Myceliar growth of 90 Fusarium strains os F. acuminatum, F. chlamydosporum, F. culmorum, F. equiseti, F.verticillioides, F. oxysporum, F. proliferatum, F. solani an F. sambucinum isolated from fluvial channels and sea beds of the south-eastern coast of Spain was tested on potato-dextrose-agar adjusted to different matric potentials with either KCl or NaCl (from - 1.50 to - 144.54 bars)

Cara Garcia, Miguel de

Iglesias Gonzalez, Concepcion

Palmero Llamas, Daniel

Tello Marquina, Julio

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Growth of Fusarium species as affected by temperature and osmotic potential (NaCl and KCl) interactions.

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greater presence of Fusarium in river water could be due to soil
particles and organic matter content from run-off of the river
banks after rainfall events. The presence of species found in the
sea could be the consequence of river water flowing into the sea.
Nevertheless, other explanations cannot be excluded.
GROWTH OF FUSARIUM SPECIES AS AFFECTED BY TEM-
PERATURE AND OSMOTIC POTENTIAL (NaCl AND KCl)
INTERACTIONS. D. Palmero1, M. de Cara2, C. Iglesias1 and
J.C. Tello2. 1Universidad Politécnica de Madrid, EUIT Agrícola,
Ciudad Universitaria s/n. 28040 Madrid, Spain. 2Universidad de
Almería, Departamento de Producción Vegetal. Cañada de San Ur-
bano s/n.; 04120 Almería, Spain. E-mail: daniel.palmero@upm.es 
Myceliar growth of 90 Fusarium strains of F. acuminatum, F.
chlamydosporum, F. culmorum, F. equiseti, F. verticillioides, F.
oxysporum, F. proliferatum, F. solani and F. sambucinum isolated
from fluvial channels and sea beds of the south-eastern coast of
Spain was tested on potato-dextrose-agar adjusted to different
matric potentials with either KCl or NaCl (from -1.50 to -144.54
bars). Fungal growth was determined by measuring colony diam-
eter in four days time, with a temperature of incubation from 15
to 35ºC. Myceliar growth was maximal at 25ºC. Quantity and fre-
quency pattern of myceliar growth of Fusarium species were sen-
sitively different at 15 and 25ºC, with the maximum growth at the
lower water potential tested (- 1.50 bars); and the 35ºC pattern,
with a maximum of myceliar growth at -13.79 bars. Results show
how the effect of osmotic potential was independent of the salt
type. The general pattern emerging was that isolates showed de-
clining growth at potentials below -41.79 bars. Significant statisti-
cal differences were found in myceliar response to water potential
and temperature separately and to their interactions.  Growing
frequencies were progressive minor as the water potential
dropped, but growth was registered at -99.56 bars. The response
to the salinity of the media has a markedly specific behaviour. F.
solani, F. oxysporum, F. proliferatum, F. equiseti and F. verticil-
lioides growing pattern changes with the temperature. It was ob-
served how fungal growth of seabed isolates at 35ºC was
favoured with salt addition in the first or second osmotic pressure
tested. These results could indicate that some Fusaria have the ca-
pacity of metabolic adaptation to low water potential environ-
ments. Differences founded between frequency and growth
quantity could indicate that biological factors that determine the
growing capacity and those that determine the final growth after
4 days of incubation are affected in different ways by water po-
tential.
DIVERSITY OF FUMONISIN-PRODUCING FUSARIUM
STRAINS ISOLATED FROM FRENCH CORN. L. Pinson-
Gadais, G. Marchegay, C. Ducos, F. Turtaut, C. Barreau and F.
Richard-Forget. UR 1264 Mycologie et Sécurité des Aliments, In-
stitut National de la Recherche Agronomique, 33883 Villenave
d’Ornon, France. E-mail: lpinson@bordeaux.inra.fr 
In Europe, the occurrence of fumonisins B (FB) on maize is
mainly ascribed to Fusarium verticillioides and F. proliferatum.
Although the risk is correlated with some Fusarium species, it al-
so depends on the ability of strains to produce toxins. Control-
ling the mycotoxin risk requires to assess the diversity of fumon-
isins producers. Eighty-five strains of the Liseola section were
isolated from French corn harvests in 2004 and 2006: F. verticil-
lioides (63), F. proliferatum (12), F. subglutinans (10). The strains
were grown on autoclaved corn (25°C, 1 aw, 21 days) and their
ability to produce fumonisins was assessed. This characterisation
indicated that F. verticillioides and F. proliferatum strains were
able to produce fumonisins, mainly FB1. A high diversity in the
levels of toxins was observed (19 to 4500 ppm). Our data sug-
gest that F. proliferatum strains produce less fumonisins than F.
verticillioides strains. Among the 10 F. subglutinans strains stud-
ied, six were shown to produce low levels of FB1. It was investi-
gated if this variability in levels of produced toxins could be
linked with differences inside the sequences of the FUM gene
cluster. For F. verticillioides and F. proliferatum strains, whatever
the considered gene or intergenic sequences studied, no differ-
ences were observed between high and low FB1 producers.
None of the FUM genes and intergenic regions studied was am-
plified for the 10 F. subglutinans strains, although some were
characterised as toxigenic. This result suggests that the FUM
genes of F. subglutinans strains are largely different from that of
F. verticillioides and F. proliferatum.
FUSARIUM spp. ASSOCIATED WITH LEAF LITTER FROM
MABIRA TROPICAL FOREST, UGANDA. S. Serani and H.K.
Taligoola. Makerere University, Department of Botany, Faculty of 
Science, P.O. Box 7062 Kampala, Uganda. E-mail: serasn@yahoo.com
Fungi may live as saprobes, which bring about decay of organ-
ic materials or as parasites, which attack living organisms thus
causing disease of plants and animals. Fungi perform essential
roles in every terrestrial ecosystem, as decomposers of dead or-
ganic matter; releasing nutrients and supporting plant life. Leaf
litter at different stages of decomposition was collected from the
forest floor under a canopy of known tree species in Mabira
Tropical Forest in Central Uganda. A number of Fusarium
species were isolated from leaf litter of four different tree species,
i.e. F. lateritium, F. semitectum, F. solani, F. graminearum, Nectria
sp. The tree species were Ficus valis, Celtis sp., Cola gigantica and
Chrysophyllum sp. Most of the species were isolated in the sec-
ond and third stage of decomposition and there was no signifi-
cant difference in isolation frequency for the tree species. 
GENETIC VARIABILITY OF A FUSARIUM SEMITECTUM
POPULATION ISOLATED FROM MEDICAGO SATIVA L.
CULTIVATED IN AN UNIQUE FIELD IN NORTHERN ITALY.
M. Zaccardelli1, M. Carelli2 and V. Balmas3. 1CRA, Centro di
Ricerca per l’Orticoltura, Gruppo di Ricerca di Battipaglia, SS 18
204, 84091 Battipaglia (SA), Italy. 2CRA, Centro di Ricerca per le
Produzioni Foraggere e Lattiero-Casearie, Viale Piacenza 29, 26900
Lodi, Italy. 3Dipartimento di Protezione delle Piante, Università de-
gli Studi, Via E. De Nicola 9, 07100 Sassari, Italy. E-mail: massimo. 
zaccardelli@entecra.it
Fusarium semitectum Berk. & Ravenel is often isolated from
soil and plant tissues, where it can be associated to complex dis-
eases. It has been reported as pathogenic when inoculated on
different hosts, however it is not considered as an important
plant pathogen. During summer and autumn 1998, several iso-
lates of F. semitectum were obtained from diseased alfalfa (Med-
icago sativa L.) cultivated in different fields in the Po Valley
(Northern Italy). The plants showed chlorosis and wilting symp-
toms. A population of F. semitectum, providing from an unique
alfalfa field in Po Valley (Lodi district), were analysed for DNA
polymorphism to study genetic variability of the fungus from an
unique host in a very restricted cultivation area. Isolations were
performed on potato dextrose agar (PDA) and on Komada’s
substrate from basal portions of alfalfa stem. Monosporic cul-
Journal of Plant Pathology (2008), 90 (3, Supplement), S3.47-S3.50 S3.49
014_Session5_S47  16-05-2008  17:33  Pagina 49


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Growth of Fusarium species as affected by temperature and osmotic potential (NaCl and KCl) interactions.

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