Rounding up the annual ryegrass genome: High-quality reference genome of Lolium rigidum

The genome of the major agricultural weed species, annual ryegrass (Lolium rigidum) was assembled, annotated and analysed. Annual ryegrass is a major weed in grain cropping, and has the remarkable capacity to evolve resistance to herbicides with various modes of action. The chromosome-level assembly was achieved using short- and long-read sequencing in combination with Hi-C mapping. The assembly size is 2.44 Gb with N-50 = 361.79 Mb across 1,764 scaffolds where the seven longest sequences correspond to the seven chromosomes. Genome completeness assessed through BUSCO returned a 99.8% score for complete (unique and duplicated) and fragmented genes using the Viridiplantae set. We found evidence for the expansion of herbicide resistance-related gene families including detoxification genes. The reference genome of L. rigidum is a critical asset for leveraging genetic information for the management of this highly problematic weed species.

Automated summary

The genome of the major agricultural weed species, annual ryegrass (Lolium rigidum), was assembled, annotated and analyzed. The study revealed the remarkable capacity of this weed to evolve resistance to herbicides with various modes of action. The researchers achieved a chromosome-level assembly using advanced sequencing techniques and also found evidence for the expansion of herbicide resistance-related gene families. This research provides important genetic information for the management of this problematic weed species.