Project description:GRAS-Di marker system facilitates high-density genetic map construction and QTL identifications in recombinant inbred lines of wheat diploid progenitor Aegilops tauschii
Project description:Aegilops tauschii is the donor of the wheat D subgenome and an important genetic resource for wheat. The assembly of Ae. tauschii acc. AL8/78 reference genome sequence Aet v4.0 was therefore an important milestone for wheat biology and breeding. The combination of the > 4.2 Gb size of the Ae. tauschii genome and > 84% of recently evolved repeated sequences make sequencing this genome challenging. Here, we report further advances in the development of the Ae. tauschii acc. AL8/78 genome sequence. Two new genome-wide optical maps were constructed and employed in the revision of pseudomolecules and estimations of gap lengths. Gaps were closed with contigs of single-molecule Pacific Biosciences reads. The number of gaps in Aet v5.0 decreased by 38,899 compared to Aet v4.0. Transposable elements and protein-coding genes were reannotated. The number of high-confidence genes was reduced from 38,886 in Aet v4.0 to 32,980 in Aet v5.0. A nonredundant set of 478 biologically important genes including many of known function in wheat was manually annotated. Sixty-one microRNA precursor and 60 phasiRNA loci were discovered, annotated, and their expression was characterized. Also characterized was expression of other small RNAs, such as hc-siRNAs and tRFs. This upgraded genome sequence will facilitate the use of Ae. tauschii in wheat breeding and biological research. Aegilops tauschii is the donor of the wheat D subgenome and an important genetic resource for wheat. The assembly of Ae. tauschii acc. AL8/78 reference genome sequence Aet v4.0 was therefore an important milestone for wheat biology and breeding. The combination of the > 4.2 Gb size of the Ae. tauschii genome and > 84% of recently evolved repeated sequences make sequencing this genome challenging. Here, we report further advances in the development of the Ae. tauschii acc. AL8/78 genome sequence. Two new genome-wide optical maps were constructed and employed in the revision of pseudomolecules and estimations of gap lengths. Gaps were closed with contigs of single-molecule Pacific Biosciences reads. The number of gaps in Aet v5.0 decreased by 38,899 compared to Aet v4.0. Transposable elements and protein-coding genes were reannotated. The number of high-confidence genes was reduced from 38,886 in Aet v4.0 to 32,980 in Aet v5.0. A nonredundant set of 478 biologically important genes including many of known function in wheat was manually annotated. Sixty-one microRNA precursor and 60 phasiRNA loci were discovered, annotated, and their expression was characterized. Also characterized was expression of other small RNAs, such as hc-siRNAs and tRFs. This upgraded genome sequence will facilitate the use of Ae. tauschii in wheat breeding and biological research. Aegilops tauschii is the donor of the wheat D subgenome and an important genetic resource for wheat. The assembly of Ae. tauschii acc. AL8/78 reference genome sequence Aet v4.0 was therefore an important milestone for wheat biology and breeding. The combination of the > 4.2 Gb size of the Ae. tauschii genome and > 84% of recently evolved repeated sequences make sequencing this genome challenging. Here, we report further advances in the development of the Ae. tauschii acc. AL8/78 genome sequence. Two new genome-wide optical maps were constructed and employed in the revision of pseudomolecules and estimations of gap lengths. Gaps were closed with contigs of single-molecule Pacific Biosciences reads. The number of gaps in Aet v5.0 decreased by 38,899 compared to Aet v4.0. Transposable elements and protein-coding genes were reannotated. The number of high-confidence genes was reduced from 38,886 in Aet v4.0 to 32,980 in Aet v5.0. A nonredundant set of 478 biologically important genes including many of known function in wheat was manually annotated. Sixty-one microRNA precursor and 60 phasiRNA loci were discovered, annotated, and their expression was characterized. Also characterized was expression of other small RNAs, such as hc-siRNAs and tRFs. This upgraded genome sequence will facilitate the use of Ae. tauschii in wheat breeding and biological research.
Project description:The huge size, the redundancy and the great repeated portion of the bread wheat genome [Triticum aestivum (L.)], placed it among the most difficult species to be sequenced and dissected at the genetic, structural and evolutionary levels. To overcome the limitations, a strategy based on the genome compartmentalization in individual chromosomes and the subsequent production of physical maps was established within the frame of the International Wheat Genome Sequence Consortium. A total of 95,812 BAC clones of short (5AS) and long (5AL) arm-specific BAC libraries, were fingerprinted and assembled into contigs by complementary analytical approaches based on FingerPrinted Contigs and Linear Topological Contig. Combined anchoring approaches based on PCR marker screening, microarray and BlastN searches, applied to interlinked genomic tools, that is genetic maps, deletion bin map, high-density neighbor map, BAC end sequences, genome zipper and chromosome survey sequences, allowed the development of a high quality physical map, with an anchored physical coverage of 75% for 5AS and 53% for 5AL, with high portions (64 and 48%, respectively) ordered along the chromosome. The gene distribution along the wheat chromosome 5A compared with the closest related genomes showed a pattern of syntenic blocks belonging to different chromosomes of Brachypodium, rice and sorghum and regions involving translocations and inversions. The physical map presented here is currently the most comprehensive map for 5A chromosome and represents an essential resource for fine genetic mapping and map-based cloning of agronomically relevant traits, and a reference for the 5A sequencing projects.
Project description:We have employed whole genome microarray expression profiling as a discovery platform to identify genes to alter the transcript accumulation levels in grass-clump dwarf lines, which are synthetic hexaploid lines from triploid hybrids crossed between tetraploid wheat (Triticum turgidum ssp. durum cv. Langdon or T. turgidum ssp. carthlicum) and diploid wheat progenitor Aegilops tauschii (KU2025). No up-regulation of defense-related genes was observed under the normal temperature, and down-regulation of wheat APETALA1-like MADS-box genes, considered to act as flowering promoters, was found in the grass-clump dwarf lines. Together with small RNA sequencing analysis of the grass-clump dwarf line, unusual expression of the miR156/SPLs module could explain the grass-clump dwarf phenotype.
Project description:The huge size, the redundancy and the great repeated portion of the bread wheat genome [Triticum aestivum (L.)], placed it among the most difficult species to be sequenced and dissected at the genetic, structural and evolutionary levels. To overcome the limitations, a strategy based on the genome compartmentalization in individual chromosomes and the subsequent production of physical maps was established within the frame of the International Wheat Genome Sequence Consortium. A total of 95,812 BAC clones of short (5AS) and long (5AL) arm-specific BAC libraries, were fingerprinted and assembled into contigs by complementary analytical approaches based on FingerPrinted Contigs and Linear Topological Contig. Combined anchoring approaches based on PCR marker screening, microarray and BlastN searches, applied to interlinked genomic tools, that is genetic maps, deletion bin map, high-density neighbor map, BAC end sequences, genome zipper and chromosome survey sequences, allowed the development of a high quality physical map, with an anchored physical coverage of 75% for 5AS and 53% for 5AL, with high portions (64 and 48%, respectively) ordered along the chromosome. The gene distribution along the wheat chromosome 5A compared with the closest related genomes showed a pattern of syntenic blocks belonging to different chromosomes of Brachypodium, rice and sorghum and regions involving translocations and inversions. The physical map presented here is currently the most comprehensive map for 5A chromosome and represents an essential resource for fine genetic mapping and map-based cloning of agronomically relevant traits, and a reference for the 5A sequencing projects. 55 DNA pools of short arm of chromsome 5A and 63 DNA pools of long arm of 5A. The DNAs derive from BAC clones of the Minimal Tiling Paths produced by physical assemly of BAC fingerprints.
Project description:We have employed whole genome microarray expression profiling as a discovery platform to identify genes to alter the transcript accumulation levels in hybrid necrosis-showing plants, which are triploid hybrids crossed between tetraploid wheat and diploid wheat progenitor Aegilops tauschii. Of the up-regulated genes, defense-related genes were most frequently found, whereas photosythesis-related genes down-regulated in the type I necrosis line. To validate the microarray data, RT-PCR and quantitative RT-PCR analyses for 22 selected genes were performed. Of the examined 15 up-regulated and 7 down-regulated genes, the expression pattern of only one down-regulated gene was inconsistent with the microarray data. Together with cytological analysis of the necrotic tissues, the microarray analysis strongly suggests that an autoimmune response might be triggered by intergenomic incompatibility between the AB and D genomes in type I necrosis, and that genetically programmed cell death could be regarded as a hypersensitive response-like cell death similar to that observed in Arabidopsis intraspecific and Nicotiana interspecific hybrids.