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allied
academies
Archives of Industrial Biotechnology | Volume 2
May 14-15, 2018 | Montreal, Canada
World Yeast Congress
T
he use of yeast species represents a promising strategy
as biocontrol agents. Different yeast species are able
to prevent infection, decrease host tissue colonization,
and reduce plant pathogen survival and sporulation with
varying degrees of efficiency. Despite the known biological
roles of yeasts in the environment, however, much remains
to be discovered regarding its modes of action in distinct
environments and their antagonistic behavior toward other
organisms. The purpose of this study was to isolate and
select yeasts from citrus leaves, flowers and fruits as well
as from citrus growing soils and determine the adequate
strains for post-harvest diseases biocontrol both in vitro
and in vivo. Additionally, to evaluate the modes of action
of yeasts isolates that previously shown to be effective
in controlling sour rot (
Geotrichum citri-aurantii
), green
mold (
Penicillium digitatum
) and blue mold (
P. italicum
)
in citrus fruits and, finally, to purify and characterize the
killer toxin produced by yeast isolates and, verify their
antagonistic activity on pathogens that occur in citrus
postharvest. The results obtained in this study showed that
the isolates ACBL-42 (
Sporobolomyces koalae
) and ACBL-
77 (
Aureobasidium pullulans
), showed efficient control as
a preventive and as well as curative measure for sour rot
and were able to produce chitinase in the presence of the
G.
citri-aurantii
cell wall. A. pullulans produced killer toxin
against Geotrichum.
Saccharomyces cerevisiae
(ACB-K1)
when applied as a preventive measure against P.
digitatum
promoted 73% healthy fruits. This yeast provided 100%
disease control in ‘Tahiti’ acid lime fruits under refrigeration
(10oC and 95%RH) when combined with a quarter dose of
imazalil fungicide. Studies about modes of action of this
yeast against
Geotrichum citri-aurantii
demonstrated that
ACB-K1 produced hydrolytic enzymes (chitinases and β-1,3-
glucanases), killer activity and inhibited conidial germination.
The multiple modes of action (killer activity, production of
chitinase and inhibition of conidial germination) presented
by the Candida stellimalicola strains against P.
italicum
may
explain why these yeasts provided control of blue mold in
citrus fruits.
e:
katia@ccsm.brYeast species as biological control agents of fungal plant pathogens
Katia Cristina Kupper
Centro de Citricultura “Sylvio Moreira”, Brazil