Oxidative effects in uninfected tissue in leaves of French bean (Phaseolus vulgaris) containing soft rots caused by Botrytis cinerea

Abstract

Several markers of oxidative processes have been measured in leaves of Phaseolus vulgaris infected with Botrytis cinerea, with the specific objective of investigating changes induced by this necrotrophic pathogen in tissue remote from the lesion. There was a progressive decrease with time in the contents of ascorbic acid (AA) in apparently healthy tissues from infected plants and non-inoculated plants grown under identical high-humidity conditions (abiotically stressed controls), and for periods >48 h this decrease was greater in the infected plants. This decline in AA content was accompanied by an elevation in the intensity of the electron paramagnetic resonance (EPR) signal from adducts of the spin trap α-(4-pyridyl-1-oxide)-N-t-butylnitrone (POBN), a destabilisation of the (monodehydro) ascorbate radical (Asc · ) signal in the presence of POBN, and an increase in the ratio of Asc · to AA in samples studied in the absence of the spin trap. These results are consistent with a shift in redox status to more oxidising conditions in apparently healthy tissue of infected plants and indicate the prevalence of chemical processes that are distinctly different from those in uninfected plants. However, no differences in lipid peroxidation products or the single-peak free radical and Fe(III) (g = 4.27) EPR signals were observed between these tissues distant from the lesions and those from abiotically stressed controls. In addition, the pathogen-derived sesquiterpene toxin botrydial and a second Mn(II) EPR signal, both of which are associated with Botrytis infection, were not detected in these 'apparently healthy' tissues.

Formation of paramagnetic products in leaves of wheat (Triticum aestivum) as a result of ozone‐induced stress

“…This is perhaps not surprising because of the large numbers of molecules in biological systems that are capable of participating in free radical reactions. Many scientists have reported the formation of the ascorbate radical (with a characteristic doublet spectrum having g = 2.0053, a ( 1 H) = 0.18 mT) in physically damaged and abiotically stressed tissue (see eg Refs 31 and 33). This signal could not be identified in the present work, because the broader linewidths of rigid‐limit spectra render the 1 H hyperfine structure unobservable.…”

Botrytis cinerea: the cause of grey mould disease

“…Histochemical staining in Botrytis ‐infected Arabidopsis leaves revealed that the oxidative burst in a compatible interaction comprises the simultaneous production of hydrogen peroxide and nitric oxide, as well as the formation of proteolytic, autophagosome‐like vesicles at the host–pathogen interface (van Baarlen et al ., 2007). B. cinerea infection leads to the accumulation of free radicals, both at the host–pathogen interface and at some distance from the invading hyphae (Muckenschnabel et al ., 2001a, 2003) culminating in lipid peroxidation (Deighton et al ., 1999; Muckenschnabel et al ., 2001b, 2002) and depletion of antioxidants (Muckenschnabel et al ., 2002). Altogether, these oxidative processes cause massive perturbation of the redox status in and around the infected tissue, thereby promoting disease progress (Lyon et al ., 2004).…”

Functional analysis of H2O2‐generating systems in Botrytis cinerea: the major Cu‐Zn‐superoxide dismutase (BCSOD1) contributes to virulence on French bean, whereas a glucose oxidase (BCGOD1) is dispensable

“…It has recently been shown that B. cinerea produces ROS in axenic culture and in planta : cytochemical analysis showed the presence of in hyphal tips and H 2 O 2 generation in and around the penetrated cell wall (Tenberge et al ., 2002). There is other clear evidence for ROS and the involvement of other markers of oxidative stress in tissues attacked by B. cinerea (Deighton et al ., 1999; Muckenschnabel et al ., 2001a,b, 2002, 2003).…”