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The wood properties of western redcedar (Thuja plicata) (WRC) are revered in traditional practices by Pacific Coast First Nations and valued for speciality commercial purposes. In the near future, WRC harvesting will shift to second growth from old-growth, however, its cultural significance will persist, and the superior physical and chemical properties of the wood mean that it will remain in high demand. Investigating and understanding the adaptations of the species to environmental and pathogen stress in the face of changing climates can assure a sustainable supply of WRC. Of the pathogens affecting WRC, cedar leaf blight (Didymascella thujina) (CLB) is the most severe. This foliar disease infects the leaflets of seedlings and mature trees, causing a loss of photosynthetic area resulting in decreased growth or mortality. The disease is more severe on nursery seedlings than mature trees. Future projected climates in WRC's native range are expected to increase the prevalence of, and damage from CLB. This review summarizes the state of knowledge and emphasizes recent advances in the understanding of the Thuja – Didymascella pathosystem. [ABSTRACT FROM AUTHOR]

Heterotrimeric G proteins are best known for their role in the transduction of extracellular signals to various downstream effectors. G proteins in higher eukaryotes are intensively studied; however, their roles in foliar pathogens are still elusive. In this study, we cloned the gene Stgg1 encoding G protein γ subunit in Setosphaeria turcica and investigated its function by RNA interference technology. Three independent Stgg1 targeted RNAi mutants R3, R5 and R6 with diverse silencing efficiency were generated. Knock-down of Stgg1 resulted in a significant reduction in mRNA levels of the genes encoding Gα (Stga1, Stga2, Stga3) but not for Gβ (Stgb1). Stgg1 RNAi mutants exhibited significantly elongated hyphal cells with blocked conidium production. In addition, Stgg1 RNAi mutants all appeared in lighter colony colour compatible with inhibited secondary metabolites. Further assays demonstrated that Stgg1 was required for biosynthesis of melanin and HT-toxin activity. Furthermore, down-regulation of Stgg1 largely inhibited the inflection capacity. Thus, we proposed that Stgg1 played crucial roles in conidiation, secondary metabolite production and pathogenicity of S. turcica and is, therefore, an ideal target for drug design against foliar pathogens. [ABSTRACT FROM AUTHOR]