Effects of Grapevine leafroll‐associated virus 3 on the physiology in asymptomatic plants of Vitis vinifera

Abstract

Grapevine leafroll disease is one of the most important viral diseases of grapevine (Vitis vinifera) worldwide. Grapevine leafroll-associated virus 3 (GLRaV-3) is the most predominant virus species causing this disease. Therefore, it is important to identify GLRaV-3 effects, especially in plants which do not systematically show visual symptoms. In this study, effects of GLRaV-3 on grapevine physiology were evaluated in asymptomatic plants of Malvasía de Banyalbufar and Cabernet Sauvignon cvs. Absolute virus quantification was performed in order to determine the level of infection of the treatment. The net carbon dioxide (CO 2 ) assimilation (A N ) and electron transport rate (J flux ) were the main parameters affected by the virus. The A N reduction in infected plants was attributed to restrictions in CO 2 diffusion caused by anatomical leaf changes and a reduction of Rubisco activity. Those effects were more evident in Malvasia de Banyalbufar plants. The reduction of A N leads to a decrease in the total oxygen uptake rate by the activity of the cytochrome oxidase pathway, producing slight differences in plant growth. Therefore, even though no symptoms were expressed in the plants, the effects of the virus compromised the plant vital processes, showing the importance of early detection of the virus in order to fight against the infection.Closteroviridae family. In red varieties, symptoms of GLRaV-3 are easily identified, noticeable as dark-red, downward rolling leaves with green veins, but the infection is almost asymptomatic in white varieties. The difficulty in detecting virus can lead to rapid spread of virus-infected material through propagation. Diagnostic methods for the detection of grapevine viruses have been developed over the last few years. These methods include: biological indexing (Habili et al., 1992), enzyme-linked immunosorbent assay (ELISA) (Rowhani, 1992;Frosline et al., 1996;Rowhani et al., 1997) and nucleic acid-based methods, mainly PCR methods (Minafra et al.Grapevine leafroll-associated virus 3 effects on plant physiology R. Montero et al.

Dissecting interplays between Vitis vinifera L. and grapevine virus B (GVB) under field conditions

“…berries) and that the phloem is probably the main route of virus diffusion. Our results confirmed that GVB abundance can vary during the growing season, indicating that both climatic conditions and plant phenological stage play a key role in influencing virus movement within an infected vine and concentration, as indicated previously for other virus–grapevine genotype combinations (El Aou‐ouad et al., ; Gambino et al., ; Montero et al., ; Vega et al., ; Velasco et al., ). Of particular note, the GVB titre measured in ‘Albarossa’ berries was more than 1000 times higher than that in leaves collected at the end of the season.…”

“…The analysis of leaf physiological performances attested that net photosynthesis, stomatal conductance and substomatal CO 2 concentration were the main parameters affected by GVB, particularly at the end of the season. Nevertheless, GVB‐infected grapevines underwent a decrease in terms of physiological performance to a lesser extent than other grapevine–virus combinations (Guidoni et al., ; Mannini et al., ; Montero et al., ; Sampol et al., ). The overall picture of gas exchange measurements indicated a moderate metabolic, non‐stomatal, photosynthetic limitation in GVB‐infected plants in the absence of environmental and/or water limitation, in accordance with the results reported previously in GRSPaV‐infected grapevines (Gambino et al., ).…”

“…The overall picture of gas exchange measurements indicated a moderate metabolic, non‐stomatal, photosynthetic limitation in GVB‐infected plants in the absence of environmental and/or water limitation, in accordance with the results reported previously in GRSPaV‐infected grapevines (Gambino et al., ). Furthermore, the results revealed that infected plants experienced higher ci rates at the end of the season, probably because of the slow down of the Calvin cycle, resulting in a metabolic hindrance to CO 2 diffusion in the mesophyll (Montero et al., ; Sampol et al., ). Looking at the biochemistry of photosynthesis, the Rubisco content was higher in GVB‐infected plants, mainly at the end of August, consistent with the observations on the expression trends of the VvRubisco activase gene.…”

Predominance and Diversity of GLRaV-3 in Native Vines of Mediterranean Croatia

“…After GLRaV-3, the second and the third most abundant viruses in the present study were GRSPaV and GVA associated with the rugose wood complex disease. Confirming data from surveys carried out in the Mediterranean basin [ 26 , 27 ] as well as worldwide [ 28 , 29 ] GRSPaV was found in 81.69% of tested samples. However, although wide-spread, GRSPaV infection has no significant impact on growth and yields and potentially may be even beneficial to the grapevine host [ 30 ].…”

The Molecular Priming of Defense Responses is Differently Regulated in Grapevine Genotypes Following Elicitor Application against Powdery Mildew

“…Changes to photosynthesis and carbohydrate metabolism in different tissues also represent a basic physiological response of grapevine, not only in presence of PM attack [35,43,54] but also under other plant diseases [34,44,45]. The enhanced activity of grape invertase genes coupled with the increased accumulation of soluble sugars in infected leaves most likely causes a shift in the sink-source balance that progressively slows down the Calvin cycle, with consequent serious reduction of the plant assimilation rates [44][45][46]55]. Although carbohydrate metabolism is globally down-regulated by AcS-Mt treatment in our samples, other specific categories of carbohydrate metabolic genes, mostly involved in sugar-primed signaling processes, were highly activated.…”