Site specific distribution of oak rhizosphere associated oomycetes revealed by cytochrome c oxidase subunit II metabarcoding

The phylum Oomycota comprises important tree pathogens like Phytophthora quercina, involved in central European oak decline, and P. cinnamomi shown to affect holm oaks among many other hosts. Despite the importance to study the distribution, dispersal and niche partitioning of this phylum, metabarcoding surveys and studies considering environmental factors that could explain oomycete community patterns are still rare. We investigated oomycetes in the rhizosphere of evergreen oaks in a Spanish oak woodland using metabarcoding based on Illumina sequencing of the taxonomic marker cytochrome c oxidase subunit II (cox2). We developed an approach amplifying a 333 bp long fragment using the forward primer Hud-F (Hudspeth, Nadler, & Hudspeth, 2000) and a reverse primer found using DegePrime (Hugerth et al., 2014). Factors reflecting topo-edaphic conditions and tree health were linked to oomycete community patterns. The majority of detected OTUs belonged to the Peronosporales. Most taxa were...