Induction and regression of early boron deficiency in grapevine in hydroponics: macro- versus micro-scale symptomatology

With or Without You: Altered Plant Response to Boron-Deficiency in Hydroponically Grown Grapevines Infected by Grapevine Pinot Gris Virus Suggests a Relation Between Grapevine Leaf Mottling and Deformation Symptom Occurrence and Boron Plant Availability

“…Symptom similarity at macroscopical level is not confirmed at ultrastructural level. In fact, if GPGV did not significantly alter host histological and ultrastructural organization (beside the presence of ER-like deformed structures, see Tarquini et al, 2018Tarquini et al, , 2019b, conversely, B starvation led to profound changes at both histological and ultrastructural level (Ermacora et al, 2017).…”

“…Nevertheless, the mechanisms prompting GLMD symptom expression are still unclear. Since GMLD symptoms on grapevine resemble those induced by B-deficiency (Scott and Schrader, 1947;Christensen et al, 2006;Ermacora et al, 2017), we set up an experimental system where healthy and GPGV-infected Pinot gris grapevines were grown in controlled environmental conditions, with different B supplies (+B and −B). Both healthy and GPGV-infected plants grown in full nutrient conditions did not display any symptom until the end of the experiment.…”

“…Interestingly, the different epidemiological traits of GLMD hint at alterations in plant boron (B) nutrition. Among them, the capricious and discontinuous nature of GLMD symptoms during the growing season and between years, and variations in the type of alterations caused to leaf and shoot morphology in GLMD affected grapevines in the field (such as interveinal chlorosis of the older leaves, cupping and malformation of the young leaves, shortening of the apical internodes) reminded us of the typical B deficiency phenotype in grapevine (Scott and Schrader, 1947;Christensen et al, 2006;Osler et al, 2016;Ermacora et al, 2017). Plant roots take up B primarily as boric acid (B(OH) 3 ), a small, uncharged molecule that is relatively permeable across biological membranes (Dordas and Brown, 2000;Stangoulis et al, 2001).…”

The conundrum of the connection of grapevine Pinot gris virus with the grapevine leaf mottling and deformation syndrome

“…We hypothesize that GLMD symptoms could be primarily related to the activation and suppression of antiviral RNA silencing, which in turn is affected by the occurrence of mixed infections by distinct strains of the virus with variable virulence. Moreover, suppression of antiviral defence by GPGV CP may directly or indirectly interfere with unrelated physiological pathways, such as those mediating boron homoeostasis (Buoso et al, 2020; Ermacora et al, 2018; Kiss et al, 2021), further affecting symptom expression and severity (Senda, 2004). Unquestionably, further studies are necessary to clarify the picture.…”

“…The hypothesis of involvement of environmental factors such as mineral nutrition in this context has also been investigated. A role for boron homoeostasis in attenuation of GLMD symptoms has been suggested by Ermacora et al (2018) on the basis of boron-deficiencyassociated symptoms being present in virus-free grapevines grown in hydroponics. Later, Buoso et al (2020) investigated the effects of GPGV infection on boron acquisition and translocation machinery.…”