Recovery of Vitis vinifera L. cv. ‘Kékfrankos’ from ‘bois noir’ disease

Abstract

AbstractInvestigation of diseases caused by phytoplasmas, a group of cell-wall-less gram-positive bacteria has received significant attention in plant pathology. Grapevine is a host of two, genetically distinct phytoplasmas: Line Flavescence dorée (FD) phytoplasma associated to ‘flavescence dorée’ and ‘Candidatus Phytoplasma solani’ responsible for ‘bois noir’ (BN) disease. In the current study, we focused on BN diseased grapevines (Vitis vinifera L. cv. ‘Kékfrankos’), measured their photosynthetic performance and leaf hydrogen peroxide (H2O2) concentration. The latter is generally considered as a key molecule in the process of ‘recovery’ which is a spontaneous and unpredictable long-term remission of disease symptoms. This phenomenon also occurred during the time of our experiment. Infection resulted in reduced gas exchange performance and maximum quantum efficiency of PSII with an increased regulated non-photochemical quenching of PSII and H2O2 concentration. Changes in gas exchange seem to be a systemic response, while reduced photochemistry is a local response to ‘Ca. P. solani’ infection. H2O2 accumulation in BN phytoplasma infected plants, unlike in FD disease, was found to be a typical response to the appearance of a biotic stressor.