Sequencing of RIL

Sorghum bicolor, one of the most important grass crops worldwide, harbors a high degree of genetic diversity. We constructed chromosome-level genome assemblies for two important sorghum inbred lines, TX2783 and TX436. The final high-quality reference assemblies consist of 19 and 18 scaffolds, respectively, with a contig N50 values of 25.6 and 20.3 Mb. Together with other public sorghum genomes, BTX623, TX430, and Rio, we identified extensive structural variations of various sizes using TX2783 as a reference. Genome-wide scanning for disease resistance (R) genes revealed high levels of diversity in these five sorghum accessions. To characterize the genes related to sugarcane aphid (SCA) resistance in TX2783, we mapped the resistance region on chromosome 6 using a recombinant inbred line (RIL) population. We also identified structural variations segregating for SCA resistance by Nanopore sequencing of another five genomes. This study provides the first overview of the extent of genomic structural variations, R genes in the sorghum population, and potential targets for disease resistance breeding.