Boosting Grape Health with a Natural Plant Spray

David Palenski
20th January, 2024

Boosting Grape Health with a Natural Plant Spray

Wine grape (Vitis vinifera)

Photo adapted from: Christoph Moning / CC BY (Source)
Plants respond to environmental stresses, such as insect attack, by activating defense mechanisms. A key part of this response involves signaling molecules called jasmonates, which trigger changes in gene activity and the production of protective compounds[2]. These compounds can range from physical barriers to toxic substances for herbivores, or even alterations in the plant’s aroma. Understanding how plants activate these defenses is crucial for improving crop resilience and quality. Researchers at the University of Pisa[1] investigated how applying methyl jasmonate (MeJA), a signaling molecule mimicking insect damage, affects both grape berries and the leaves of grapevines. Previous work has shown that MeJA can increase aroma compounds in grapes[3] and trigger defense responses in bilberry plants, shifting resources away from growth and reproduction towards defense[4]. The aim of this study was to determine whether applying MeJA to leaves or directly to grape clusters had different effects, and to understand how these effects might be linked. The study involved applying a MeJA solution to either the leaves only, or the grape clusters only, of Sangiovese grapevines. A control group received no treatment. The researchers then measured various parameters, including gas exchange in the leaves (how much carbon dioxide the leaves take in and oxygen they release), leaf efficiency, and the levels of different compounds in the berries, particularly those contributing to aroma. The results showed that applying MeJA to the leaves had a distinct effect from applying it to the clusters. When applied to leaves, MeJA reduced leaf efficiency and stimulated senescence – essentially, it sped up the aging process of the leaves. However, this treatment did not directly affect the metabolism of the grape berries. This suggests that while leaves respond directly to MeJA, any effect on the berries is not a result of direct signaling from the leaves. Conversely, applying MeJA directly to the grape clusters significantly delayed berry ripening. This delay was accompanied by a substantial increase in the concentration of aroma compounds in the berries, particularly monoterpenes. Monoterpenes are a class of organic compounds responsible for many of the floral and citrusy aromas found in wine. The increase wasn’t just in the total amount of aroma, but specifically in glycosylated forms of these compounds – meaning they were attached to sugar molecules. This suggests a redirection of resources within the berry, channeling them towards the production of these volatile compounds. These findings build upon earlier research demonstrating that jasmonates play a critical role in plant defense[2]. The study also supports the idea that plants can strategically allocate resources, prioritizing defense over growth and reproduction when under perceived threat[4]. The observation that applying MeJA to leaves induced senescence is also consistent with the broader understanding of jasmonates as signaling molecules involved in plant development and stress responses. Interestingly, the study also sheds light on the ongoing debate about how water transport functions in developing grapes[5]. While the current study doesn’t directly address xylem function, the observed changes in berry metabolism and ripening suggest a complex interplay between resource allocation and physiological processes within the fruit. The delay in ripening caused by MeJA application implies a shift in how the berry utilizes its resources, potentially impacting water flow and nutrient distribution. The research highlights that the location of MeJA application is critical. Applying it to leaves triggers a localized stress response, while applying it to clusters directly impacts berry development and aroma production. This suggests that different signaling pathways are activated depending on where the jasmonate signal originates.

FruitsBiochemPlant Science

References

Main Study

1) Berry secondary metabolites and leaf physiological parameters are independently regulated by exogenous methyl jasmonate application in Sangiovese grapevines (Vitis vinifera L.).

Published 20th January, 2024

https://doi.org/10.1016/j.plaphy.2024.108378

Related Studies

2) Jasmonic Acid Signaling Pathway in Response to Abiotic Stresses in Plants.

https://doi.org/10.3390/ijms21020621

3) Effect of methyl jasmonate on the aroma of Sangiovese grapes and wines.

https://doi.org/10.1016/j.foodchem.2017.09.084

4) Transcriptional profiling of methyl jasmonate-induced defense responses in bilberry (Vaccinium myrtillus L.).

https://doi.org/10.1186/s12870-019-1650-0

5) The peripheral xylem of grapevine (Vitis vinifera). 1. Structural integrity in post-veraison berries.

https://doi.org/10.1093/jxb/ern060


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