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SESSION 1: FUSARIUM – GENETICS, GENOMICS AND SYSTEMS BIOLOGY
The linoleate synthase gene lds1 thoroughly affects
conidiogenesis and fumonisin synthesis in Fusarium
verticillioides
V. Scala 1 , M. Reverberi 1 , E. Camera 2 , M. Ludovici 2 , C. Dall’Asta 3 , M. Cirlini 2 ,
P. Giorni 4 , R. Gregori 4 , P. Battilani 4 , C. Fanelli 1
1 Environmental Biology Department, University of Rome “Sapienza”, Rome, Italy; 2 Laboratorio di
Fisiopatologia Cutanea e Centro Integrato di Metabolomica, Istituto Dermatologico San Gallicano
IRCCS, Roma, Italy; 3 Department of Organic and Industrial Chemistry, Food Chemistry & Natural
Substances Unit, University of Parma, Viale G.P. Usberti 17/A - 43100 Parma, Italy; 4 Istituto di
Entomologia e Patologia Vegetale, Università Cattolica del Sacro Cuore, via Emilia Parmense 84,
29122 Piacenza, Italy
E-mail: valeria.scala@uniroma1.it
Fusarium verticillioides is one of the most important fungal pathogens to cause
ear and stalk rot in maize, even if frequently asymptomatic, producing the harmful
series of compounds named fumonisins. Plant and fungal oxylipins have been
shown to play a crucial role in determining the outcome of the interaction between
the pathogen and its host in some pathosystems. Moreover, oxylipins result as
factors able to modulate the secondary metabolism in fungi. In this study we
inactivate the resident copy of the linoleate diol synthase 1 gene (lds1-acc. N.
FVEG_09294.3) of Fusarium verticillioides strain (ITEM 10027). LDS1 produces
mainly 8-HPODE and subsequently different di-HODEs. These specific oxylipins
are involved in the control of sexual/asexual reproduction, secondary metabolism
and pathogenicity in Aspergillus nidulans (Tsitsigiannis and Keller, 2007).
This study is aimed to find the function of this gene in F. verticillioides. The
genomic organization of lds1 gene is highly polymorphic. Thus the most affected
phenotype of lds1 mutant strains herein obtained presented multiple insertion
events. All the mutant strains are profoundly altered in asexual reproduction.
Notably, the lds1 strains hyper-sporulate and the one (T) with multiple insertion
events are the most affected in this feature (8,56 x 10 9 vs 6,40 x 10 7 conidia/mL of
the WT). Most important, mutant strains present a fumonisin profile (B series and
minor analogues) alteration directly proportional to the number of insertions,
being, also in this case, the T strain the most affected. This peculiar profile of an
oxylipin impaired mutant, i.e. hyper-sporulating and mycotoxin hyper-producer,
reminds the behavior of the ppoB mutant strain in A. nidulans (Tsitsigiannis and
Keller, 2007), being even ppoB a lds-coding gene. These results indicate that also
in F. verticillioides oxylipins play a major role in driving the fungus lifestyle and
these active compounds could act as repressor/inducer on asexual reproduction
and the secondary metabolism of this fungus.
Keywords: oxylipins, Fusarium, ppo, fumonisin
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