Search

Spikelet number and grain number per spike are two crucial and correlated traits for grain yield in wheat. Photoperiod-1(Ppd-1) is a key regulator of inflorescence architecture and spikelet formation in wheat. In this study, near-isogenic lines derived from the cross of a synthetic hexaploid wheat and commercial cultivars generated by double top-cross and two-phase selection were evaluated for the number of days to heading and other agronomic traits. The results showed that heading time segregation was conferred by a single incomplete dominant gene PPD-D1, and the 2 kb insertion in the promoter region was responsible for the delay in heading. Meanwhile, slightly delayed heading plants and later heading plants obviously have advantages in grain number and spikelet number of the main spike compared with early heading plants. Utilization of PPD-D1 photoperiod sensitivity phenotype as a potential means to increase wheat yield potential.

Low molecular weight glutenin subunits (LWM-GSs) play a crucial role in determining wheat flour processing quality. In this work, 35 novel LMW-GS genes (32 active and three pseudogenes) from three Aegilops umbellulata (2n = 2x = 14, UU) accessions were amplified by allelic-specific PCR. We found that all LMW-GS genes had the same primary structure shared by other known LMW-GSs. Thirty-two active genes encode 31 typical LMW-m-type subunits. The MZ424050 possessed nine cysteine residues with an extra cysteine residue located in the last amino acid residue of the conserved C-terminal III, which could benefit the formation of larger glutenin polymers, and therefore may have positive effects on dough properties. We have found extensive variations which were mainly resulted from single-nucleotide polymorphisms (SNPs) and insertions and deletions (InDels) among the LMW-GS genes in Ae. umbellulata. Our results demonstrated that Ae. umbellulata is an important source of LMW-GS variants and the potential value of the novel LMW-GS alleles for wheat quality improvement.

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is one of the most destructive diseases in wheat production. Pyramiding of adult-plant resistance (APR) genes is a promising strategy to increase durability of resistance. The stripe rust resistance (R) genes Yr18, Yr28, and Yr36 encode different protein families which confer partial resistance to a broad array of P. striiformis f. sp. tritici races. Here, we developed BC3F5 wheat lines representing all possible combinations of Yr18, Yr28, and Yr36 in a genetic background of the highly P. striiformis f. sp. tritici-susceptible wheat line SY95-71 that is widely used in stripe rust analysis. These lines enabled us to accurately evaluate these genes singly and in combination in a common genetic background. The adult plant resistance experiments were analyzed in the field, where stripe rust epidemics occurred frequently. The field results indicated that these partial R genes act additively in enhancing the levels of resistance, and a minimum of two-gene combinations can generate adequate stripe rust resistance. The Yr28 + Yr36 and Yr18 + Yr28 + Yr36 combinations also showed adequate resistance at the seedling stage, implying that APR gene pyramiding can achieve all-stage resistance. Meanwhile, the three genes were simultaneously introduced into elite wheat lines through gene-based marker selection. Elite lines exhibited strong all-stage resistance to stripe rust. This work provides valuable insights and resources for developing durable P. striiformis f. sp. tritici-resistant varieties and for elucidating the regulation mechanism of partial R gene pyramiding.

Triticum boeoticum (2n = 2x = 14, AbAb) is an important relative of wheat. This species tolerates many different types of environmental stresses, including drought, salt, and pathogenic infection, and is lower in dietary fiber and higher in antioxidants, protein (15 to 18%), lipids, and trace elements than common wheat. However, the gene transfer rate from this species to common wheat is low, and few species-specific molecular markers are available. In this study, the wheat-T. boeoticum substitution line Z1889, derived from a cross between the common wheat cultivar Crocus and T. boeoticum line G52, was identified using multicolor fluorescence in situ hybridization, multicolor genomic in situ hybridization, and a 55K single-nucleotide polymorphism array. Z1889 was revealed to be a 4Ab (4B) substitution line with a high degree of resistance to stripe rust pathogen strains prevalent in China. In addition, 22 4Ab chromosome-specific molecular markers and 11 T. boeoticum genome-specific molecular markers were developed from 1,145 4Ab chromosome-specific fragments by comparing the sequences generated by specific-length amplified fragment sequencing, with an efficiency of up to 55.0%. Furthermore, the specificity of these markers was verified in four species containing the Ab genome. These markers not only can be used for the detection of the 4Ab chromosome but also provide a basis for molecular marker-assisted, selection-based breeding in wheat.

Genetic diversity is an important resource to improve new wheat cultivars in the breeding program. In this study, fluorescence in situ hybridization (FISH) and genotyping by sequencing (GBS) were used to evaluate the genetic diversity and population structure of the timopheevii group (AtAtGG, 2n = 4x = 28) including 15 Triticum timopheevii Zhuk. accessions and 35 Triticum araraticum Jakubz. accessions. FISH analysis showed that there were 14 and 19 FISH signal variations in the At and G genome of T. araraticum, respectively. But there were only two signal variations in the G genome of T. timopheevii. In this study, 190,402 SNP markers were obtained from GBS, in which the lowest and highest frequencies of SNPs were found in the G and At genomes, respectively. Genetic diversity analysis of the 50 accessions indicated that the mean GD and PIC were 0.30 and 0.26, with the ranges of 0.1–0.5 and 0.1–0.4, respectively. The highest and lowest numbers of SNPs identified on the chromosomes 4G and 2At were 7,748 and 17,527, respectively. Structure and cluster analyses divided 50 accessions into two subpopulations (POP1 and POP2). POP1 mainly consisted of most Triticum araraticum accessions, and POP2 comprised all accessions of Triticum timopheevii and one Triticum araraticum accession AS273. In addition, the genetic variance showed that genetic variation was greater within populations (97%) than between populations (3%). POP1 and POP2 had high levels of genetic diversity and POP1 showed higher genetic diversity. The POP1 (I = 0.53, He = 0.35, uh = 0.35) showed higher genetic diversity than POP2. The present results provided important information for the improvement of cultivated durum and hexaploid wheat production in future breeding programs of China and other countries.

Background and aims Wheat is the major nutrient source for numerous people. Aegilops tauschii Coss. (DD), the D genome donor of common wheat (BBAADD), exhibits abundant genetic variations in selenium and zinc concentrations. Ae. tauschii accession AS2407 exhibited prominent Se and Zn accumulation ability. The objectives of this study were to map Se and Zn accumulation-related quantitative trait loci (QTLs) and to identify candidate genes controlling Se and Zn accumulation in Ae. tauschii. Methods In this study, quantitative trait locus (QTL) mapping was carried out for selenium and zinc accumulation in the aerial parts of recombinant inbred lines (RILs) derived from two subspecies, AS2407 (Ae. tauschii. ssp. strangulate) and AS65 (Ae. tauschii. ssp. tauchii), and candidate genes were screened. Kompetitive allele-specific polymerase chain reaction (KASP) markers, which are closely linked to QTLs, were developed, and their distributions were detected in a natural population of Ae. tauschii. Results QTLs controlling selenium and zinc content were identified on chromosomes 1D and 2D, named QSe-1D and QZn-2D, respectively, which could explain 11.94% and 13.49% of the phenotypic variation, respectively. Five selenium-related candidate genes and three zinc-related candidate genes were screened. KASP markers (KASP_Chr1_22217614 and KASP_Chr2_57200260) were developed. QSe-1D and QZn-2D are the first mapped QTLs controlling selenium and zinc accumulation in the aerial part of Ae. tauschii. Conclusions These QTLs and KASP markers will be useful for quality improvement of wheat high nutrition and valuable for understanding the biological basis of Se and Zn intake in Ae. tauschii.

Triticum boeoticum (2n = 2x = 14, AbAb) contains beneficial traits for common wheat improvement. The discrimination of Ab-genome chromosomes from A-genome chromosomes is an important step in gene transfer from T. boeoticum to common wheat. In this study, fluorescence in situ hybridization (FISH) analysis using nine oligonucleotide probes revealed high divergence between chromosomes of the common wheat germplasm Crocus and T. boeoticum accession G52. The combination of Oligo-pTa535-HM and Oligo-pSc119.2-HM can differentiate Ab and A chromosomes within homologous groups 2, 4, 5, and 6; chromosomes 2Ab and 6Ab can be identified by using (ACT)7, (CTT)7, and (GAA)7. The probes Oligo-pTa713 and (ACT)7 can be utilized for the identification of chromosomes 1Ab and 3Ab, respectively. Probes (CAG)7 and (CAC)7 can be applied in the identification of 7Ab. Moreover, probe combinations consisting of Oligo-pTa535-HM and (AAC)7 with (ACT)7 or (CTT)7 and of Oligo-pTa535-HM and Oligo-pTa713 with (CAC)7 or (CTT)7 will help discriminate the Ab-genome chromosomes of T. boeoticum. These probes are being used as potential markers to select common wheat Crocus-T. boeoticum G52 alien chromosome lines. Moreover, FISH patterns are highly divergent between Ab- and A-genome chromosomes, indicating that obvious chromosome structural variations arose during wheat evolution.

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a destructive fungal disease with a significant economic impact. Aegilops tauschii, the D-genome progenitor of wheat (Triticum aestivum, AABBDD), offers valuable gene pool for Pst resistance. The Ae. tauschii gene YrAS2388 confers resistance to a wide range of Pst races and encodes a typical nucleotide oligomerization domain-like receptor (NLR). The functional YrAS2388R has duplicated 3′ untranslated regions (3′UTRs). In the present study, we have developed two gene-specific kompetitive allele specific PCR (KASP) markers for YrAS2388R by comparing multiple homoeologous and paralogous genomic sequences of YrAS2388 alleles from allopolyploid wheat genomes. KASP-E5 was developed based on SNP in the exon5 sequences of YrAS2388, which behaves as a co-dominant marker. KASP-E6′ was developed based on the 3′UTR sequences of YrAS2388, which behaves as a dominant marker. These markers were validated in different types of wheat populations and showed clear functional differentiation that was completely agreement with the gel based gene-specific marker for YrAS2388R. Our results indicate that KASP-E5 and KASP-E6′ are perfect diagnostic markers for YrAS2388R and would be useful for marker assisted selection in wheat resistance breeding.

Stem solidness is an important agronomic trait for increasing the ability of wheat to resist lodging. In this study, four new synthetic hexaploid wheat with solid stems were developed from natural chromosome doubling of F1 hybrids between a solid-stemmed durum wheat (Triticum turgidum ssp. durum, 2n = 4x = 28, AABB) and four Aegilops tauschii (2n = 2x = 14, DD) accessions. The solid expression of the second internode at the base of the stem was stable for two synthetic hexalpoid wheat Syn-SAU-117 and Syn-SAU-119 grown in both the greenhouse and field. The lodging resistance of four synthetic solid-stem wheats is stronger than that of CS, and Syn-SAU-116 has the strongest lodging resistance, followed by Syn-SAU-119. The paraffin sections of the second internode showed that four synthetic wheat lines had large outer diameters, well-developed mechanical tissues, large number of vascular bundles, and similar anatomical characteristics with solid-stemmed durum wheat. The chromosomal composition of four synthetic hexaploid wheat was identified by FISH (fluorescence in situ hybridization) using Oligo-pSc119.2-1 and Oligo-pTa535-1. At adult stage, all four synthetic hexaploid wheat showed high resistance to mixed physiological races of stripe rust pathogen (CYR31, CYR32, CYR33, CYR34). These synthetic hexaploid wheat lines provide new materials for the improvement of common wheat.

Introgressing one-eighth of synthetic hexaploid wheat genome through a double top-cross plus a two-phase selection is an effective strategy to develop high-yielding wheat varieties. The continued expansion of the world population and the likely onset of climate change combine to form a major crop breeding challenge. Genetic advances in most crop species to date have largely relied on recombination and reassortment within a relatively narrow gene pool. Here, we demonstrate an efficient wheat breeding strategy for improving yield potentials by introgression of multiple genomic regions of de novo synthesized wheat. The method relies on an initial double top-cross (DTC), in which one parent is synthetic hexaploid wheat (SHW), followed by a two-phase selection procedure. A genotypic analysis of three varieties (Shumai 580, Shumai 969 and Shumai 830) released from this program showed that each harbors a unique set of genomic regions inherited from the SHW parent. The first two varieties were generated from very small populations, whereas the third used a more conventional scale of selection since one of bread wheat parents was a pre-breeding material. The three varieties had remarkably enhanced yield potential compared to those developed by conventional breeding. A widely accepted consensus among crop breeders holds that introducing unadapted germplasm, such as landraces, as parents into a breeding program is a risky proposition, since the size of the breeding population required to overcome linkage drag becomes too daunting. However, the success of the proposed DTC strategy has demonstrated that novel variation harbored by SHWs can be accessed in a straightforward, effective manner. The strategy is in principle generalizable to any allopolyploid crop species where the identity of the progenitor species is known.

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most damaging diseases of wheat globally and resistance is the effectively control strategy. Triticum boeoticum Boiss (T. monococcum L. ssp. aegilopoides, 2n = 2x = 14, AbAb) accession G52 confers a high level of adult-plant resistance against a mixture of the Chinese prevalent Pst races. To transfer the resistance to common wheat, a cross was made between G52 and susceptible common wheat genotype Crocus. A highly resistant wheat-T. boeoticum introgression line Z15-1370 (F5 generation) with 42 chromosomes was selected cytologically and by testing with Pst races. In order to map the resistance gene(s), F1, F2, and F2:3 generations of the cross between Z15-1370 and stripe rust susceptible common wheat Mingxian169 were developed. Genetic analysis revealed that the resistance in Z15-1370 was controlled by a single recessive gene, temporarily designated YrZ15-1370. Using the bulked segregant RNA-Seq (BSR-Seq) analysis, YrZ15-1370 was mapped to chromosome 6AL and flanked by markers KASP1370-3 and KASP-1370-5 within a 4.3 cM genetic interval corresponding to 1.8 Mb physical region in the Chinese Spring genome, in which a number of disease resistance-related genes were annotated. YrZ15-1370 differed from previously Yr genes identified on chromosome 6A based on its position and/or origin. The YrZ15-1370 would be a valuable resource for wheat resistance improvement and the flanking markers developed here should be useful tools for marker-assisted selection (MAS) in breeding and further cloning the gene.

Wild relatives represent an important genetic pool for crop improvement. In wheat, a popular strategy for the introduction of alien genes is by manipulation of the Ph1 gene, to induce recombination between homoeologous chromosomes. However, the frequency of such homoeologous recombination is low and requires screening of large progeny samples. Consequently, the efficiency of selection of homoeologous recombinants is important. In this study, we developed two kompetitive allele-specific PCR (KASP) markers specific for chromosome arms 6VS of Haynaldia villosa L. and 6AS of wheat, Triticum aestivum L., one close to the terminal regions and the other near the centromeres. Of the 121 progeny from plants heterozygous for the 6VS·6AL translocation and homozygous for ph1b screened by the two KASP markers, three (2.5%) have shown an exchange of markers, and their recombinant nature was confirmed by in situ DNA hybridization. A recombinants chromosome with a small 6VS fragment carrying the powdery mildew resistance gene (Pm21) would be useful in wheat breeding. The two KASP markers tested here can be used for efficient detection of recombinants between 6AS and 6VS.

Before nineteenth century, biological science was restricted by the level of development and technical conditions. The classical taxonomy based on comparative morphology was the leading discipline of the development of biological science. The research method is based on the comparative morphological study of herbarium, with reference to geographical distribution and other collecting records to identify similarities and differences, thus to classify and identify species. Although using this shallow method can also reflect natural system relations to some extent, it is impossible to clarify complex problems between species by this strategy, which inevitably brings many wrong results.

Additional file 1 : Fig. S1 FISH karyotypes of the newly synthesized hexaploid wheat. (a) Euploid plant with 2n = 42. (b) M4B: plant lacking one copy of chromosome 4B (red arrow). (c) Tri4B: plant carrying an extra copy of chromosome 4B (red arrow). (d) SegT2A: plant harbouring a duplicated segment of the short arm of chromosome 2A (red arrow). (e) N7B + SegT2A, plant lacking both copies of chromosome 7B and harbouring a duplicated segment of the short arm of chromosome 2A (red arrow). Fig. S2 FISH- and GISH-based karyotyping used to validate the aneuploid status of the SegT2A material. (a) FISH karyotype of an SHW line carrying a wild-type copy of chromosome 2A; (b) FISH karyotype of an SHW line carrying the version of chromosome 2A (arrowed) shown to include a duplication of a part of its short arm. (c) GISH karyotype of an SHW line carrying SegT2A. The karyotype suggests that the copy of chromosome 2A contains additional sequences inherited from an A-subgenome chromosome. Labelling based on the probes Oligo-pSc119.2 (red) and Oligo-pTa-535 (green). Table S1 The effect of aneuploidy on leaf length and width. *, **: means differ from one another at P ≤ 0.05 and ≤ 0.01, respectively (statistical significance was determined using Student’s t test). Comparisons were made between euploid plants and the aneuploids M4B, Tri4B and SegT2A and between N7B + SegT2A and SegT2A. Table S2 RNA-Seq reads and their alignment with the CS wheat reference genome sequence v1.0. a Uniquely aligned reads designated according to the criteria suggested by Pfeifer et al. [42]. Table S3 GO analysis of DTGs mapped to chromosomes not involved in aneuploidy.

As mentioned above, as early as in 1833, Link found a wild plant similar to T. monococcum in the Balkans and Asia Minor. He named it as Crithodium aegilopoides Link. In 1854, Balansa found the same wild wheat in Mt. Sipylus, Syria, Iraq, and Iran in Asia Minor. They were merged into Triticum and changed to T. aegilopoides (Link) Bal. E. Boissier (1853) named the specimen collected from Boeotia Plain as T. boeoticum Boiss. In fact, they were the same species. T. aegilopoides (Link) Bal. was also the same name as T. aegilopoides Forssk. that was earlier published by Forsskal P. According to plant nomenclature rules, T. aegilopoides (Link) Bal. should be abandoned and T. boeoticum Boiss. should be the valid name of the wild wheat. In 1855, Kotschy discovered the wild barley Hordeum spontaneum in Mount Hermon, Palestine. Karnicke found that partial spikes in the specimen belonged to another wild wheat species that was named as T. dicoccoides Korn (1873). It also attracted the attention of agronomists because it was similar to the cultivated species T. dicoccon Schrank. Aaronsohn made a special investigation in 1904. At first, he did not find the wild wheat near Mt. Hermon. However, in 1906, he rediscovered the plant at 1900 m above sea level in Hermon and the Jordan Valley. In 1910, Cook discovered that this species was sporadically distributed in rock crevices on the slopes of Mount Anti-Lebanon in the limestone savanna eco-environment. Later, it was also discovered in Syria, Armenia, the Transcaucasus, and Western Iran. Compared to T. dicoccoides, the distribution of T. boeoticum was wider, including the Balkans, Asia Minor, Crimea, the Transcaucasus, Palestine, Syria, Iraq, and most parts of Iran, where the eco-geographic types vary somewhat. Reuter divided it into two species according to spikelets with one or two long awns. He designated the species with two long awns as T. thaoudar Reuter. However, Schiemann (1932) considered that it could only belong to a taxon class of subspecies.

In 1928, the Soviet botanist П. М. Жуковский published his works “A critical systematical survey of the species of the genus Aegilops” in Тридыпо Прикладной Бот Ген и Сел (18: 417–609). In this work, he acknowledged 20 species, two of which were newly published. He divided this genus into nine sections. The system was as follows

In the second half of the nineteenth century, many works on taxa and classifications below species were carried out on the genus Triticum. For instance, Alefeld (1866) used characteristics of spike and grain to classify varietas. Kornicke (1885) further developed and made a number of varietas names, some of which are still used by some people. They identified varietas using the characteristics such as spikes with awns or awnless, hairy or hairless glumes, spike color (white, red, black), and grain color (white, red). In the twentieth century, such artificial classification was adopted by Вавилов, Фляксбергр, Туманян, Якубцнер of the former Soviet union school and some scientists in other countries, for example Percival, making classification very complicated. In our opinion, over-complex classification is not necessary in scientific theory and useless in productive practice. The classification on the basis of simple phenotypic traits cannot effectively reflect the naturally phylogenetic relationships in many cases. However, in cultivated crops, cultivar that is developed by artificial selection on human economic purposes is a useful unit with economic significance. Correspondingly, in the natural environment, varietas formed by natural selection is the natural unit of evolutionary adaptation.

The investigation on the wild wheat in the past 100 years have found wild wheat including T. monococcum var. boeoticum, T. monococcum var. thaoudar, T. urartu, T. turgidum var. dicoccoides, and T. timopheevi var. araraticum. However, the wild type of common wheat has been not found yet. The wild T. monococcum is distributed in the Middle East and nearby regions, including Balkans, Turkey, Syria, Jordan, Lebanon, Palestine, northern Iraq, Northwestern Iran, Armenia, Azerbaijan, the Transcaucasia, the northern coast of the Black Sea, and southern coast of the Sea of Azov to the Crimean Peninsula. T. urartu is distributed in the mountains of Armenia, Israel, Syria, Palestine, northwest Iran, southeastern Turkey, and other Fertile Crescent areas. T. turgidum var. dicoccoides is distributed in the eastern coast of the Mediterranean Sea, namely northern Palestine, Lebanon, western and northwestern of Syria, southeastern Turkey, northeastern Iraq, and adjacent areas of northwestern Iran, Armenia, Azerbaijan, and Transcaucasia. T. timopheevi var. Araraticum is only distributed in Armenia, Azerbaijan, Naxcivan, and Iran. Apparently, these wild species had existed before humans began farming. The primitive humans selected wheat as a food resource, probably due to the relatively big grains with high quality. After the primitive humans knew how to cultivate, T. monococcum and T. turgidum were then cultivated and spread.

The artificial colchicine treatment or spontaneous chromosome doubling of interspecific/intergeneric hybrids can generate amphiploids that can set seeds. Using this strategy, many newly synthetic species or genus was produced. Some species, such as rye (Secale), Haynaldia, and Lophopyrum, are very easy to cross with wheat to produce hybrids even without special treatments such as embryo rescues. Generally, seedlings of intergeneric hybridization in Triticeae can be obtained by rescues of immature embryos at 14 days (sometimes 7 days) after cross-pollination. More distant hybridization such as wheat-maize can be also possible (Laurie and Bennett, 1986, 1987). Some successful examples of interspecific and intergeneric hybridization are shown in Table 11.1.

From the end of the nineteenth century to the beginning of the twentieth century, many problems in wheat taxonomy were gradually clarified. August Albert Heinrich Schulz (1913) made a great contribution to the natural system relation of Triticum. His research had made clear that Triticum includes three natural groups (reihe), i.e., Einkorn-reihe, Emmer-reihe, and Dinkel-reihe. Referring to the classification opinion of A. de Candolle’s based on structural morphological and adaptive traits, he classified the species of Triticum into the system in Table 4.1.

In the early twentieth century, the British botanist Percival J. and the Soviet botanist Н. И. Вавилов organized worldwide surveys and collections of wheat and conducted cultivation experiments, genetic, breeding, and taxonomic studies. Percival’s viewpoints of classification system were published in The wheat plant, a monograph. He ignored the scientific achievements including cytology at that time, also including his own observation and study, and subjectively classified Triticum into two species and eleven cultivation races. Percival (1921) said that “To these groups I have applied the term ‘race’ rather than the term ‘species’, although they might with equal justice be designated ‘cultivated species’, for the methods used in their grouping and delimitation are same as those adopted in the case of wild species.” He only admitted 2 wild wheat species, but combined the emmer with dinkel wheat and put 11 cultivated wheat under 2 species as cultivated races, namely

Stepping into the twenty-first century, researches on Triticum and its relative genera have passed three centuries. Many scientists from all over the world have been preoccupied with the classification and evolution, especially with the help of new genetic techniques in the twentieth century. The resulting great achievements offer the premise of the scientific management of germplasm and necessary theoretical knowledge for breeding utilization. Meanwhile, the following questions can be clarified, answered, or affirmed.

Triticum monococcumssp.monococcumhas useful traits for bread wheat improvement. The synthesis ofTriticum turgidum–T. monococcumamphiploids is an essential step for transferring genes fromT. monococcuminto bread wheat. In this study, 264 wide hybridization combinations were done by crossing 60T. turgidumlines belonging to five subspecies with 83T. monococcumaccessions. Without embryo rescue and hormone treatment, from the 10,810 florets pollinated, 1983 seeds were obtained, with a mean crossability of 18.34% (range 0–89.29%). Many hybrid seeds (90.73%, 923/1017) could germinate and produce plants. A total of 56 new amphiploids (AABBAmAm) were produced by colchicine treatment ofT. turgidum×T. monococcumF1hybrids. The chromosome constitution of amphiploids was characterized by fluorescencein situhybridization using oligonucleotides probes with different chromosome and sub-chromosome specificities. Sodium dodecyl sulphate polyacrylamide gel electrophoresis analysis indicated that theGlu-A1m-b,Glu-A1m-c,Glu-A1m-dandGlu-A1m-hproteins ofT. monococcumwere expressed in some amphiploids. Despite resistance reduction in several cases, 45 out of 56 amphiploids exhibited resistance to the current predominant Chinese stripe rust races at both the seedling and adult plant stage. These novel amphiploids provide new germplasm for the potential improvement of bread wheat quality and stripe rust resistance.

Diploid wild einkorn wheat, Triticum boeoticum Boiss (AbAb, 2n = 2x = 14), is a wheat-related species with a blue aleurone layer. In this study, six blue-grained wheat lines were developed from F8 progeny of crosses between common wheat and T. boeoticum. The chromosome constitutions of these lines were characterized by fluorescence in situ hybridization (FISH) using the oligonucleotide probes Oligo-pTa535-1, Oligo-pSc119.2-1, Oligo-pTa71-2, and (AAC)7. Multicolor FISH using Oligo-pTa535-1, Oligo-pSc119.2-1, and Oligo-pTa71-2 identified all 42 common wheat chromosomes, while Oligo-pTa535-1 and (AAC)7 discriminated the 14 chromosomes of T. boeoticum. FISH revealed that all six blue-grained lines were wheat-T. boeoticum 4Ab (4B) disomic substitution lines. The substitution lines were validated by genotyping using the wheat 55 K single nucleotide polymorphism (SNP) array containing 53,063 markers. These 4Ab (4B) substitution lines represent novel germplasm for blue-grained wheat breeding. The FISH probes and SNP markers used here can be applied in the development of blue-grained wheat-Triticum boeoticum translocation lines.

Background In contrast to most animal species, polyploid plant species are quite tolerant of aneuploidy. Here, the global transcriptome of four aneuploid derivatives of a synthetic hexaploid wheat line was acquired, with the goal of characterizing the relationship between gene copy number and transcript abundance. Results For most of the genes mapped to the chromosome involved in aneuploidy, the abundance of transcripts reflected the gene copy number. Aneuploidy had a greater effect on the strength of transcription of genes mapped to the chromosome present in a noneuploid dose than on that of genes mapped elsewhere in the genome. Overall, changing the copy number of one member of a homeologous set had little effect on the abundance of transcripts generated from the set of homeologs as a whole, consistent with the tolerance of aneuploidy exhibited by allopolyploids, whether in the form of a chromosomal deficit (monosomy) or chromosomal excess (trisomy). Conclusions Our findings shed new light on the genetic regulation of homeoallele transcription and contribute to a deeper understanding of allopolyploid genome evolution, with implications for the breeding of polyploid crops.

Triticum boeoticum (2n = 2x = 14, A

Six new amphiploids, Triticum kiharae Dorof. et Migusch. (2n = 6x = 42, AtAtGGDD), are described in this study. They were developed by the chromosome doubling of F1 hybrid crosses between Triticum timopheevii Zhuk. (AtAtGG) with high resistance to stripe rust and Aegilops tauschii Cosson (DD) by colchicine treatment. These amphiploids showed a high level of fertility of 68–80% and exhibited relatively normal chromosome pairing in meiotic metaphase I. Individual chromosomes of T. kiharae could be identified by multicolor fluorescence in situ hybridization using the combination of oligonucleotides probes Oligo-pSc119.2-1, Oligo-pTa535-1, and Oligo-pTa71-2. T. kiharae exhibited high resistance to predominant stripe rust races CYR34, CYR31, CYR32, CYR33, and SY11-4 both during the seedling and adult stages. However, high molecular weight glutenin subunits from Ae. tauschii parents were only partially expressed in the T. kiharae background. These T. kiharae lines provide novel materials to widen the genetic diversity of the common wheat gene pool.