Book of Abstracts (PDF) - International Mycological Association

IMC7 Main Congress Theme III: PATHOGENS AND NUISANCES, FOOD AND MEDICINE Posters
pycnidial cells. In the apical region of conidiophore
numerous vesicles were found. Ontogeny of conidia was
holoblastic. Contents of the conidiophore and conidium
were continuous during migration of full complement of
organelles into conidial cell. Then a delimiting septum
formed. Conidia were liberated schizolytically. Fusiform,
septate conidia with numerous mitochondria, ribosomes
and large lipid droplets were observed in the mucilagefilled
central cavity of pycnidium. The conidium organelles
were difficult to distinguish. Conidial wall consisted of two
layers. The outer layer was moderately electron-dense wirg
fibrillar surface.
877 - Breeding of Pleurotus and Lentinula hybrids by
pairings of neohaplonts for commercial cultivation
R. Ramirez Carrillo * & H. Leal Lara
Department of Food Science and Biotechnology, 04510
Ciudad Universitaria, Col. Copilco, Mexico D.F., Mexico.
- E-mail: rebecarc@servidor.unam.mx
Cultivation of Lentinula edodes is slow and rather
inefficient and aggressive strains, able to grow on a wide
range of substrates, like hybrids of Lentinula with
Pleurotus is a promising option. Interspecies hybrids
cannot be obtained by conventional breeding, they have
been produced only by protoplasts fusion, but such hybrids
are sterile and highly unstable. Dedikaryotization yields the
2 monokaryotic components of a strain and it has been
used for improving strains of the same species. Therefore,
7 strains of Lentinula and 3 of Pleurotus were
dedikaryotized, Lentinula neohaplonts were classified in 4
incompatibility groups and Pleurotus neohaplonts were
also classified in 4 groups. Surprisingly, matings of
neohaplonts of Lentinula and Pleurotus yielded 73 hybrids
and only 5 negative pairings. From 19 hybrids cultivated
on fermented straw, 2 produced fruit bodies with Lentinula
morphology in the first flushes while 15 hybrids yielded
Pleurotus morphology with BE around 160%. Parental
strains of Lentinula and Pleurotus yielded fruit bodies with
the typical morphology for each species; BE values were
around 148 to 182% for Pleurotus and 24 to 261% for
Lentinula. In the meiotic progeny from 3 hybrids, 4 mating
types were present in 1:1:1:1 ratio (p 95%), confirming
fertility of the hybrids and inheritance of tetrapolar
heterothallic compatibility. Separation of these organisms
into 2 different strains has to be reconsidered in view of
these results.
878 - Influence of environmental factors and fungicides
on growth and deoxynivalenol production by Fusarium
graminearum
M.L Ramirez 1* , S.N. Chulze 2 & N. Magan 1
1 Applied Mycology Group, Cranfield Biotechnology
Centre, Cranfield University, Silsoe, Bedford MK45 4DT,
U.K. - 2 Dpto. Microbiologia e Inmunologia, Universidad
Nacional de Rio Cuarto, Ruta 36 Km 601, Rio Cuarto,
264
Book of Abstracts
Cordoba., Argentina. - E-mail:
m.l.ramirez@cranfield.ac.uk
The impact of five fungicides (prochloraz, propioconazole,
epoxiconazole, tebuconazole and azoxystrobyn, 0.5-50
ppm) on growth of F. graminearum was evaluated in
relation to water activity (aW, 0.99, 0.97, 0.95) and
temperature (15 and 25 °C) on wheat-based media (in
vitro). All fungicides reduce growth rates when compared
to the control, and this reduction increased as the fungicide
concentration increased. In general, none of the isolates
was able to grow in the presence of any fungicide at
concentrations higher than 15 ppm, regardless of the
a W/temperature regime. The same fungicides were used in a
second study on wheat grain (in situ), in order to evaluate
the effect of two concentrations (0.5 and 5 ppm), three a W
levels (0.995, 0.99 and 0.97) and two temperatures (15 and
25 °C) and their interaction on growth rate and
deoxynivalenol (DON) production by F. graminearum. All
fungicides showed inhibition of growth at both
concentrations in most conditions. The fungicides tested
were less effective on grain in controlling growth than in in
vitro studies. All fungicides showed DON stimulation or
reduction in at least one of the conditions assayed. Our
results show that stimulation or reduction in DON
production in the presence of fungicides is influenced by
complex interactions between aW, temperature, fungicide
concentration and time of incubation in both strains
studied. Such information is critical for effective fungicide
control of Fusarium head blight of wheat.
879 - Relationship between osmotic and matric
potential, growth and endogenous accumulation of
polyols and sugars in colonies of Fusarium
graminearum
M.L Ramirez 1* , S.N. Chulze 2 & N. Magan 1
1 Applied Mycology Group, Cranfield Biotechnology
Centre, Cranfield University, Silsoe, Bedford MK45 4DT,
U.K. - 2 Dpto. Microbiologia e Inmunologia, Universidad
Nacional de Rio Cuarto, Ruta 36 Km 601, Rio Cuarto,
Cordoba., Argentina. - E-mail:
m.l.ramirez@cranfield.ac.uk
The effect of ionic (NaCl) and non-ionic osmotic potential
(glycerol) and matric potential (PEG 8000) in the range -
0.7 to -11.2 MPa, on growth of F. graminearum at 15 and
25 °C on 2% wheat flour agar has been studied. The effect
of stresses on endogenous accumulation of low and high wt
polyols (glycerol, erythritol, arabitol and mannitol) and
sugars (glucose and trehalose) in whole colonies of this
fungus were also quantified. At 25 °C and high water
potential growth rates on matric-modified media were
higher than on osmotic-modified media. However, in the
same range of water potentials on osmotically modified
media, F. graminearum grew faster on NaCl than on
glycerol-amended media. In general, the concentration of
total polyols in whole colonies of F. graminearum
increased as osmotic and matric potential was reduced to -
8.4 MPa. Also marked differences in the ratios of low and
high mol wt polyols in mycelial colonies were found.
There was an increase in the glycerol content with a