Pathogen Profile #5

Hello Robigalia Reader, welcome back to another week of Robigalia, delivering the latest in plant pathology directly to your inboxes. Today’s newsletter is all about wine!

In August after attending the International Congress of Plant Pathology in Lyon I took a detour into the Friuli DOC region of Northern Italy. This picturesque area is predominantly known for its white wine production and boasts a rich variety of native grape cultivars, including Friulano, Verduzzo, Ribolla Gialla, Refosco, Picolit and Pignolo. The region also hosts popular introduced favorites such as Pinot Grigio and Prosecco. However, with such a diverse array of grapevines concentrated in one place, it becomes prime real estate for pests and pathogens to thrive.

Among the residents of this viticultural haven is the Grapevine Pinot Gris Virus (GPGV). First characterised in 2012 in the vineyards of northern Italy, GPGV is associated with grapevine leaf mottling and deformation disease (GLMD). This positive-sense single stranded RNA virus belongs to the genus Trichovirus within the family Betaflexiviridae. It colonises the plant’s vascular system, resulting in symptoms such as delayed bud break, leaf mottling, deformation, and shortened internodes. Recent studies have reported yield losses of up to 80% in severely affected vineyards.

Since its initial detection, GPGV has spread rapidly across the globe, being reported in most grape-growing countries across Europe, Asia, the Americas, The Middle East and even Australia. This global spread is likely the result of the viruses ability to spread through infected propagation material. Once established, vectors such as grape leaf bud-blister mites (Colomerus vitis) facilitate its transmission within vineyards.

The impact of GPGV extends far beyond individual vineyards. The economic losses associated with reduced yields, increased management costs, and potential quarantine measures can be substantial for the wine industry. The virus's spread also threatens the biodiversity of wild grapevine species and their associated ecosystems. These wild plants can also act as reservoirs for viruses such as GPGV.

Researchers and industry stakeholders are actively combatting GPGV. Strategies include selecting vector-resistant grapevine cultivars and implementing strict biosecurity measures to prevent the spread of infected material. Additionally, ongoing research aims to better understand the virus' biology, origins and evolution, transmission mechanisms, and potential interactions with other grapevine pathogens.

If you’re interested in reading more about GPGV, I’ve summarised a few articles below.

Grapevine Pinot gris Virus papers

The genetic variability of grapevine Pinot gris virus (GPGV) in Australia

• This study investigates GPGV's genetic diversity, introduction, and spread in Australia. It suggests GPGV was introduced to Australia through infected planting material, likely from Europe and local transmission is being facilitated by grape leaf bud-blister mites and the movement of infected planting material.

Grapevine Pinot Gris Virus Is Present in Different Non-Vitis Hosts

• The research demonstrates that GPGV can infect a variety of plant species beyond grapevines, emphasising the need for comprehensive virus management strategies that account for alternative hosts.

Grapevine Pinot gris virus in Germany: From where did the virus come, and when?

• This study provides insights into the origin, genetic diversity, and historical spread of GPGV. The study concluded that GPGV likely originated in North-east Asia, particularly in wild and cultivated Vitis species such as Vitis coignetiae.

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Until next week,

Alyssa