INVESTIGADORES
BARROS German Gustavo
congresos y reuniones científicas
Título:
SSR analysis and competition assay in peanut and maize using non-aflatoxigenic Aspergillus flavus strains in Argentina
Autor/es:
ALANIZ ZANON M.S.; BARROS, G.; COTTY, P.; CHULZE, S.
Reunión:
Conferencia; International Mycotoxin Conference; 2014
Resumen:
Biological control based on
competitive exclusion has been developed as one of the most promising
strategies for management of aflatoxins in several crops including peanuts (Arachis hypogaea L.) and maize (Zea mays). This type of biocontrol involves
applying one or more non-toxigenic Aspergillus
flavus isolate to developing crops in order to competitively exclude aflatoxin
producers. In so doing, this technique modifies the fungal communities associated to
crops and increases crop safety. The general aim of the present work was selection of non-aflatoxigenic A. flavus isolates that have potential
for biocontrol from 47 isolates previously characterized with morphological,
physiological, molecular and genetic parameters. The characterized fungi were
isolated from several agricultural regions of Córdoba province. The work also
sought to perform a preliminary evaluation of variation among the isolates in competitive
ability against two high aflatoxin producers in laboratory assays on viable
maize and peanut. Isolate genetic
diversity was evaluated with microsatellite (also called SSRs or Simple
Sequence Repeats) analyses. Isolates with particular SSR haplotypes were not
specific to either region or isolation date. Representative isolates for each
of 6 haplotypes were compared for efficacy in the competition assay. Competition
was performed in both maize grains and peanut pods. In order to determine
influences of the selected fungi on the aflatoxin content of the crops aflatoxin
production was quantified with quantitative TLC. In general, all six evaluated
isolates (6) were able to both competitively displace the co-inoculated
aflatoxin producing isolate and decrease aflatoxin concentrations in both crops.
In peanut, the most effective aflatoxin contamination reducers of both of B1
and B2 were isolates AF100G and AFCHG2, with reduction percentages of
90 to 100% when paired with either aflatoxin-producer. In maize, isolates AFCHG2
and GD070 were the most effective at reducing contamination resulting in 94 and 78% reductions in total aflatoxins
against aflatoxin producer AFCHG2 and, 93 and 92% against aflatoxin-producer GD070,
respectively. The excellent in vivo results
reported here supportevaluation of several of the tested non-aflatoxigenic
isolates in aflatoxin management field trials either individually or in formulations
that combine multiple non-aflatoxin producing isolates.