Introgression of Powdery Mildew Resistance Gene Pm56 on Rye Chromosome Arm 6RS Into Wheat

Powdery mildew, caused by the fungus Blumeria graminis f. sp. tritici, represents a yield constraint in many parts of the world. Here, the introduction of a resistance gene carried by the cereal rye cv. Qinling chromosome 6R was transferred into wheat in the form of spontaneous balanced translocation induced in plants doubly monosomic for chromosomes 6R and 6A. The translocation, along with other structural variants, was detected using in situ hybridization and genetic markers. The differential disease response of plants harboring various fragments of 6R indicated that a powdery mildew resistance gene(s) was present on both arms of rye chromosome 6R. Based on karyotyping, the short arm gene, designated Pm56, was mapped to the subtelomere region of the arm. The Robertsonian translocation 6AL⋅6RS can be exploited by wheat breeders as a novel resistance resource

The abundance of homoeologue transcripts is disrupted by hybridization and is partially restored by genome doubling in synthetic hexaploid wheat

Dataset S7. List of nonadditively expressed genes in F1 hybrids derived from AS2255 × AS60. (XLSX 72 kb

An experimental study on imaging Burkitt's lymphoma cells by atomic force microscope

Burkitt's lymphoma (BL) is a highly aggressive malignant tumor with high morbidity rate in children. Patients have different responses to the same therapy due to the molecular heterogeneity. Detailed observation of the surface structure of BL cells to locate the specific receptors (CD20) on the cell surface and measure the binding force between the CD20s and their cognate ligands (Rituximab) may give people a further understanding to BL cell's intrinsic properties and provide complementary approaches for the next generation of drug research and development. In this paper, we give an experimental study on how to obtain the morphology images of the BL cells both in air and liquid with atomic force microscope (AFM).The detailed procedures such as sample preparation of BL cells, parameter setting of AFM and so on, are presented, and the experimental results illustrate that the morphology image of the BL cell can be obtained in air or liquid respectively by using AFM. ©2010 IEEE.Link_to_subscribed_fulltex

Fluorescence in situ hybridization karyotyping reveals the presence of two distinct genomes in the taxon Aegilops tauschii

Abstract Background Aegilops tauschii is the donor of the bread wheat D genome. Based on spike morphology, the taxon has conventionally been subdivided into ssp. tauschii and ssp. strangulata. The present study was intended to address the poor match between this whole plant morphology-based subdivision and genetic relationships inferred from genotyping by fluorescence in situ hybridization karyotyping a set of 31 Ae. tauschii accessions. Results The distribution of sites hybridizing to the two probes oligo-pTa-535 and (CTT)10 split the Ae. tauschii accessions into two clades, designated Dt and Ds, which corresponded perfectly with a previously assembled phylogeny based on marker genotype. The Dt cluster was populated exclusively by ssp. tauschii accessions, while the Ds cluster harbored both ssp. strangulata and morphologically intermediate accessions. As a result, it is proposed that Ae. tauschii ssp. tauschii is restricted to carriers of the Dt karyotype: their spikelets are regularly spaced along the rachis, at least in the central portion of their spike. Accessions classified as Ae. tauschii ssp. strangulata carry the Ds karyotype; their spikelets are irregularly spaced. Based on this criterion, forms formerly classified as ssp. tauschii var. meyeri have been re-designated ssp. strangulata var. meyeri. Conclusions According to the reworking of the taxon, the bread wheat D genome was most probably donated by ssp. strangulata var. meyeri. Chromosomal differentiation reveals intra-species taxon of Ae. tauschii. Ae. tauschii ssp. tauschii has more distant relationship with breed wheat than ssp. strangulata and can be used for breeding improving effectively

The karyotype of Aegilops geniculata and its use to identify both addition and substitution lines of wheat

Abstract Background The annual allotetraploid species Aegilops geniculata harbors a number of traits relevant for wheat improvement. An effective cytogenetic method has yet to be developed to distinguish between each of its 14 chromosomes. Results A fluorescence in situ hybridization (FISH) approach was adopted to describe the karyotype of Ae. geniculata. Each of its 14 chromosomes was unequivocally recognized using a cocktail of three probes, namely pTa-713, (AAC)5 and pTa71. FISH karyotyping was then used to detect and characterize selections from an Ae. geniculata × bread wheat wide cross of a chromosome 1Mg disomic addition line and three 4Mg(4B) substitution lines. The identity of the addition line was confirmed by the presence of Glu-M1, detected both using an SDS-PAGE separation of endosperm proteins and by applying a PCR assay directed at the Glu-M1 locus. The status of the substitution lines was validated by genotyping using a wheat single nucleotide polymorphism chip. Conclusion FISH karyotyping based on pTa-713, (AAC)5 and pTa71 will be useful for determining the contribution of Ae. geniculata to derivatives of an Ae. geniculata × wheat wide cross. SNP chip-based genotyping is effective for confirming the status of whole chromosome wheat/alien substitution lines

Anthocyanin composition and nutritional properties of a blue-grained wheat-Triticum boeoticum substitution line

Diploid wild einkorn wheat, Triticum boeoticum Boiss (AbAb, 2n = 2x = 14), provides a resource of blue aleurone layers for wheat breeding. The anthocyanin composition and nutritional quality of the blue-grained wheat-Triticum boeoticum introgression line Z18-1244 were compared with those of its T. boeoticum parent G52 and bread wheat parent Crocus. The results showed that the content of all four anthocyanins averaged 67.24 μg/g in the whole meal of the blue-grained wheat Z18-1244, which was slightly lower than that in G52 (72.31 μg/g) but significantly higher than that in Crocus. The total essential amino acid content in Z18-1244 was 48.03% higher than that in Crocus. Compared with Crocus, the protein nutritional quality of Z18-1244 was improved, including an SRC increased by 5.31% and an EAAI increased by 22.70%. The contents of zinc (Zn) and iron (Fe) in the mineral elements were 74.5 mg/kg and 109.7 mg/kg with increases of 39.34% and 109.65%, respectively. The nutritional quality of Z18-1244 has been considerably improved in comparison with its common wheat parent Crocus. Therefore, Z18-1244 could be used as a potential germplasm for wheat breeding to improve the nutritional value of wheat-based end-products

Transcriptomic analysis provides insight into the genetic regulation of shade avoidance in Aegilops tauschii

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

QTug.sau-3B Is a Major Quantitative Trait Locus for Wheat Hexaploidization

International audienceMeiotic nonreduction resulting in unreduced gametes is thought to be the predominant mechanism underlying allopolyploid formation in plants. Until now, however, its genetic base was largely unknown. The allohexaploid crop common wheat (Triticum aestivum L.), which originated from hybrids of T. turgidum L. with Aegilops tauschii Cosson, provides a model to address this issue. Our observations of meiosis in pollen mother cells from T. turgidumxAe. tauschii hybrids indicated that first division restitution, which exhibited prolonged cell division during meiosis I, was responsible for unreduced gamete formation. A major quantitative trait locus (QTL) for this trait, named QTug.sau-3B, was detected on chromosome 3B in two T. turgidumxAe. tauschii haploid populations. This QTL is situated between markers Xgwm285 and Xcfp1012 and covered a genetic distance of 1 cM in one population. QTug.sau-3B is a haploid-dependent QTL because it was not detected in doubled haploid populations. Comparative genome analysis indicated that this QTL was close to Ttam-3B, a collinear homolog of tam in wheat. Although the relationship between QTug.sau-3B and Ttam requires further study, high frequencies of unreduced gametes may be related to reduced expression of Ttam in wheat

High Transferability of Homoeolog-Specific Markers between Bread Wheat and Newly Synthesized Hexaploid Wheat Lines

<div><p>Bread wheat (<i>Triticum aestivum</i>, 2n = 6x = 42, AABBDD) has a complex allohexaploid genome, which makes it difficult to differentiate between the homoeologous sequences and assign them to the chromosome A, B, or D subgenomes. The chromosome-based draft genome sequence of the ‘Chinese Spring’ common wheat cultivar enables the large-scale development of polymerase chain reaction (PCR)-based markers specific for homoeologs. Based on high-confidence ‘Chinese Spring’ genes with known functions, we developed 183 putative homoeolog-specific markers for chromosomes 4B and 7B. These markers were used in PCR assays for the 4B and 7B nullisomes and their euploid synthetic hexaploid wheat (SHW) line that was newly generated from a hybridization between <i>Triticum turgidum</i> (AABB) and the wild diploid species <i>Aegilops tauschii</i> (DD). Up to 64% of the markers for chromosomes 4B or 7B in the SHW background were confirmed to be homoeolog-specific. Thus, these markers were highly transferable between the ‘Chinese Spring’ bread wheat and SHW lines. Homoeolog-specific markers designed using genes with known functions may be useful for genetic investigations involving homoeologous chromosome tracking and homoeolog expression and interaction analyses.</p></div