Multilocus Phylogeny, Seed Transmission and Epidemiological Aspects of Hyaloperonospora camelinae Causing Downy Mildew on Camelina sativa in Serbia

Camelina sativa is an oilseed crop of increasing importance. This study provides the first comprehensive characterization of downy mildew of camelina caused by Hyaloperonospora camelinae in Serbia. During 2023 and 2024, chlorotic lesions on leaves, pod deformation, and the presence of conidia, conidiophores, and oospores in necrotic leaves were observed. Selected isolates from both years showed typical H. camelinae morphology, and their pathogenicity was confirmed on camelina seedlings. Molecular identification and multilocus phylogenetic analysis based on ITS, LSU and COX-2 sequences confirmed the placement of H. camelinae within Hyaloperonospora and the identification of Serbian isolates. Seeds from infected plants showed a 74.2% germination rate (90% in the control) and a high transmission rate to progeny plants of 31.13%, confirming the epidemiological importance. Uneven distribution of H. camelinae within camelina tissue was documented, and apical plant parts, whether or not symptoms and sporulation were visible, had the highest detection rate. The stem, even when symptoms and sporulation were visible, proved unsuitable, exhibiting low detection rates and reliability. Disease dynamics, under field conditions, suggested points in time of incubation and sporulation of the primary and two secondary infections, providing a tool for disease monitoring in integrated disease management programs.