Erwinia amylovora manipulates the expression of resistance-associated apple amaranthin-like lectin encoding genes

In a former work performed with susceptible apple plants (Malus domestica), it was demonstrated that the fire blight bacterium Erwinia amylovora is able to inhibit the production of a host amaranthin-like lectin that agglutinates bacterial cells in vitro by binding to surface microbial polysaccharides.
In this study, we analysed the ability of the bacterium to modulate the expression of the lectin encoding genes in the resistant apple genotype ‘Evereste’ and evaluated the bactericidal effect of the purified lectin on bacterial suspensions.
We showed that, in contrast to what we observed in a susceptible apple genotype, the bacteria is not able to repress in a type III secretion system-dependent manner the expression of the lectin encoding genes when infecting the resistant genotype ‘Evereste’. Moreover, although the purified apple lectin was able to agglutinate bacterial cells, it does not impair the bacterial capacity to multiply in vitro.
Altogether, these results confirm that apple lectins are plant defence proteins whose production is differentially modulated by Erwinia amylovora according to the susceptible status of the host genotype, but that these lectins are not bactericidal per se.

XXXI International Horticultural Congress (IHC2022): International Symposium on Sustainable Control of Pests and Diseases

E. Chavonet, A. Bodelot, M. Gaucher, E. Vergne, C. Heintz, R. Cournol, M.N. Brisset, A. Degrave

Malus domestica, fire blight, type 3 secretion system, plant defence, agglutinins

https://doi.org/10.17660/ActaHortic.2023.1378.54