EFS12- Book of abstracts - Contact
EFS12- Book of abstracts - Contact
EFS12- Book of abstracts - Contact
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SESSION 3: PATHOGENESIS – EPIDEMIOLOGY AND POPULATION<br />
GENETICS<br />
P44 - A rapid in vitro assay to select mutants <strong>of</strong><br />
Fusarium impaired in pathogenicity.<br />
F. Spanu 1 , B. Scherm 1 , V. Balmas 1 , I. Camboni 1 , A. Marcello 1 , M. Pasquali 2 ,<br />
Q. Migheli 1<br />
1 Dipartimento di Agraria - Plant Pathology and Entomology Unit and Unità di ricerca Istituto Nazionale<br />
di Biostrutture e Biosistemi, Università degli Studi di Sassari, Via E. De Nicola 9, I-07100 Sassari, Italy.<br />
2 CRP - Gabriel Lippmann, Environment and Agro-Biotechology Department, 41, rue du Brill, L-4422<br />
Belvaux, Luxembourg<br />
E-mail: fspanu@uniss.it<br />
Fusarium culmorum, along with Fusarium graminearum and Fusarium<br />
pseudograminearum, is one <strong>of</strong> the most important pathogens <strong>of</strong> wheat worldwide,<br />
causing foot and root rot (FRR) and fusarium head blight (FHB). In the central and<br />
southern areas <strong>of</strong> Italy, F. culmorum is predominant as the FRR causal agent on<br />
durum wheat. Symptoms include pre- and post-emergence death <strong>of</strong> the<br />
seedlings, brown discoloration on coleoptiles, roots and pseudostem, brown<br />
lesions on the basal portion <strong>of</strong> the stem, tiller abortion and formation <strong>of</strong><br />
whiteheads, resulting from premature death <strong>of</strong> the plant. As a consequence,<br />
significant yield losses are reported. Knowledge on genes triggering FRR on<br />
durum wheat seedlings is still limited. F. culmorum mutants originating by random<br />
and targeted insertional mutagenesis methods are being analysed in their<br />
developmental capability, level <strong>of</strong> virulence and aggressiveness during the first<br />
steps <strong>of</strong> kernel colonisation. However, greenhouse experiments are difficult to<br />
perform for large collections <strong>of</strong> putative mutant strains due to the need <strong>of</strong> large<br />
facilities, temperature and humidity control, and the time required (three to four<br />
weeks after inoculation) to observe the first symptoms. We have developed a<br />
simple in vitro pre-selection bioassay to analyse the development <strong>of</strong> fungal<br />
hyphae during the first steps <strong>of</strong> colonisation, consisting in placing - for each strain<br />
to analyse - 10 mycelium discs (Ø 90 mm) bearing one durum wheat seed into a<br />
Petri dish and incubating 3 days in the dark. While the wild-type strain entirely<br />
surrounded the seed by forming a complex network <strong>of</strong> thick and sturdy hyphae,<br />
thus preventing germination before coleoptile growth, mutant strains impaired in<br />
pathogenicity did not hinder the emergence <strong>of</strong> the primary root from the caryopsis.<br />
This method proved to be as reliable as in planta assays, suggesting a potential<br />
role for general use <strong>of</strong> in vitro testing <strong>of</strong> FRR-impaired mutants. We propose to<br />
further validate this test on a broader collection <strong>of</strong> strains altered in their virulence<br />
within the frame <strong>of</strong> an inter-laboratory collaboration.<br />
Keywords: Foot and root rot, durum wheat, seed germination, bioassay, fungal<br />
virulence<br />
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