Identifying crossover locations from leaves of Arabidopsis thaliana Col x Ler F1 plants (WT and recq4) using Nanopore-seq and COmapper
We sequenced DNA from the leaves of  ten Col x Ler F1 hybrid plants (WT and recq4) using Nanopore long-read sequencing and identified crossover sites with COmapper. These data were used as a negative control for COmapper, as no crossover sites were expected to be detected. For nanopore sequencing of gDNA from leaves, leaves from 10 5-week-old plants were ground in liquid nitrogen using a mortar and pestle. The ground tissue was resuspended in four volumes of CTAB buffer (1% [w/v] CTAB, 50 mM Tris-HCl pH 8.0, 0.7 M NaCl, 10 mM EDTA) and incubated at 65°C for 30 min. Following chloroform extraction, isopropanol precipitation and removal of RNAs as above, the gDNA pellet was resuspended in 150 µl TE (10 mM Tris-HCl pH 8.0, 0.1 mM EDTA) buffer and gDNA was quantified using a Qubit dsDNA Broad Range assay kit (Thermo Fisher, Q32853). Nine micrograms of gDNA from pollen or seedlings was used to construct a nanopore long-read sequencing library using a Ligation Sequencing Kit V14 (Nanopore, SQK-LSK114). The libraries were sequenced using a PromethION platform (BGI, Hong Kong).