Application of fluorimetric indices in Vermentino plants affected by GPGV

Grapevine Pinot Gris virus (GPGV), a single-stranded RNA virus classified under the Trichovirus, infects grapevines, manifesting symptoms such as growth arrest, chlorotic mottling, and leaf deformation. Typically, when the viral infection is active, symptoms manifest in late spring, facilitating the visual identification of symptomatic and asymptomatic vines, even if there may also be latent forms. This visual classification is often detected through laboratory tests, such as the polymerase chain reaction prevented by reverse transcriptase as RNA virus (RT-PCR). This work focused on field monitoring, using an alternative method for detect GPGV in a Vermentino vineyard in Olmedo (Italy). A proximal fluorescence sensor was employed as a non-destructive tool to assess leaf physiological activities. In the summer of 2021, 50 vines were sampled and classified in two groups N (Negative) or P (Positive) after laboratory assays RT-PCR: 20 vines were classified as N, and 30 as P. Before collecting the samples, the plants were analyzed with a proximal fluorimetric sensor, which utilized indices related to leaf physiological characteristics. The statistical analysis, performed by ANOVA, revealed a significant difference between N and P vines, particularly in the anthocyanin FER_RG index. From the analysis, the FER_RG index was superior in P plants, indicating a higher anthocyanin density than in asymptomatic plants, and thus estimating a lower chlorophyll content. This suggests the potential of proximal fluorescence sensing as a valuable tool for early GPGV detection in grapevines, offering a non-destructive and efficient tool of assessing plant health.