Karyotype establishment and development of specific molecular markers of Aegilops geniculata Roth based on SLAF-seq

The constant evolution of pathogens poses a threat to wheat resistance against diseases,endangering food security.Developing resistant wheat varieties is the most practical approach for circumventing this problem.As a close relative of wheat,Aegilops geniculata,particularly accession SY159,has evolved numerous beneficial traits that could be applied to improve wheat.In this study,we established the karyotype of SY159 by fluorescence in situ hybridization(FISH)using the oligonucleotide probes Oligo-pTa535 and Oligo-pSc119.2 and a complete set of wheat–Ae.geniculata accession TA2899 addition lines as a reference.Using specific-locus amplified fragment sequencing(SLAF-seq)technology,400 specific markers were established for detecting the SY159 chromosomes with efficiencies reaching 81.5%.The SY159-specific markers were used to classify the different homologous groups of SY159 against the wheat-Ae.geniculata addition lines.We used these specific markers on the 7Mg chromosome after classification,and successfully confirmed their suitability for studying the different chromosomes of SY159.This study provides a foundation for accelerating the application of SY159 in genetic breeding programs designed to improve wheat.

Introgression of QTL from Aegilops tauschii enhances yield-related traits in common wheat

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.

Investigation of Aegilops umbellulata for stripe rust resistance,heading date,and the contents of iron,zinc,and gluten protein

Aegilops umbellulata(UU)is a wheat wild relative that has potential use in the genetic improvement of wheat.In this study,46 Ae.umbellulata accessions were investigated for stripe rust resistance,heading date(HD),and the contents of iron(Fe),zinc(Zn),and seed gluten proteins.Forty-two of the accessions were classified as resistant to stripe rust,while the other four accessions were classified as susceptible to stripe rust in four environments.The average HD of Ae.umbellulata was significantly longer than that of three common wheat cultivars(180.9 d vs.137.0 d),with the exception of PI226500(138.9 d).The Ae.umbellulata accessions also showed high variability in Fe(69.74-348.09 mg kg^(-1))and Zn(49.83-101.65 mg kg^(-1))contents.Three accessions(viz.,PI542362,PI542363,and PI554399)showed relatively higher Fe(230.96-348.09 mg kg^(-1))and Zn(92.46-101.65 mg kg^(-1))contents than the others.The Fe content of Ae.umbellulata was similar to those of Ae.comosa and Ae.markgrafii but higher than those of Ae.tauschii and common wheat.Aegilops umbellulata showed a higher Zn content than Ae.tauschii,Ae.comosa,and common wheat,but a lower content than Ae.markgrafii.Furthermore,Ae.umbellulata had the highest proportion of γ-gliadin among all the species investigated(Ae.umbellulata vs.other species=mean 72.11%vs.49.37%;range:55.33-86.99%vs.29.60-67.91%).These results demonstrated that Ae.umbellulata exhibits great diversity in the investigated traits,so it can provide a potential gene pool for the genetic improvement of these traits in wheat.

Development and characterization of wheat–Aegilops kotschyi 1U^(k)(1A)substitution line with positive dough quality parameters

Exploring novel high molecular weight glutenin subunits(HMW-GSs)from wild related species is a strategy to improve wheat processing quality.The objective of the present investigation was to identify the chromosomes of the wheatalien introgression line N124,derived from the hybridization between Triticum aestivum with Aegilops kotschyi,and characterize the effects on quality-related traits.Fluorescence in situ hybridization karyotypes showed that N124 is a disomic 1U^(k)(1A)substitution line.Sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE)and reversedphase high-performance liquid chromatography verified N124 expressed two HMW-GSs of the Ae.kotschyi parent.PacBio RNA sequencing and phylogenetic analysis confirmed that the two HMW-GSs were U^(k)x and U^(k)y.Compared to the wheat parent,the substitution line had no obvious agronomic defects except fewer grains per spike but improved several major quality parameters.It can be served as a donor or bridge material for wheat quality improvement.

State of Local Populations of Aegilops triuncalis L. in Uzbekistan

The genus Aegilops L. is considered one of the important representatives of the wild relative of cultivated plants. The article presents the place of Aegilops triuncialis L. in plant communities and the status of populations in the flora of Uzbekistan. The research was carried out in various botanical and geographical regions of Uzbekistan during 2021-2023 years. During the research, the existing literature and geobotanical records, samples stored in the Institute of Botany (TASH) fund, and data on the GBIF international website were analyzed. Based on literary sources, more than 100 local points were recorded. The vitality structure of 11 cenopopulations was studied during field research. Various abiotic and biotic factors influencing the state of populations were analyzed. The main cenopopulations of the species were observed to spread in various grassy shrubland communities.

Characterization of High-Molecular-Weight Glutenin Subunits and Their Coding Genes from Aegilops umbellulata

The high-molecular-weight (HMW) glutenin subunits and their coding genes from Aegilops umbellulata Zhuk. (UU, 2n = 2x = 14) were characterized using SDS-PAGE analysis and molecular approaches. SDS-PAGE analysis showed that the 1Ux subunits from four different accessions possessed electrophoretic mobilities close to, or slower than, that displayed by the 1Dx2.2 subunit of common wheat. The electrophoretic mobilities of the 1Uy subunits were generally similar to those shown by the 1Dy subunits of common wheat. The complete open reading frames of the 1Ux and 1Uy genes were amplified by PCR and subsequently cloned and sequenced. Amino acid sequence comparisons suggested that the primary structure of the 1Ux and 1Uy subunits were identical to that of published HMW glutenin subunits from related species, Phylogenetic analysis indicated that the HMW glutenin subunits of Ae. umbellulata were most closely related to those encoded by the D genome of Triticeae.

A Unique Aegilops tauschii Genotype Needless to Immature Embryo Culture in Cross with Wheat

Common or bread wheat ( Triticum aestivum L., AABBDD, 2n=42) originated ca. 8 000 years ago from hybridization of tetraploid wheat ( Triticum turgidum L., AABB, 2n=28) and diploid Aegilops tauschii Coss. (DD, 2n=14). An essential prerequisite for this evolutionary step is that the natural hybrids between tetraploid wheat and diploid Aegilops tauschii can produce relatively many filled seeds which germinated well. In this study, without special techniques, e.g. immature embryo culture, out of 22 Ae. tauschii accessions, the genotype AS60 produced relatively many filled seeds which germinated well. The seed germination percentages in the crosses of Ae. tauschii ×tetraploid wheat, tetraploid wheat× Ae. tauschii and Ae. tauschii ×common wheat were, respectively, 50.0%, 57.1% and 45.5%. It seems that Ae. tauschii accession AS60 has a unique genotype which facilitate hybrid seed development and viability, and which meets with the prerequisite for wheat evolutionary. Furthermore, the significance of this finding for common wheat improvement and evolution was discussed.

Development and Utilization of 1S^1 Chromosomearm-specific Molecular Markers of Aegilops longissima

Introducing the 1S^1 chromosome of Aegilops longissima into wheat genome can significantly improve wheat grain quality and contents of iron and zinc. Therefore, the development of molecular markers specific to 1S^1 chromosome of A. longissima is of important significance for breeding high-quality wheat with high contents of iron and zinc in grains. In this study, nine molecular markers specific to 1S^1 chromosome of A. longissima were developed, including two 1S^1S specific markers,six 1S^1L specific markers and one 1S^1 specific marker which was located on both short and long arms. The practicability of these molecular markers were verified using hybrid population as materials. The results showed that hybrid population could be effectively screened and identified, which indicated that the developed 1S^1 chromosome-specific molecular markers could be used for screening and identification of hybrid population and could be used in marker-assisted breeding of high-quality wheat with high contents of Fe and Zn in grains.

中国春phlb突变体与多倍体Aegilops杂种F_1回交植株(BC_1F_1)的细胞学研究

中国春 phlb突变体与 5个多倍体 Aegilops的杂种 F1 用普通小麦进行回交 ,并对回交一代 (BC1 F1 )的细胞学进行了研究。结果表明 ,BC1 F1 植株花粉母细胞最高染色体数 56条 ,最低 35条 ,一般情况下 phlb基因可以增加 BC1 F1 植株的染色体数 (不是所有组合 ) ,但不能增加染色体配对水平。杂种 F1 回交时有效雌配子最高染色体数在含有 phlb基因组合中高于不含 ph1 b基因的组合 ,但最低染色体数目相等 ,且含有 2 1条染色体雌配子最具有竞争力。同时也证明 ,回交的成功并不取决于杂种 F1 通过重建分裂 (restitution division)

Cytogenetical Analysis of Hybrid F1 from Common Wheat and Aegilops ventricosa × Aegilops cylindrica Amphidiploid

[Objective] The aim of this study is to investigate the chromosome pairing of F1 from Aegilops Ventricosa-Aegilops Cylindrica amphiploid × common wheat.[Method] Microsporogenesis and pollen development of Yannong15,SDAU18 and their hybrid F1 were observed cytologically by squash method.[Result] The results showed that microsporogenesis and pollen development of two parents including Yannong15 and SDAU18 were basically normal,and their seed setting was also basically normal.However,the microsporogenesis of their hybrid F1 was chaotic.Univalent and bivalent with high frequency of 10.11 and 18.29 per cell respectively occurred in meiotic MI（metphaseI） of PMC（pollen mother cell）.Nevertheless,only quite low frequency of multivalents occurred in meiotic PMC MI.The laggards at meiotic AI（anaphaseI） were 5 per cell on average.The number of micronucleoli in tetrad was 4.43 per cell averagely.The aborted pollen with different frequency occurred at every stage of hybrid F1 pollen development but mainly after single nucleus pollen stage.The fertile pollen rate of hybrid F1 was only 31% at 3-nucleated stage.[Conclusion] This study provides cytogenetics basis for further analysis and utilization of the amphiploid.

普通小麦—Aegilops crassa核质杂种的同工酶研究

对普通小麦—Aegilopscrassa核质杂种及其核亲本灌浆期旗叶过氧化物酶和酯酶同工酶进行了研究,结果表明:3个测试核亲本的过氧化物酶同工酶的谱带数和带有Aegilopscrassa细胞质的3个核质杂种的酶谱数不尽一致,但其中谱带1的酶活性均以弱势表达;核质杂种的酯酶同工酶与相应的核亲本比较酶带数目变化不明显,只是存在活性上的差异,这种差异在不同测试材料间也并未发现规律性的变化,表现了不同的核质杂种灌浆期旗叶过氧化物酶与酯酶同工酶的活性有所不同。说明Aegilopscrassa细胞质与普通小麦的细胞核结合产生的特异核质互作,在灌浆期旗叶的有关同工酶上也有所体现。

Production of aneuhaploid and euhaploid sporocytes by meiotic restitution in fertile hybrids between durum wheat Langdon chromosome substitution lines and Aegilops tauschii

Fertile F1 hybrids were obtained between durum wheat （Triticum durum Desf.） Langdon （LDN） and its 10 disomic substitution （LDN DS） lines with Aegilops tauschii accession AS60 without embryo rescue. Selfed seedset rates for hybrids of LDN with AS60 were 36.87% and 49.45% in 2005 and 2006, respectively. Similar or higher selfed seedset rates were observed in the hybrids of 1D （1A）, 1D （1B）, 3D （3A）, 4D （4B）, 7D （7A）, and 2D （2B） with AS60, while lower in hybrids of 3D （3B） ＋ 3BL, 5D （5A） ＋ 5AL, 5D （5B） ＋ 5B and 6D （6B） ＋ 6BS with AS60 compared with the hybrids of LDN with AS60. Observation of male gametogenesis showed that meiotic restitution, both first-division restitution （FDR） and single-division meiosis （SDM） resulted in the formation of functional unreduced gametes, which in turn produced seeds. Both euhaploid and aneuhaploid gametes were produced in F1 hybrids. This suggested a strategy to simultaneously transfer and locate major genes from the ancestral species T. turgidum or Ae. tauschii. Moreover, there was no significant difference in the aneuhaploid rates between the F1 hybrids of LDN and LDN DS lines with AS60, suggesting that meiotic pairing between the two D chromosomes in the hybrids of LDN DS lines with AS60 did not promote the formation of aneuhaploid gametes.

Tolerant Mechanism and Chromosome Location of Gene Controlling Sprouting Tolerance in Aegilops Tauschii Cosson

An artificial amphiploid RSP (2n = 42, AABBDD) between tetraploid landrace Ailanmai (Triticum turgidum L., 2n= 28, AABB) and Aegllops tauschii (DD, 2n = 14) expressed high tolerance to preharvest sprouting which derived from Ae. tauschii. Tolerance to preharvest sprouting of RSP was examined by four ways in six varying periods after anthesis. The germination percentages of preharvest intact spikes were only 6.06% in its high peak period of germination. Its tolerance was mainly decided by the seed dormancy. It was showed that the tolerance to sprouting in ' RSP' derived from Ae. tauschii was inherited as a recessive trait which was controlled by one gene, located on chromosome 2D.

Association analysis of grain traits with SSR markers between Aegilops tauschii and hexaploid wheat(Triticum aestivum L.)

Seven important grain traits, including grain length（GL）, grain width（GW）, grain perimeter（GP）, grain area（GA）, grain length/width ratio（GLW）, roundness（GR）, and thousand-grain weight（TGW）, were analyzed using a set of 139 simple sequence repeat（SSR） markers in 130 hexaploid wheat varieties and 193 Aegilops tauschii accessions worldwide. In total, 1 612 alleles in Ae. tauschii and 1 360 alleles in hexaploid wheat（Triticum aestivum L.） were detected throughout the D genome. 197 marker-trait associations in Ae. tauschii were identified with 58 different SSR loci in 3 environments, and the average phenotypic variation value（R2） ranged from 0.68 to 15.12%. In contrast, 208 marker-trait associations were identified in wheat with 66 different SSR markers in 4 environments and the average phenotypic R2 ranged from 0.90 to 19.92%. Further analysis indicated that there are 6 common SSR loci present in both Ae. tauschii and hexaploid wheat, which are significantly associated with the 5 investigated grain traits（i.e., GA, GP, GR, GL, and TGW） and in total, 16 alleles derived from the 6 aforementioned SSR loci were shared by Ae. tauschii and hexaploid wheat. These preliminary data suggest the existence of common alleles may explain the evolutionary process and the selection between Ae. tauschii and hexaploid wheat. Furthermore, the genetic differentiation of grain shape and thousand-grain weight were observed in the evolutionary developmental process from Ae. tauschii to hexaploid wheat.

Genomewide association study of Aegilops tauschii traits under seedling-stage cadmium stress

Aegilops tauschii Ais a wild relative of common wheat(Triticum aestivum) and acts as an important resource of elite genes including genes for resistance to biotic and abiotic stresses. To improve the cadmium(Cd) tolerance of wheat varieties using A. tauschii resources, we investigated the genetic variation of biomass-based Cd tolerance in 235 A. tauschii accessions treated with 0(control) and100 μmol L-1CdC l2(as Cd stress). Simultaneously, we performed a genomewide association study(GWAS) using a single-nucleotide polymorphism chip containing 7185 markers. Six markers were found to be significantly associated with Cd tolerance by a general linear model and a mixed linear model. These markers were close to several candidate/flanking genes associated with Cd tolerance according to results in public databases, including pdil5-1, Acc-1, DME-5A,TaA P2-D, TaA P2-B, Vrn-B1, and FtsH-like protein gene. The A. tauschii accessions were classified as high, moderate, and low Cd-tolerant according to a secondary index, the synthetic index(SI), in proportions of 9%, 57%, and 34%, respectively. By the average SI, accessions from Afghanistan,Turkey, Azerbaijan, and Iran showed relatively high Cd tolerance.

Comparing two approaches for introgression of germplasm from Aegilops tauschii into common wheat

Allelic diversity in the wild grass Aegilops tauschii is vastly greater than that in the D genome of common wheat(Triticum aestivum), of which Ae. tauschii is the source. Since the 1980 s,there have been numerous efforts to harness a much larger share of Ae. tauschii^ extensive and highly variable gene pool for wheat improvement. Those efforts have followed two distinct approaches: production of amphiploids, known as "synthetic hexaploids," between T. turgidum and Ae. tauschii,and direct hybridization between 丁. aestiuum and Ae. tauschii;both approaches then involve backcrossing to 丁. aestiuum. Both synthetic hexaploid production and direct hybridization have led to the transfer of numerous new genes into common wheat that confer improvements in many traits. This work has led to release of improved cultivars in China, the United States, and many other countries. Each approach to D-genome improvement has advantages and disadvantages. For example, production of synthetic hexaploids can incorporate useful germplasm from both T. turgidum and Ae.tauschii, thereby enhancing the A, B, and D genomes; on the other hand, direct hybridization rapidly restores the recurrent parent's A and B genomes and avoids incorporation of genes with adverse effects on threshability, hybrid necrosis, vernalization response, milling and baking quality, and other traits, which are often transferred when T. turgidum is used as a parent. Choice of method will depend in part on the type of wheat being developed and the target environment. However, more extensive use of the so-far underexploited direct hybridization approach is especially warranted.

Molecular mapping of the hybrid necrosis gene NetJingY176 in Aegilops tauschii using microsatellite markers

The rich genetic variation preserved in collections of Aegilops tauschii can be readily exploited to improve common wheat using synthetic hexaploid wheat lines. However,hybrid necrosis, which is characterized by progressive death of leaves or plants, has been observed in certain interspecific crosses between tetraploid wheat and Ae. tauschii. The aim of this study was to construct a fine genetic map of a gene(temporarily named Net Jing Y176)conferring hybrid necrosis in Ae. tauschii accession Jing Y176. A triploid F1 population derived from distant hybridization between Ae. tauschii and tetraploid wheat was used to map the gene with microsatellite markers. The newly developed markers Xsdau K539 and Xsdau K561 co-segregated with Net Jing Y176 on chromosome arm 2DS. The tightly linked markers developed in this study were used to genotype 91 Ae. tauschii accessions. The marker genotype analysis suggested that 49.45% of the Ae. tauschii accessions carry Net Jing Y176. Interestingly, hybrid necrosis genotypes tended to appear more commonly in Ae. tauschii ssp. tauschii than in Ae. tauschii ssp. strangulata.

Characterization of a Triticum aestivum-Aegilops germplasm line presenting reduced plant height and early maturation

Plant height plays an important role in the potential and stability of crop yields and represents one of the most important agronomic traits of wheat. Although more than 30 dwarfing genes have been identified in wheat, only a few are used in wheat breeding, which has narrowed the genetic basis of newly developed varieties. Therefore, continually identifying new dwarfing genes is required to produce improved wheat cultivars. TA001 is a new germplasm line marked by reduced plant height and early maturation, and it was derived from a hybridization between the common wheat Yannong 15 and the Aegilops ventricosa × Aegilops cylindrica amphiploid SDAU18. In this study, cytological observations, agronomic trait examinations, genomic in situ hybridization(GISH), multicolor genomic in situ hybridization(mc-GISH), multicolor fluorescence in situ hybridization(mc-FISH), SSR analysis and seed storage protein electrophoresis were combined to determine the cytological stability, main agronomic traits, chromosomal constituents and seed storage protein subunits of TA001. Twenty-one bivalents were observed in most of the pollen mother cells at metaphase I(PMCs MI) in TA001, which housed 42 chromosomes, and the chromosomes in most pollen mother cells at anaphase I(PMCs AI)displayed 21/21 segregation. Twenty bivalents plus two univalents were simultaneously observed in most of the PMCs MI of the hybrid F_1 between TA001 and Yannong 15. TA001 possessed all chromosomes from genomes A, B and D except for chromosome 7B, which was replaced by one pair of N-genome chromosomes from Aegilops ventricosa. Several pairs of chromosomes in TA001 exhibited different FISH patterns from the equivalent chromosomes in Yannong 15. TA001 housed alien genetic materials from Aegilops ventricosa and Aegilops cylindrica and possessed new glutenin and gliadin subunits specific to SDAU18, as revealed by molecular marker analysis and protein electrophoresis respectively.

Genome-wide characterization of early response genes to abscisic acid coordinating multiple pathways in Aegilops tauschii

The diploid wild goat grass Aegilops tauschii(Ae. tauschii, 2 n = 14;DD), as the D-sub genome of common wheat, provides rich germplasm resources for many aspects of wheat breeding. Abscisic acid(ABA) is an essential phytohormone that plays a pivotal role in plant adaptation to abiotic stresses. However,the gene regulation network of Ae. tauschii in response to ABA stress remains unclear. Here, we conducted a time-course strand-specific RNA-sequencing study to globally profile the transcriptome that responded to ABA treatment in Ae. tauschii. We identified 4818 differentially expressed transcription units/genes with time-point-specific induction/repression patterns. Using functional annotation, one-to-one ortholog and comparative transcriptome profiling analyses, we identified 319 ABA-responsive Ae. tauschii orthologs that were also induced/repressed under ABA treatment in hexaploid wheat. On the quantitative trait loci(QTL) used in wheat marker-assisted breeding, we found that the ABA-responsive expression patterns of eight Ae. tauschii orthologs were associated with drought stress tolerance, flowering process and/or grain quality. Of them, the ABA-responsive gene encoding sucrose:sucrose 1-fructosyltransferase in fructan and glucose metabolism pathways showed the most significant association with wheat drought tolerance. The characterization of ABA early-responsive genes in this study provides valuable information for exploring the molecular functions of the regulatory genes and will assist in wheat breeding.

Characterization of WAP2 gene in Aegilops tauschii and comparison with homoeologous loci in wheat

The Q/q gene, also known as WAP2, is an important gene for wheat domestication and is a member of the AP2 （APETALA2） class of transcription factors. In the present study, we first isolated the WRAP2 allele （where the superscript ＂t＂ refers to the speciese source, in this case ＂tauschii＂） on chromosome 5D from Aegilops tauschii Coss., the D-genome donor species of common wheat. We found that WRAP2 and the AP2 gene from Arabidopsis share a central core of the AP2 polypeptide, a highly basic 10-amino acid domain, and an AASSGF box, although there are many differences in the 37-amino acid serine-rich acidic domain and the remaining regions. In addition, WRAP2 was highly homologous to the homoeologous loci on 5A and 5B of wheat at both the nucleotide and amino acid level. However, there were some variations that are probably related to gene function. In the first AP2 domain, the amino acids VYL on the 5D and 5A loci were replaced with LLR on 5B. In the 37-amino acid serine-rich acidic domain, WRAP2 on 5D had an extra amino acid insertion. There was also a variation at the 329 amino acid position, which is thought to be related to the appearance of free-threshing wheat. At this position, the amino acid is isoleucine on 5A for the Q allele and valine for the q allele, whereas the amino acid is leucine on 5D and 5B. Furthermore, a Stowaway miniature terminal inverted repeat element （MITE） insertion was present in the ninth intron of WAP2 on 5B of all common wheats and partial tetraploid Triticum turgidum wheats. These results provide new clues for studies into the evolutionary biology of WAP2 and the origin of common wheat.