Environmental Microbiology (2022) 24, 1622-1637

Petros Skiadas, Joël Klein, Thomas Quiroz-Monnens, Joyce Elberse, Ronnie de Jonge, Guido Van den Ackerveken and Michael F. Seidl (2022)
Sexual reproduction contributes to the evolution of resistance-breaking isolates of the spinach pathogen Peronospora effusa
Environmental Microbiology 24 (3), 1622-1637
Abstract: Peronospora effusa causes downy mildew, the economically most important disease of cultivated spinach worldwide. To date, 19 P. effusa races have been denominated based on their capacity to break spinach resistances, but their genetic diversity and the evolutionary processes that contribute to race emergence are unknown. Here, we performed the first systematic analysis of P. effusa races showing that those emerge by both asexual and sexual reproduction. Specifically, we studied the diversity of 26 P. effusa isolates from 16 denominated races based on mitochondrial and nuclear comparative genomics. Mitochondrial genomes based on long-read sequencing coupled with diversity assessment based on short-read sequencing uncovered two mitochondrial haplogroups, each with distinct genome organization. Nuclear genome-wide comparisons of the 26 isolates revealed that 10 isolates from six races could clearly be divided into three asexually evolving groups, in concordance with their mitochondrial phylogeny. The remaining isolates showed signals of reticulated evolution and discordance between nuclear and mitochondrial phylogenies, suggesting that these evolved through sexual reproduction. Increased understanding of this pathogen's reproductive modes will provide the framework for future studies into the molecular mechanisms underlying race emergence and into the P. effusa-spinach interaction, thus assisting in sustainable production of spinach through knowledge-driven resistance breeding.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Full text of article

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Peronospora effusa	Spinach (Spinacia oleracea)	Netherlands