terclim by ICS banner
IVES 9 IVES Conference Series 9 GiESCO 9 GiESCO 2023 9 Grapevine responses to red blotch disease – a structural-functional perspective of symptomatology development and fruit quality

Grapevine responses to red blotch disease – a structural-functional perspective of symptomatology development and fruit quality


Context and purpose of the study – Red Blotch disease caused by Grapevine red blotch-associated virus (GRBaV) is a severe  concern to grape growers and winemakers in major grape-growing regions worldwide. One key aspect of all viruses, including Red Blotch, is their intimate association with cell components and anomalous structures following infection. Therefore, the objective of this study was to analyze symptomatology, vine function, fruit quality and ultrastructure of various tissues and document the relationship of ultrastructural cytopathology with the GRBaV infection in Pinot Noir and Merlot employing various microscopy techniques. Such knowledge is fundamental to understanding the progression and the mechanisms by which the virus causes the infection, and designing strategies to control its spread in vineyards.

Material and methods – During the growing season, vine samples were collected from vineyards with a history of Red Blotch (Pinot Noir and Merlot) located in the states of Washington and Oregon. Starting at flowering, shoots (leaf and stem tissues) were sampled for microscopy analysis. These samples were used to determine the structure and functionality of the vascular strands (xylem and phloem) using callose-specific dye, aniline blue, and various microscopy techniques. At harvest, fruits were sampled to compare primary and secondary metabolites between healthy and infected vines.

Results – The infected vines exhibited typical red blotches in leaves with pinkish-red-colored veins without rolling off the margins at the onset of ripening. The infected vines developed clusters of hens and chickens and altered seed morphology.  Conversely, the healthy seeds were pyriform with a distinct beak. The infection significantly altered the primary and secondary metabolites desired for making wine. Since post-veraison berry development and ripening rely on phloem influx, the altered metabolism was indicative of a disruption of the phloem pathway either in the source leaf or in the berries. While the infected vines maintained the primary leaf anatomical organization, the chloroplast underwent significant ultrastructural changes ranging from the complete dismantling of the chloroplasts to massive accumulation of starch and plastoglobuli development in addition to tannins in the cytoplasm. The study demonstrated that structural integrity is a key to maintaining the normal metabolism of the grapevine, providing new insights into implementing innovative approaches for Red Blotch disease management.


Publication date: June 21, 2023

Issue: GiESCO 2023

Type: Article


Bhaskar BONDADA1, Bailey HALLWACHS1, Marc FUCHS2, Sadanand DHEKNEY3, Benham KHATABI3, Alexander LEVIN4, Patricia SKINKIS5

1Washington State University, Wine Science Center, 2710 Crimson Way, Richland, WA 99354, USA
2Cornell University, Section of Plant Pathology, Ithaca, NY 14853, USA
3University of Maryland Eastern Shore Princess Anne, MD 21853, USA
4Oregon State University, Southern Oregon Research and Extension Center, Central Point, OR 97502, USA
5Oregon State University, Corvallis, Oregon, 97331, USA

Contact the author*


callose, chloroplast, grapevine, plasmodesmata, red blotch, sieve tubes, tylosis, xylem


GiESCO | GIESCO 2023 | IVES Conference Series


Related articles…

An excessive leaf-fruit ratio reduces the yeast assimilable nitrogen in the must

Yeast assimilable nitrogen (YAN) in the grape must is a key variable for wine quality as a source of aroma precursors. In a situation of YAN deficiency, a foliar urea application upon the vine at veraison enhances YAN concentration and facilitates must fermentation. In 2013, Agroscope investigated the impact of leaf-fruit ratio on the nitrogen (N) assimilation and partitioning in grapevine Vitis vinifera cv. Chasselas following foliar-urea application with the aim of improving its efficiency on the YAN concentration.

Extraction of polyphenols from grape marc by supercritical fluid extraction (SFE) and evaluation of their ‘bioavailability’ as dietary supplements

In the winemaking process, several compounds that remain in the grape skins and seeds after the fermentation stage are bioactive-compounds (substances with potential beneficial effects on health) that can be extracted in order to recovery valuable substances with a high commercial value for the cosmetic, food (nutraceuticals) and pharmaceutical industries. The skins contain significant amounts of bioactive substances such as tannins (16-27%) and other polyphenolic compounds (2-6.5%) in particular, catechins, anthocyanins, proanthocyanins, quercetin , ellagic acid and resveratrol.

The impacts of frozen material-other-than-grapes (MOG) on aroma compounds of red wine varieties

An undesirable note called “floral taint” has been observed in red wines by winemakers in the Niagara region caused by large volumes of frozen leaves and petioles [materials-other-than-grapes (MOG)] introduced during mechanical harvest and subsequent winemaking late in the season. The volatiles, which we hypothesized are responsible, are primarily terpenes, norisoprenoids, and specific esters in frozen leaves and petioles. The purpose of this study was to investigate the volatile compounds which may cause the floral taint problem and explore how much of them (thresholds) may lead to the problem. Also, the glycosidic precursors of some of these compounds were analyzed to see the changes happening during frost events.

Aromatic profile of six different clones of Chardonnay grape berries in Minas Gerais (Brazil)

Aromas are one of the key points in food analysis since they are related to character, quality and consequently consumer acceptance. It is not different in the winery industry, where the aromatic profile is a combination of viticultural and oenological practices. Based on the development of more aromatic clones and on the potential to produce sparkling wines at Caldas, in the southern region of Minas Gerais (Brazil) (21°55´S and 46°23´W, altitude 1,100m), the aim of this work was the determination of volatile compounds in six different clones of Chardonnay grape berries to better understand which compounds add bouquet to the wine, and additionally comprehend the impacts of the edaphoclimatic and annual conditions on the improvement of grape-growing and winemaking practices.

Improving stilbenes in vitis Labrusca L. Grapes through methyl jasmonate applications

Grapes (Vitis sp.) are considered a major source of phenolic compounds such as flavonols, anthocyanins and stilbenes. Studies related to the beneficial effects of these compounds on health have encouraged research aimed at increasing their concentration in fruits. On this behalf, several plant growth regulators such as jasmonic acid and its volatile ester, methyl-jasmonate (MeJa), have demonstrated promising results in many fruits. However, Brazilian subtropical climate might interfere on treatment response. The present study aims to evaluate the application of MeJa in the pre-harvest period in Concord and Isabel Precoce grapes (Vitis labrusca L.).