TADs and 3D Chromosome Structure

Jae Young Choi from New York University spoke at the Nanopore Community Meeting 2021 about “Unlocking the plant 3D genome architecture with Pore-C sequencing.” They spoke about how the genome is folded in a 3D conformation in the nucleus. There have also been many techniques to understand the folding. One such technique is Pore-C sequencing: a nanopore-based high-throughput 3D chromosome conformation capture technique. Pore-C uses the ligated products and provides amplification-free high resolution of repetitive regions. Choi’s group has been using Pore-C to assemble genomes of the plant Metrosideros from Hawaii. They used three flow cells on the GridION x5 to obtain a genome sequence. The were interested in Pore-C sequencing to better scaffold the genomes into 11 chromosomes of this genome. WIth four flow cells for Pore-C on the GridION they obtained this information. Next, they explored the 3D genome structure and transcription in rice (Oryza sativa) using three flow cells on the GridION X5 and a PromethION flow cell. Pore-C detects regions that are topologically associated: topologically associated domains (TADs). These regions are associated with enriched transcription, noted Choi, but they wanted to test this. They compared TADs from a Pore-C and a deep sequencing approach using short-read sequencing. The team was also interested in using Pore-C data to detect loops and enhancers. Choi and team used Pore-C to assemble genomes and learn about plant genome assembly and structure/function. It seems that Pore-C has several advantages: longer reads, less sequencing reads needed to determine contacts, and the opportunity to use DNA modification data to learn more about chromosome structure and function.

agricultural rice field near coconut palm tree on farmland
How can Pore-C be used to detect biologically-relevant chromosome contacts? Photo by Maria Orlova on Pexels.com