Sampling seeds in storage facilities: hunting for Fusarium infection

Fusarium graminearum is one of the most studied fungal pathogens in the world. A great number of scientific publications are
available that describe morphology, physiology, toxicology and genome of this species. On the other hand, F. poae is less widely
studied but its importance as toxigenic fungus has been recently recognized. In Italy, F. poae is rapidly becoming one of the most widespread Fusarium species on small seeds cereals heads. Soft wheat is often colonised by these species. So far, Fusarium Head
Blight (FHB) symptoms have been always investigated on soft wheat heads or on seeds collected in the field during harvesting.
This poses a problem, as the seed industry and the national seed certification services would be interested to know the percentage
of infection of seeds stored into facilities after processing and how infection is distributed inside seed lots. In order to study these aspects, we performed a mycological screening on soft wheat seed samples collected inside a facility, sampling directly from bags intended for seed trading. Sampling was performed during the years 2013 and 2014. The screening, carried out on Potato Dextrose Agar
(PDA), was limited to organic soft wheat coming from Northern and Central Italy. Putative F. graminearum and F. poae colonies were selected and single spores purified and confirmed through microscope observations and through a molecular identification.
Seed samples resulted to be infected at a very low level. Though some lack of homogeneity was observed among the lots, this was
sufficiently small to allow statistical studies.