy to improve the quality of their breeding pools. Over the past decades, considerable progress has been made in speed breeding, genome sequencing, high-throughput phenotyping and genomics-assisted breeding, which now allows us to realize whole-genome introgression from wild relatives to modern crops. Here, we present a standardized protocol to rapidly introgress the entire genome of Aegilops tauschii, the progenitor of the D subgenome of bread wheat, into elite wheat backgrounds. This protocol integrates multiple modern high-throughput technologies and includes three major phases: development of synthetic octaploid wheat, generation of hexaploid A. tauschii-wheat introgression lines (A-WIs) and homozygosis of the generated A-WIs. Our approach readily generates stable introgression lines in 2 y, thus greatly accelerating the generation of A-WIs and the introduction of desirable genes from A. tauschii to wheat cultivars. These A-WIs are valuable for wheat-breeding programs and functional gene discovery. The current protocol can be easily modified and used for introgressing the genomes of wild relatives to other polyploid crops.

Molecular mechanism analysis of ZmRL6 positively regulating drought stress tolerance in maize

MYB-related genes, a subclass of MYB transcription factor family, have been documented to play important roles in biological processes such as secondary metabolism and stress responses that affect plant growth and development. However, the regulatory roles of MYB-related genes in drought stress response remain unclear in maize. In this study, we discovered that a 1R-MYB gene, ZmRL6, encodes a 96-amino acid protein and is highly drought-inducible. We also found that it is conserved in both barley (Hordeum vulgare L.) and Aegilops tauschii. Furthermore, we observed that overexpression of ZmRL6 can enhance drought tolerance while knock-out of ZmRL6 by CRISPR-Cas9 results in drought hypersensitivity. DAP-seq analyses additionally revealed the ZmRL6 target genes mainly contain ACCGTT, TTACCAAAC and AGCCCGAG motifs in their promoters. By combining RNA-seq and DAP-seq results together, we subsequently identified eight novel target genes of ZmRL6 that are involved in maize's hormone signal transduction, sugar metabolism, lignin synthesis, and redox signaling/oxidative stress. Collectively, our data provided insights into the roles of ZmRL6 in maize’s drought response.

AEGILOPS L. GENETIC DIVERSITY IN SOUTHWESTERN REGION OF UZBEKISTAN

As wheat donors, wild species of the genus Aegilops L. play a vital role in practical breeding to improve wheat production because of their strong relationship and wide genetic diversity. Using nine simple sequence repeat (SSR) markers helped assess the genetic diversity in 96 collected samples of four species belonging to the genus Aegilops, i.e., Aegilops tauschii Coss (D), Ae. cylindrica Host (CD), Ae. crassa Boiss (DDM), and Ae. triuncialis L. (UC). The said collection came from 21 sites of various expeditions located in three regions of Southwestern Uzbekistan (Samarkand, Urgut, Kitab, and Shakhrisabz regions). Generally, 102 distinct alleles were found, with an average of 11.33 alleles per primer. The total number of species-specific amplicons was 35. The polymorphism detected varied from 28.6% (for the WSP107 primer) to 77.0% (for the WSP130 and WSP192 primers). The mean values of polymorphism information content (PIC) and expected heterozygosity (Ho) for all samples were 0.675 and 0.527, respectively. Based on nine SSR markers, on average, the genetic distance indices (GD) varied from 0.63 to 0.77. The highest genetic similarity (GD = 0.77) recorded occurred between the species Ae. crassa and Ae. cylindrica, whereas the least (GD = 0.48), between Ae. cylindrica and Ae. triuncialis with their taxonomic classification. Genus Aegilops samples from the same region often attain an identical subgrouping, which might be due to relatedness by genetic parameters. The gene pool of native species of the genus Aegilops from the Southwestern region of Uzbekistan may provide suitable alleles for wheat improvement and adaptation in the future.

Analysis of the Structural Organization and Expression of the Vrn-D1 Gene Controlling Growth Habit (Spring vs. Winter) in Aegilops tauschii Coss.

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.

The Genome-Wide Identification, Characterization, and Expression Analysis of the Strictosidine Synthase-like Family in Maize (Zea mays L.).

Maize is often subjected to various environmental stresses. The strictosidine synthase-like (SSL) family is thought to catalyze the key step in the monoterpene alkaloids synthesis pathway in response to environmental stresses. However, the role of ZmSSL genes in maize growth and development and its response to stresses is unknown. Herein, we undertook the systematic identification and analysis of maize SSL genes. Twenty SSL genes were identified in the maize genome. Except for chromosomes 3, 5, 6, and 10, they were unevenly distributed on the remaining 6 chromosomes. A total of 105 SSL genes from maize, sorghum, rice, Aegilops tauschii, and Arabidopsis were divided into five evolutionary groups, and ZmSSL gene structures and conserved protein motifs in the same group were similar. A collinearity analysis showed that tandem duplication plays an important role in the evolution of the SSL family in maize, and ZmSSL genes share more collinear genes in crops (maize, sorghum, rice, and Ae. tauschii) than in Arabidopsis. Cis-element analysis in the ZmSSL gene promoter region revealed that most genes contained many development and stress response elements. We evaluated the expression levels of ZmSSL genes under normal conditions and stress treatments. ZmSSL4-9 were widely expressed in different tissues and were positively or negatively regulated by heat, cold, and infection stress from Colletotrichum graminicola and Cercospora zeina. Moreover, ZmSSL4 and ZmSSL5 were localized in the chloroplast. Taken together, we provide insight into the evolutionary relationships of the ZmSSL genes, which would be useful to further identify the potential functions of ZmSSLs in maize.

Genome-wide identification, phylogenetic and expression pattern analysis of HSF family genes in the Rye (Secale cereale L.)

BackgroundHeat shock factor (HSF), a typical class of transcription factors in plants, has played an essential role in plant growth and developmental stages, signal transduction, and response to biotic and abiotic stresses. The HSF genes families has been identified and characterized in many species through leveraging whole genome sequencing (WGS). However, the identification and systematic analysis of HSF family genes in Rye is limited.ResultsIn this study, 31 HSF genes were identified in Rye, which were unevenly distributed on seven chromosomes. Based on the homology of A. thaliana, we analyzed the number of conserved domains and gene structures of ScHSF genes that were classified into seven subfamilies. To better understand the developmental mechanisms of ScHSF family during evolution, we selected one monocotyledon (Arabidopsis thaliana) and five (Triticum aestivum L., Hordeum vulgare L., Oryza sativa L., Zea mays L., and Aegilops tauschii Coss.) specific representative dicotyledons associated with Rye for comparative homology mapping. The results showed that fragment replication events modulated the expansion of the ScHSF genes family. In addition, interactions between ScHSF proteins and promoters containing hormone- and stress-responsive cis-acting elements suggest that the regulation of ScHSF expression was complex. A total of 15 representative genes were targeted from seven subfamilies to characterize their gene expression responses in different tissues, fruit developmental stages, three hormones, and six different abiotic stresses.ConclusionsThis study demonstrated that ScHSF genes, especially ScHSF1 and ScHSF3, played a key role in Rye development and its response to various hormones and abiotic stresses. These results provided new insights into the evolution of HSF genes in Rye, which could help the success of molecular breeding in Rye.

Investigating the dynamic responses of Aegilops tauschii Coss. to salinity, drought, and nitrogen stress: a comprehensive study of competitive growth and biochemical and molecular pathways.

Aegilops tauschii (Coss.) is a highly deleterious, rapidly proliferating weed within the wheat, and its DD genome composition exhibits adaptability toward diverse abiotic stresses and demonstrates heightened efficacy in nutrient utilization. Current study investigated different variegated impacts of distinct nitrogen concentrations with varied plant densities, scrutinizing the behavior of Ae. tauschii under various salinity and drought stress levels through multiple physiological, biochemical, and molecular pathways. Different physiological parameters attaining high growth with different plant density and different nitrogen availability levels increased Ae. tauschii dominancy. Conversely, under the duress of salinity and drought, Ae. tauschii showcased an enhanced performance through a comprehensive array of physiological and biochemical parameters, including catalase, peroxidase, malondialdehyde, and proline content. Notably, salinity-associated traits such as sodium, potassium, and the sodium-potassium ratio exhibited significant variations and demonstrated remarkable tolerance capabilities. In the domain of molecular pathways, the HKT and DREB genes have displayed a remarkable upregulation, showcasing a comparatively elevated expression profile in reaction to different levels of salinity and drought-induced stress. Without a doubt, this information will make a substantial contribution to the understanding of the fundamental behavioral tendencies and the efficiency of nutrient utilization in Ae. tauschii. Moreover, it will offer innovative viewpoints for integrated management, thereby enabling the enhancement of strategies for adept control and alleviation.

Fine mapping of two recessive powdery mildew resistance genes from Aegilops tauschii accession CIae8.

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%. The identification of new Pm resistance genes will enrich the genetic diversity of wheat breeding for Pm resistance. Aegilops tauschii is the ancestor donor of sub-genome D of hexaploid wheat. It provides beneficial genes that can be easily transferred into wheat by producing synthetic hexaploid wheat followed by genetic recombination. We assessed the Pm resistance level of 35 Ae. tauschii accessions from different origins. Accession CIae8 exhibited high Pm resistance. Inheritance analysis and gene mapping were performed using F2 and F2:3 populations derived from the cross between CIae8 and a Pm susceptible accession PI574467. The Pm resistance of CIae8 was controlled by two independent recessive genes. Bulked segregate analysis using a 55K SNP array revealed the SNPs were mainly enriched into genome regions, i.e. 2DS (13.5-20Mb) and 7DS (4.0-15.5Mb). The Pm resistance loci were named as pmAeCIae8_2DS and pmAeCIae8_7DS, respectively. By recombinant screening, we narrowed the pmAeCIae8_2DS into a 370-kb interval flanked by markers CINAU-AE7800 (14.89Mb) and CINAU-AE20 (15.26Mb), and narrowed the pmAeCIae8_7DS into a 260-kb interval flanked by markers CINAU-AE58 (4.72Mb) and CINAU-AE25 (4.98Mb). The molecular markers closely linked with the resistance loci were developed, and two synthesized hexaploid wheat (SHW) lines were produced. These laid the foundation for cloning of the two resistance loci and for transferring the resistance into common wheat.

Algorithm for creating ILP markers for molecular genetic analysis of Triticum durum and other types of cereals

Aim. Development of an algorithm for creating ILP markers suitable for breeding studies of durum wheat (Triticum durum) and some other types of cereals. Methods. Use of classical bioinformatics tools to locate potential intron sites of target genes in T. durum suitable for use as ILP markers based on homology of T. durum contigs and rice (Oryza sativa) coding sequences. Analysis of exon-intron structure of homologous genes in O. sativa, Hordeum vulgare, Aegilops tauschii and Triricum aestivum followed by selection of appropriate primers for potential ILP markers. Results. A number of potential location sites of target introns in T. durum contig sequences were identified. Degenerate primers were designed for them, taking into account the analysis of the exon-intron structure of the corresponding homologous genes in O. sativa, H. vulgare, A. tauschii and T. aestivum. Conclusions. An algorithm for the creation of ILP markers was developed, which can be used in molecular genetic studies of plants in the case of the absence or incomplete sequenced genome of the studied species and the lack of information about the exon-intron structure of their genes. A number of potential ILP markers that can be used for cereals, in particular T. durum, have been identified.

Effect of saline–alkaline stresses on the interspecific competition between Aegilops tauschii and Triticum aestivum

Soil salinization has produced severe consequences on global agricultural production and ecological environment. Based on the features of saline soils in China, through mixed NaCl, NaHCO3, Na2SO4, and Na2CO3 at varying ratios to simulate the salinity–alkalinity stress and conducted a controlled pot experiment using De Wit replacement method. The effects of salinity–alkalinity stress on the growth of Aegilops tauschii and its competition with wheat were explored to provide a reference for the study of invasion mechanism of A. tauschii. The result showed that, the salinity–alkalinity stress inhibited the growth and development of both the species, which was reflected in plant height, leaf area and total biomass indicators. Secondly, the tolerance of both plant species to salinity–alkalinity stress was improved by increasing the superoxide dismutase (SOD) activity and the proline content. However, as the salinity–alkalinity stress was exacerbated, the relative conductivity and thiobarbituric acid (TBARS) content increased significantly in both the species. As suggested by the level of increase in SOD activity, proline content, relative conductivity, and TBARS content, A. tauschii was more tolerant to the salinity–alkalinity stress than wheat. Finally, it can be seen from the value of the competition balance index, A. tauschii was still more competitive than wheat even under salinity–alkalinity stress. In summary, A. tauschii was more tolerant of the salinity–alkalinity stress than wheat through the favorable adjustment of morphology, biomass allocation pattern, and physiological features, which is expected to increase its invasion damage to wheat.