Project description:The centromeric histone H3 (CENH3) is of great importance in centromere identification identity, chromosome mobilization during cell division and thus genome stability. The imbalance of CENH3 loading rate or dosage on parental centromeres often leads to uniparental chromosome elimination in the offspring. A body of studies on the function of CENH3 in genome stability have been reported in Arabidopsis, cotton, and many other monocots, but not in soybean (Glycine max), an important dicot crop. In our study, we identified the a single-copy functional CENH3 in soybean and found its role in genome stability and parent-of-origin effect caused by a conserved glycine site and parental genetic background. This study identified the functional GmCENH3 and would shed light on the future development of CENH3-based haploid induction system and centromere biology in soybean.
Project description:Despite the essentiality for faithful chromosome segregation, centromere architectures are diverse among eukaryotes and embody two main configurations: mono- and holocentromeres, referring respectively to localized or unrestricted distribution of centromeric activity. Of the two, some holocentromeres offer the curious condition of having arisen independently in multiple insects, most of which have lost the otherwise essential centromere-specifying factor CenH3 (first described as CENP-A in humans). The loss of CenH3 raises intuitive questions about how holocentromeres are organized and regulated in CenH3-lacking insects. Here, we report the first chromatin-level description of CenH3-deficient holocentromeres by leveraging recently-identified centromere components and genomics approaches to map and characterize the holocentromeres of the silk moth Bombyx mori, a representative lepidopteran insect lacking CenH3. This uncovered a robust correlation between the distribution of centromere sites and regions of low chromatin activity along B. mori chromosomes. Transcriptional perturbation experiments recapitulated the exclusion of B. mori centromeres from active chromatin. Based on reciprocal centromere occupancy patterns observed along differentially-expressed orthologous genes of Lepidoptera, we further found that holocentromere formation in a manner that is recessive to chromatin dynamics is evolutionarily conserved. Our results help us discuss the plasticity of centromeres in the context of a role for the chromosome-wide chromatin landscape in conferring centromere identity rather than the presence of CenH3. Given the co-occurrence of CenH3 loss and holocentricity in insects, we further propose that the evolutionary establishment of holocentromeres in insects was facilitated through the loss of a CenH3-specified centromere.
Project description:The centromere, as an essential element to control chromosome segregation, is epigenetically determined by CENH3-containing nucleosomes as a functional marker, therefore the accurate deposition of CENH3 is crucial to chromosome transmission. We characterized the deposition of CENH3 in maize by over-expression and mutational analysis. Our results revealed that over-expressing CENH3 in callus is lethal while over-expressing GFP-CENH3 and CENH3-YFP in callus and plants is not and can be partly deposited normally. Different mutations of GFP-CENH3 demonstrated that CENH3-Thr4 in the N terminus was needed for the deposition as a positive phosphorylation site and the last five amino acids in the C terminus are necessary for deposition. The C terminal tail of CENH3 is confirmed to be responsible for the interaction of CENH3 and histone H4, which indicates that CENH3 maintains deposition in centromeres via interacting with H4 to form stable nucleosomes. For GFP-CENH3 and CENH3-YFP, the fused tags at the termini probably affect the structure of CENH3 and reduce its interaction with other proteins, which in turn could decrease proper deposition. Taken together, multiple amino acids or motifs were shown to play essential roles in CENH3 deposition, which is suggested to be affected by numerous factors in maize.
Project description:We report the binding profile of A. thaliana CENH3, L. oleraceum CENH3 and Z. mays CENH3 in the genetic background of A. thaliana Col ecotype. The L. oleraceum CENH3 and Z. mays CENH3 ChIP was performed in a cenh3 homozygous mutant background expressing CENH3 homologs as transgenes.
Project description:Submergence is a major constraint for soybean production worldwide and transient inundation after seeding causes serious loss of soybean productivity. To characterize genome-scale adjustment of gene expression to submergence and reoxygenation, whole transcriptome analysis was conducted using Affymetrix Soybean Gene 1.0 ST Arrays.
Project description:Submergence is a major constraint for soybean production worldwide and transient inundation after seeding causes serious loss of soybean productivity. To characterize genome-scale adjustment of gene expression to submergence and reoxygenation, whole transcriptome analysis was conducted using Affymetrix Soybean Gene 1.0 ST Arrays. Aerial tissue of soybean which were treated with 1 d submergence, 5 d submergence, and 5 d submergence + 1 d reoxygenation were subjected to RNA extraction and hybridization on Affymetrix microarrays (Soybean Gene 1.0 ST arrays). Non-submerged were used as control. Two independent biological replicates were analyzed for each treatment.
Project description:Plant and animal centromeres comprise megabases of highly repeated satellite sequences, yet centromere function can be specified epigenetically on single-copy DNA by the presence of nucleosomes containing a centromere-specific variant of histone H3 (cenH3). We determined the positions of cenH3 nucleosomes in rice (Oryza sativa), which has centromeres composed of both the 155-bp CentO repeat and single-copy non-CentO sequences. We find that cenH3 nucleosomes protect 90-100 bp of DNA from micrococcal nuclease digestion, sufficient for only a single wrap of DNA around the cenH3 nucleosome core. cenH3 nucleosomes are translationally phased with 155-bp periodicity on CentO repeats, but not on non-CentO sequences. CentO repeats have a ~10-bp periodicity in WW dinucleotides and in micrococcal nuclease cleavage, providing evidence for rotational phasing of cenH3 nucleosomes on CentO, and suggesting that satellites evolve for translational and rotational stabilization of centromeric nucleosomes.
Project description:Plant and animal centromeres comprise megabases of highly repeated satellite sequences, yet centromere function can be specified epigenetically on single-copy DNA by the presence of nucleosomes containing a centromere-specific variant of histone H3 (cenH3). We determined the positions of cenH3 nucleosomes in rice (Oryza sativa), which has centromeres composed of both the 155-bp CentO repeat and single-copy non-CentO sequences. We find that cenH3 nucleosomes protect 90-100 bp of DNA from micrococcal nuclease digestion, sufficient for only a single wrap of DNA around the cenH3 nucleosome core. cenH3 nucleosomes are translationally phased with 155-bp periodicity on CentO repeats, but not on non-CentO sequences. CentO repeats have a ~10-bp periodicity in WW dinucleotides and in micrococcal nuclease cleavage, providing evidence for rotational phasing of cenH3 nucleosomes on CentO, and suggesting that satellites evolve for translational and rotational stabilization of centromeric nucleosomes. Examination of measured size of rice centromere nucleosome