engleski

Effect of flavescence dorée phytoplasma infection on physiological parameters of grapevine (Vitis vinifera) var. ‘Pinot noir’

Phytoplasmas, bacteria of genus ‘Candidatus Phytoplasma’, infect both plants and insects, which act as their vectors. They are pathogens of various agriculturally important plants, causing severe damage to crop. Phytoplasmas have been identified as causative agents of grapevine yellows (GY) diseases, which affect viticultural production worldwide. Two phytoplasmas have been linked to GY, one of which is the flavescence dorée phytoplasma (FDp, ribosomal group 16SrV), a quarantine pathogen in many countries. However, due to the inability to establish in vitro phytoplasma culture, phytoplasma research is still challenging. In this study, we collected symptomatic and asymptomatic leaves of grapevine (Vitis vinifera L.) var. ‘Pinot noir’ from a vineyard in central continental Croatia at three time points during the development of infection. Using a multiplex real time PCR assay, we confirmed the infection with FDp in symptomatic leaves. To assess the physiological response of grapevine to FDp infection, we used a plethora of spectrophotometric assays. Effect of FDp infection on photosynthetic pigment content in grapevine and level of proline and soluble sugars was analysed. Furthermore, the content of hydrogen peroxide, a reactive oxygen species (ROS), was assessed in sampled leaves, as well as the level of lipid peroxidation, an indicator of membrane damage. Results revealed an induction of ROS synthesis as well as the higher level of lipid peroxidation in leaves of infected plants, pointing to the occurrence of oxidative stress in infected plants. Induction of proline and sugar synthesis was also observed in infected plants, pointing to the activation of grapevine defence mechanisms against FDp infection. However, the biggest differences in the content between infected and uninfected leaves were observed for photosynthetic pigments, which point to a strong inhibition of photosynthetic processes in grapevine infected with FDp. Results expand the knowledge of the effect of phytoplasma infection on grapevine leaves physiology, as well as grapevine protective mechanisms against phytoplasma infection.

hydrogen peroxide, lipid peroxidation, photosynthetic pigments, proline, ROS, sugars

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