Whole-Genome Sequence of the Phlox Powdery Mildew Pathogen Golovinomyces magnicellulatus Strain FPH2017-1

Powdery mildew (PM) fungi are obligate biotrophs capable of infecting diverse plant hosts, ranging from monocotyledonous agricultural crops to dicotyledonous ornamental crops. The PM lifestyle poses significant challenges for studying these pathogens in isolation from their host. We present a draft genome of Golovinomyces magnicellulatus, a host-specific PM on Phlox species.

G olovinomyces magnicellulatus (Leotiomycetes, Ascomycota) is an obligate hostspecific fungal biotroph that causes powdery mildew (PM) disease on ornamental plants in the Phlox genus (1). Due to difficulties in growing PM fungi under axenic conditions, little is known regarding the genetic and evolutionary bases of their lifestyles, presenting an opportunity to gain insight through a genome-focused approach.
G. magnicellulatus strain FPH2017-1 was isolated from Phlox paniculata in Leipsic, Ohio. A single spore was isolated on a detached leaf bioassay (2) and grown on P. paniculata 'Starfire' plants in a growth chamber. Spores were harvested periodically over 1 month by rinsing infected leaves with 0.1% Tween solution and then filtering with Miracloth and stabilizing using 10 mM Tris buffer (pH 7). The solution was centrifuged, and the resulting pellet was immersed in liquid nitrogen and kept at -80°C. DNA was extracted from the pellet using the DNeasy plant minikit (Qiagen).
DNA libraries were prepared using the NEBNext Ultra II DNA library prep kit and sequenced using the Illumina MiSeq PE300 platform. Unsheared DNA extracts were prepared using a ligation sequencing kit (SQK-LSK109) and sequenced using MinION (Oxford Nanopore Technologies).
We annotated the assembly using three iterations of a MAKER v.2.31.9 (9) pipeline. In the first iteration, we provided MAKER with transcriptome sequencing (RNA-seq) data of Golovinomyces cichoracearum (http://genome.jgi.doe.gov/Golci1) and 10 [12]). For the final iteration, we provided MAKER with updated evidence from SNAP and AUGUSTUS (both retrained using high-quality predictions from round 2) and set the option keep_preds to 1.
Many PM genomes are estimated to range in size from 120 to 220 Mb (13), due in part to high repeat content. Conversely, PMs generally possess fewer protein-coding genes (6,000 to 7,000) than other fungi (13,14). Our genome falls within the reported PM genome size, 129.9 Mb, while our annotation process recovered 8,172 proteincoding genes, more than generally reported (Table 1), which we attribute to the multiple lines of ab initio evidence used in the annotation process.
Data availability. This whole-genome shotgun project has been deposited at DDBJ/ENA/GenBank under the accession numbers VCMJ00000000 and PRJNA540711 (SRA database).

ACKNOWLEDGMENTS
The research described in this paper represents a portion of the dissertation submitted by C. Farinas to the Office of Graduate Studies of The Ohio State University to partially fulfill requirements for the Ph.D. degree in plant pathology.
This work was partially funded by the USDA-NIFA Hatch project number 1004939 and The Ohio State University Department of Plant Pathology. The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.