INVESTIGADORES
ANDREU Adriana Balbina
congresos y reuniones científicas
Título:
Cell wall α-1, 3-glucans from a biocontrol isolate of Rhizoctonia elicits plant defense responses and induces protection against Rhizoctonia solani AG-3 and Fusarium solani f. sp. Eumartii.
Autor/es:
WOLSKI E.A.; DALEO G.R.; ANDREU A. B.
Lugar:
Alemania, Berlin, 20-23rd August 2008.
Reunión:
Congreso; International Symposium on Rhizoctonia; 2008
Institución organizadora:
TU Berlin Servicegesellschaft mbH
Resumen:
Plants are continually exposed to a vast number of
pathogens and its recognition is mediated by signal molecules called elicitors.
Most elicitors from fungal cell walls have been described as ß-glucans. In a previous
work we isolated and characterized a cell wall α-1,3-glucan
from non-pathogenic binucleate Rhizoctonia
(BNR), which have elicitor activity. In this work we showed that the α-1,
3-glucan not only induced ß-1,3-glucanase activity, but also chitinase activity
in potato sprouts. We also observed an increase of pathogenesis-related
proteins (PRs), for example: PR-2 (ß-1,3-glucanase), PR-3 (chitinase) and PR-5
(thaumatin-like protein). Histological studies showed an increase in cell wall
deposition of callose and lignin, which contribute to cell wall reinforcement. In
addition, the a-1,3-glucan
induced protection of potato against two fungal diseases, Rhizoctonia canker
and Dry rot. Protection assays showed that pre-treatment of potato sprouts and
potato tubers with the glucan results in a 40% of protection against
Rhizoctonia canker and 60% protection against dry rot. On the other hand, we
prepared an antibody against the a-1,3-glucan to localize it by transmission
electron microscopy. The results showed the presence of the a-1,3-glucan
in intercellular spaces and along the cell walls, mainly on the inner layers.
This result and the presence of the a-1,3-glucan in liquid culture, where BNR was
grown, confirmed that the a-glucan had been secreted. In addition, α-glucanase
activity in potato sprouts was detected using cell wall glucans from the
pathogenic isolate R. solani AG-3 as
substrates; whereas, when cell wall glucans from BNR isolate were used, no
α-glucanase activity was detected. The present study is the first report of an
α-glucan elicitor from Rhizoctonia,
that may be important as a biocontrol agent. In addition, our results suggest
that the presence of α-1,3-glucans could be associated
with plantfungi interactions.
Supported
by: CONICET, CIP, UNMDP.