Effect of climate change on sporulation of the teleomorphs of species causing stem canker of brassicas.

are closely related sibling fungal pathogens that cause phoma leaf spotting, stem canker (blackleg) and stem necrosis of oilseed rape (). The disease is distributed worldwide, and it is one of the main causes of considerable decrease in seed yield and quality. Information about the time of ascospore release at a particular location provides important data for decision making in plant protection, thereby enabling fungicides to be used only when necessary and at optimal times and doses.

Molecular screening for avirulence alleles AvrLm1 and AvrLm6 in airborne inoculum of Leptosphaeria maculans and winter oilseed rape (Brassica napus) plants from Poland and the UK.

A combination of staining, light microscopy and SYBR green- and dual-labelled fluorescent probe-based qPCR chemistries with species- and gene-specific primers was employed to evaluate fluctuations in the aerial biomass of Leptosphaeria maculans spores captured by volumetric spore trappings in Poznan, Poland (2006, 2008) and Harpenden, UK (2002, 2006). Arising from these surveys, DNA samples extracted from Burkard spore-trap tapes were screened for fluctuation patterns in the frequencies of AvrLm1 and AvrLm6, the most prominent of the 15 genes that code for avirulence effectors in this Dothideomycete cause of the destructive phoma stem canker disease of oilseed rape worldwide. In Poznan, very low frequencies of AvrLm1 allele were found in the autumn of both 2006 and 2008, reflecting significantly increased cultivation of rape seed with Rlm1-based resistance.