INBA   12521
INSTITUTO DE INVESTIGACIONES EN BIOCIENCIAS AGRICOLAS Y AMBIENTALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Diversity of lepidopteran specific Bacillus thuringiensis strains from Argentina
Autor/es:
M.E. VIDAL DOMÍNGUEZ; L.M. DÍAZ; G.L. SALERNO; C.M. BERÓN
Lugar:
San Miguel de Tucumán
Reunión:
Congreso; VII Congreso Argentino de Microbiología General; 2011
Institución organizadora:
Sociedad Argentina de Microbiología General
Resumen:
Several lepidopteran species cause significant damage
to many agricultural important crops in Argentina. Among them Anticarsia
gemmatalis and Spodoptera frugiperda are important insect pests of
soybean, corn, wheat, and forage grasses. Currently, the use of
entomopathogenic bacteria Bacillus thuringiensis as biolarvicide offers
a viable alternative for insect control. This bacterium produces proteinaceous
inclusions during sporulation that are toxic towards insect larvae upon
ingestion. The parasporal body of B. thuringiensis consists of one or
more insecticidal crystal proteins (ICP). Most ICP-coding genes are located in
megaplasmids.
Typically, B. thuringiensis harbours a set of
native plasmids, which vary in number from 1 to 17 and in size from 2 kb to 600
kb. Plasmid patterns and different PCR approaches have frequently been used to
characterize B. thuringiensis strains around the world.
In this work, we described the characterization of
nine B. thuringiensis strains isolated from soil samples of Argentina.
In preliminary tests, we performed mortality assays to determine the toxicity
spectrum of these strains. They were highly toxic against A. gemmatalis and
moderately toxic against S. frugiperda. Also, protein patterns of
spore-crystal complexes analyzed by SDS-PAGE showed similar patterns with major
polypeptides of about 70 and 130 kDa. Molecular characterization of these
strains was made by determining plasmid patterns, nested-PCR and, denaturing
gradient gel electrophoresis (DGGE). According their plasmidic pattern, the
isolates were classified in three groups containing four, eight or no plasmids.
On the other hand, characterization of cry gene content in these strains
was performed by a nested-PCR and DGGE approaches both with degenerate primers.
Using DGGE methodology we got identical profiles in eight strains except in
strain FCC25. Additionally, these methods allowed us to identify partial cry
sequences that are currently under analysis and will be further used to recognize
and characterize new cry sequences.