Hydrogen peroxide localization and antioxidant status in the recovery of apricot plants from European Stone Fruit Yellows

Abstract

Hydrogen peroxide (H2O2) localization and roles of peroxidases, malondialdehyde and reduced glutathione\ud were compared in leaves of apricot (Prunus armeniaca) plants: asymptomatic, European Stone Fruits\ud Yellows (ESFY)-symptomatic and recovered. Nested PCR analysis revealed that ‘Candidatus Phytoplasma\ud prunorum’, is present in asymptomatic, symptomatic and recovered apricot trees, confirming previous\ud observations on this species, in which recovery does not seem to be related to the disappearance of\ud phytoplasma from the plant.\ud H2O2 was detected cytochemically by its reaction with cerium chloride, which produces electron-dense\ud deposits of cerium perhydroxides. H2O2 was present in the plasmalemma of the phloem cells of recovered\ud apricot plant leaves, but not in the asymptomatic or symptomatic material. Furthermore, by labelling\ud apricot leaf tissues with diaminobenzidine DAB, no differences were found in the localization of peroxidases.\ud Protein content in asymptomatic, symptomatic and recovered leaves was not significantly different from\ud one another. In contrast, guaiacol peroxidase activity had the following trend: symptomatic\ud > recovered > asymptomatic, whereas reduced glutathione content followed the opposite trend:\ud asymptomatic > recovered > symptomatic. Moreover, no differences were observed in malondialdehyde\ud concentrations between asymptomatic, symptomatic and recovered leaves. The overall results suggest that\ud H2O2 and related metabolites and enzymes appear to be involved in lessening both pathogen virulence and\ud disease symptom expression in ESFY-infected apricot plants

Salicylic Acid Protects Potato Plants-from Phytoplasma-associated Stress and Improves Tuber Photosynthate Assimilation

“…1). H 2 O 2 overproduction occurred in phytoplasma-infected apple and apricot trees (Musetti et al 2004(Musetti et al , 2005. In the present study, the absence of H 2 O 2 overproduction in phytoplasma-free plants likely occurred because they lacked pathogen-induced oxidative stress.…”

Phytoplasmas and Phytoplasma Diseases: A Severe Threat to Agriculture

“…Because of the wide array of symptoms expressed by diseased plants, nutrient depletion is probably not restricted to sugars, but also includes other compounds. A reduction in the concentration of photosynthetic pigments [137] and of total soluble proteins [137]- [139], as well as alterations in the hormone balance [135] [140], amino-acid transport [134] and the occurrence of folate and endopetidase gene homologues in phytoplasma genomes [141] were described as potentially affecting host plants infected with different phytoplasmas.…”

Role of lipoxygenase and allene oxide synthase in wound-inducible defense response of pea

“…Lots of reports demonstrated that wounding and applied JA could induce oxidative stress [23], which was also observed in the wounded pea seedlings (Fig. 5).…”