Involvement of plasma membrane peroxidases and oxylipin pathway in the recovery from phytoplasma disease in apple (Malus domestica)

• Published in: Physiologia plantarum Vol. 148; no. 2; pp. 200 - 213
• Main Authors: Patui, Sonia, Bertolini, Alberto, Clincon, Luisa, Ermacora, Paolo, Braidot, Enrico, Vianello, Angelo, Zancani, Marco
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-06-2013; Blackwell; Wiley Subscription Services, Inc
• Subjects: Aldehyde-Lyases - metabolism; Apples; Bacterial plant pathogens; Biological and medical sciences; Cell Membrane - enzymology; Chlorophyll - metabolism; Cinnamates - analysis; Cinnamates - metabolism; Cyclopentanes - analysis; Cyclopentanes - metabolism; Cytochrome P-450 Enzyme System - metabolism; Fundamental and applied biological sciences. Psychology; Hydrogen Peroxide - metabolism; Hydrogen-Ion Concentration; Lipoxygenase - metabolism; Malus; Malus - enzymology; Malus - genetics; Malus - immunology; Malus - physiology; Malus domestica; Oxylipins - analysis; Oxylipins - metabolism; Peroxidases - genetics; Peroxidases - metabolism; Phenylalanine Ammonia-Lyase - metabolism; Phytopathology. Animal pests. Plant and forest protection; Phytoplasma - physiology; Plant Diseases - immunology; Plant Growth Regulators - analysis; Plant Growth Regulators - metabolism; Plant Leaves - enzymology; Plant Leaves - genetics; Plant Leaves - immunology; Plant Leaves - physiology; Plant physiology and development; Plant Proteins - genetics; Plant Proteins - metabolism; Salicylic Acid - analysis; Salicylic Acid - metabolism; Plant pathogen; Enzyme; Rosaceae; Malus domestica; Recovery; Oxylipin; Mollicutes; Peroxidases; Plant physiology; Dicotyledones; Angiospermae; Plasma membrane; Bacteria; Spermatophyta; Fruit tree; Oxidoreductases; Phytoplasma
• ISSN: 0031-9317; 1399-3054
• DOI: 10.1111/j.1399-3054.2012.01708.x

Apple trees (Malus domestica Borkh.) may be affected by apple proliferation (AP), caused by ‘Candidatus Phytoplasma mali’. Some plants can spontaneously recover from the disease, which implies the disappearance of symptoms through a phenomenon known as recovery. In this article it is shown that NAD(P)H peroxidases of leaf plasma membrane‐enriched fractions exhibited a higher activity in samples from both AP‐diseased and recovered plants. In addition, an increase in endogenous SA was characteristic of the symptomatic plants, since its content increased in samples obtained from diseased apple trees. In agreement, phenylalanine ammonia lyase (PAL) activity, a key enzyme of the phenylpropanoid pathway, was increased too. Jasmonic acid (JA) increased only during recovery, in a phase subsequent to the pathological state, and in concomitance to a decline of salicylic acid (SA). Oxylipin pathway, responsible for JA synthesis, was not induced during the development of AP‐disease, but it appeared to be stimulated when the recovery occurred. Accordingly, lipoxygenase (LOX) activity, detected in plasma membrane‐enriched fractions, showed an increase in apple leaves obtained from recovered plants. This enhancement was paralleled by an increase of hydroperoxide lyase (HPL) activity, detected in leaf microsomes, albeit the latter enzyme was activated in either the disease or recovery conditions. Hence, a reciprocal antagonism between SA‐ and JA‐pathways could be suggested as an effective mechanism by which apple plants react to phytoplasma invasions, thereby providing a suitable defense response leading to the establishment of the recovery phenomenon.