A phased chromosome-level genome and full mitochondrial sequence for the dikaryotic myrtle rust pathogen, Austropuccinia psidii

Abstract

The fungal plant pathogen Austropuccinia psidii is spreading globally and causing myrtle rust disease symptoms on plants in the family Myrtaceae. A. psidii is dikaryotic, with two nuclei that do not exchange genetic material during the dominant phase of its life-cycle. Phased and scaffolded genome resources for rust fungi are important for understanding heterozygosity, mechanisms of pathogenicity, pathogen population structure and for determining the likelihood of disease spread. We have assembled a chromosome-level phased genome for the pandemic biotype of A. psidii and, for the first time, show that each nucleus contains 18 chromosomes, in line with other distantly related rust fungi. We show synteny between the two haplo-phased genomes and provide a new tool, ChromSyn, that enables efficient comparisons between chromosomes based on conserved genes. Our genome resource includes a fully assembled and circularised mitochondrial sequence for the pandemic biotype.