Lipid peroxidation and the oxidative burst associated with infection of Capsicum annuum by Botrytis cinerea

Abstract

Summary A combination of electron paramagnetic resonance (EPR) spectroscopy and analytical chemistry has been used to study the changes in free radical content, transition metal ion status and lipid peroxidation following inoculation of fruits of sweet pepper (Capsicum annuum) with Botrytis cinerea. EPR detected a high concentration of an unidentified free radical associated with the spreading lesion that extends into the surrounding, healthy tissues. In addition, the EPR‐detectable iron(III) was highest at the centre of the lesion, again displaying a gradient out into the surrounding tissues. Analyses for aldehydic products of lipid peroxidation were performed to assess the accumulation and potential of these compounds to contribute to the cell death associated with necrotrophic pathogens. In contrast to the spectrum of aldehydes typically observed within peroxidized biological samples, no accumulation of malondialdehyde nor n‐hexanal was observed. Instead, high levels of two hydroxyalkenals (4‐hydroxy‐2‐hexenal and 4‐hydroxy‐2‐nonenal) were detected at concentra‐ tions up to 4000 and 20 000 pmol g− 1, respectively, at the host–pathogen interface. These results are discussed in terms of the likely mechanisms of formation of these aldehydes.

Expression and Functional Analyses of the Plastid Lipid-Associated Protein CHRC Suggest Its Role in Chromoplastogenesis and Stress

“…There is now evidence (Urbanek et al, 1996;Von Tiedemann, 1997) that the generation of active oxygen species assists in the colonization of plant tissues by necrotrophic organisms, such as B. cinerea. One of the most obvious and consistent effects of B. cinerea infection is a large increase in the electron paramagnetic resonance free-radical signal in rotted tissue compared to controls; similar results have been obtained with leaves and fruit (Deighton et al, 1999;Muckenschnabel et al, 2001). LeCHRC, similar to other PAPs, may assist in contending with the oxidative stress: Its suppression may lower the plant's ability to withstand the oxidative stress associated with B. cinerea attack, hence leading to increased susceptibility to infection.…”

Rice Blast Fungus (Magnaporthe oryzae) Infects Arabidopsis via a Mechanism Distinct from That Required for the Infection of Rice

“…A previous report indicated that necrotrophic pathogens use oxidative bursts to invade and destroy plant tissues (Deighton et al, 1999). The 9,12-octadecadienoic acid may be a precursor of biologically active oxylipins in plants with JA as a terminal signal (Blechert et al, 1995).…”

The Membrane-Anchored BOTRYTIS-INDUCED KINASE1 Plays Distinct Roles in Arabidopsis Resistance to Necrotrophic and Biotrophic Pathogens

“…Whereas necrotrophic pathogens induce cell death in their hosts by secreting toxic substances into host tissue before and during colonization, biotrophic pathogens require living cells to complete their life cycle. The necrotroph Botrytis cinerea produces cell wall-degrading enzymes (Prins et al, 2000), toxic levels of reactive oxygen intermediates (Edlich et al, 1989;Deighton et al, 1999;Muckenschnabel et al, 2002), and toxins (Tiedemann, 1997;Colmenares et al, 2002) that result in the death and maceration of tissue, leading to plant decay. Evidence to date strongly suggests a limited role for SAR and gene-for-gene (race-specific) resistance against necrotrophic pathogens in Arabidopsis thaliana.…”