Project description:Centromeres are chromosomal regions that serve as platforms for kinetochore assembly and spindle attachments, ensuring accurate chromosome segregation during cell division. Despite functional conservation, centromeric sequences are diverse and usually repetitive across species, making them challenging to assemble and identify. Here, we describe centromeres in the model oomycete Phytophthora sojae by combining long-read sequencing-based genome assembly and chromatin immunoprecipitation for the centromeric histone CENP-A followed by high-throughput sequencing (ChIP-seq). P. sojae centromeres cluster at a single focus in the nucleus at different life stages and during nuclear division. We report a highly contiguous genome assembly of the P. sojae reference strain, which enabled identification of 15 highly enriched CENP-A binding regions as putative centromeres. By focusing on 10 intact regions, we demonstrate that centromeres in P. sojae are regional, spanning 211 to 356 kb. Most of these regions are transposon-rich, poorly transcribed, and lack the euchromatin mark H3K4me2 but are embedded within regions with the heterochromatin marks H3K9me3 and H3K27me3.
Project description:We report the H3K27me3 profile on Avr1b locus in two Phytophthora sojae strains P6497 and pssu(z)12 mutant. Nuclei of Phytophthora sojae P6497 and pssu(z)12 mutant T34 (lost 561bp by CRISPR/Cas9) mycelium (3-days old) was extracted and digested to 200-400bp using micrococcal nuclease (MNase: NEB M0247S). The antibody Millipore 07-449 was used to immunoprecipitation. We find significant accumulation of H3K27me3 at Avr1b locus in Avr1b silencing strain P6497 and clear H3K27me3 depletion at Avr1b locus in Avr1b unsilenced strain pssu(z)12 mutant T34.
