Proceedings of the XLVI Italian
Society of Agricultural Genetics - SIGA Annual Congress
Giardini
Naxos, Italy - 18/21 September, 2002
ISBN 88-900622-3-1
Poster
Abstract - 3.22
AcMNPV
chi a protein produced in E. coli is
potentially useful for plant defence
ARCIELLO S.*, FIANDRA L.**, GIORDANa B.**, de EGUILEOR M.***, RAO R.*
*)
Dip. di Scienze del Suolo, della Pianta e dell’Ambiente,
Università di Napoli “Federico II”, Via Università
100, 80055 Portici, Napoli
**)
Dip. di Biologia. Università di Milano, Via Celoria 26, 20133 Milano
***)
Dip. di Biologia Strutturale e Funzionale, Università
dell’Insubria, Via Dunant 3, 21100 Varese
Protein
purification, fungi toleration, peritrophic membrane perforation
Crop protection from pathogen organisms results crucial for modern
agriculture. Fungus and insect damages represent the main cause of loss of
production in agriculture (around 40%). Pest control, actually, is achieved
through chemical pesticides determining problems of residues and environmental
safety. The genetic engineering of plants to produce crops that are more
resistant to insect pests or fungal pathogens indicates that biological control
agents can play a larger role in integrated pest management and reduce our
dependence upon chemical pesticides. However the onset of pesticide resistances
in the target organisms has emphasized the need for more selective and effective
molecules. Among the genes that can be used to protect plants from
pathogen and pest infections, the best characterized genes are those that
encode the hydrolytic enzymes known as chitinases. These hydrolytic enzymes
inhibit the growth of many fungi in vitro by hydrolyzing
the chitin and b-glucan
of fungal cell walls. Furthermore, oligomeric products of digested chitin and b-glucan can act
as signal molecules to stimulate further defense responses. These lytic enzymes
have attracted much attention and have become very important resources in the
genetic engineering of crop plants for both insect
and fungi resistances.
The Multiple Nuclear Polyedrosis Virus of Autographa californica
(AcMNPV) have developed mechanisms to digest the insect host peritrophic
membrane in order to increase viroid penetration within the hosts. A chitinase gene (chi
A) has been identified within the AcMNPV genome and several independent studies
suggested that this gene might have a role in the host liquefaction (Hawtin et
al., 1997). AcMNPV chi A gene has been cloned and expressed in E. coli and the purified protein proved to be active against the two pathogen fungi, Alternaria
alternata and Botrytis cinerea. The protein was
also tested in vitro on peritrophic membranes isolated from Bombyx mori
larvae and proved to modify the permeability and to perforate the membrane as
observed at the electron microscopy.
The results of this study
provided evidences that chi A protein might be used as an alternative fungicide
and /or biopesticide which allows crop protection from different biotic
stresses, alone or in combination with other molecules.