A homologue of the aflatoxin regulator AflJ regulates dothistromin biosynthesi
DsAflJ mutants had reduced levels of dothistromin toxin and gene expressions
Overexpression of AflJ results in elevated levels of aflatoxin, but not dothistromin.
Species-specificity of AflJ was suggested by lack of cross-species complementation.
Dothistroma septosporum is the cause of a recent DNB epidemic on P. tecunumanii in Colombia. Within- and between-species susceptibility also reported.
Rodas et al. 2015 “Dothistroma Needle Blight: an emerging epidemic caused by Dothistroma septosporum in Colombia”. Plant Pathology.
P. tecunumanii lowelevation provenances had the greatest susceptibility, followed by P. kesiya and P. oocarpa. Pinus maximinoi and high elevation P. tecunumanii had the lowest susceptibility.
Dothistroma septosporum spores only disperse short distances and during wet weather in northwest BC.
Boateng and Lewis 2015. Phytopathology.
Conidia were observed on spore traps from June to September during periods of rainfall.
It was rare to detect spores more than 2m away from inoculum sources.
The timing and number of conidia dispersed were strongly tied to the climatic variables, particularly rainfall and leaf wetness.
Abies - a new host genus for D. septosporum
Drenkhan et al. 2014. Forest Pathology 44, 250-254.
Abies concolor and A. alba
Cedrus – a new host genus for D. septosporum
Mullett and Fraser in press. Forest Pathology.
UK – C. atlantica glauca in the field
C. atlantica glauca, C. libani and C. deodara in artificial inoculations
Storage of D. septosporum cultures under 10% glycerol at -80°C or water at 4°C recommended
Fraser et al. 2015. Forest Pathology.
DNB severity influenced by other fungi
Ridout and Newcombe 2015. Forest Ecology and Management 337, 153-160.
Inoculation of P. ponderosa in the field in Idaho, USA with other fungi
Penicillium goetzii was the sole antagonist and reduced disease severity by nearly 7% compared to control needles.
Four of the fungi (Sydowia polyspora, Bionectria ochroleuca, Penicillium raistrickii, and a culturable species of Elytroderma) acted as pathogen enablers, increasing disease severity 4.7%, 4.2%, 3.6%, and 2.5%, respectively.
Relative susceptibility of Scottish P. sylvestris populations varies between sites
Fraser et al. In review. Plant Pathology.
Natural infection of 6 Scottish populations on 2 Scottish sites.
Between site variation in relative susceptibilities may be caused by:
Local adaptation of P. sylvestris populations
Local adaptation of D. septosporum populations
Pinus sylvestris and P. contorta have similar susceptibility to DNB in Scotland
Fraser et al. in review. Forest Pathology.
In naturally infected field experiments in Scotland both P. contorta and P. sylvestris were less susceptible than P. nigra ssp. laricio, P. nigra ssp. nigra, P. muricata and P. ponderosa.
Artificial inoculation experiments under controlled conditions did not give consistent results and conflicted with those of field experiments.
No evidence for between-isolate variation in virulence or an interaction between D. septosporum isolate and host relative susceptibility.