Involvement of a hypersensitive-like reaction in tolerance to fire blight in pear (pyrus communis L.)

Abstract

Infection by Erwinia amylovora, the causal agent of fire blight (FB) disease, induces in apple and pear host plants, the generation of reactive oxygen species (ROS). We analyzed at molecular level, the link between ROS production and susceptibility to bacterial infection. Gene expression time course showed that expression of chloroplast, mitochondrial and nuclear genes, whose transcription is redox-dependent, was down regulated or suppressed in tolerant cultivar, Harrow Sweet, in comparison with susceptible cultivar, Williams. Monitoring of oxidative burst by localization of hydrogen peroxide showed that oxidative burst was triggered faster in tolerant cultivar in response to infection. These results suggest that transcription of some redox-dependent genes of cytoplasmic organelles and nucleus, in the two cultivars, is regulated faster in the tolerant cultivar than in the susceptible one.

Keywords: Chloroplast, electron transport Chain, Erwinia amylovora, mitochondria, Pyrus communis, redox

African Journal of Biotechnology, Vol 13(28) 2840-2849