ELICfI'ORS PROTEINS FROM ERWIMA AMYLOVORA AND ERWINIA CHRYSANTIIEMI
ELICITOR PROTEINS FROM ERWINIA AMYLOVORA AND ERWINIA CHRYSANTHEMI
V SHEVCHIK2, S GAUDRILLAULT1M A BARNY1 N HUGOUVIEUX-COTTE-PATTAT 2, M BOCCARAl
1 Pathologie Vegetale, INRA, INA P/G, 16 rue Claude Bernard 75005 PARIS FRANCE, 2 Laboratoire de Genetique Moleculaire des Microorganismes, UMR-CNRS, INSA, Bat 406, 20 avenue Einstein, 69621 Villeurbanne FRANCE
Background and objectives
Erwinia amylovora is a specialized parasite which is reponsible for fire blight on apple and pear trees. Erwinia chrysanthemi is a broad host range pathogen which produces soft rot symptoms due to a large production of pectinolytic enzymes. The strains of these two pathogens (respectively 1430 for E. amylovora and 3937 for E. chrysanthemi) we are studying in the laboratory are able to produce an hypersensitive response on tobacco leaves. Pathogenicity in E. amylovora is dependent on a cluster of genes encoding a type III secretion apparatus when E. chrysanthemi pathogenicity is dependent on a cluster of genes encoding a type II secretion apparatus. In E. amylovora an elicitor harpin protein secreted via the type II secretion apparatus has been isolated by Wei et al. .
Results and conclusions
In E. chrysanthemi we have isolated an elicitor protein which is a pectate lyase able, unlike the major pectate lyases (Pel a,b,c,d ande), to produce an hypersensitive response on tobacco leaves. The elicitor induces the production of phytoalexin and cellular death on tobacco cell cultures. This pectate lyase is secreted by the system II. We have shown that this elictor protein is a cleavage product of the pectate lyase Pel I by the proteases of E. chrysanthemi. In E. amylovora a protein, HrpW, different from the harpin is secreted by the type III secretion apparatus. Alignments between PelI and HrpW showed conserved "signatures" between the two proteins. Comparisons of the properties of these two proteins will be presented and discussed.
. Wei et al.1992 Science 257, 85-88