The potential effects of the forthcoming climate change include the rising of the average annual temperature and the accumulation of extreme weather events, like frequent and severe heatwaves, a phenomenon known as global warming. Temperature is an important environmental factor affecting almost all aspects of growth and development in plants. The grapevine (Vitis spp.) is quite sensitive to extreme temperatures. Over the current century, temperatures are projected to continue rising with negative impacts on viticulture. These consequences range from short-term effects on wine quality to long-term issues such as the suitability of certain varieties and the sustainability of viticulture in traditional wine regions. Many viticultural zones, particularly in Mediterranean climate regions, may not be suitable for growing winegrapes in the near future unless we develop heat-stress-adapted genotypes or identify and exploit stress-tolerant germplasm. Grapevines, like other plants, have developed strategies to maintain homeostasis and cope with high-temperature stress. These mechanisms include physiological adaptations and activation of signaling pathways and gene regulatory networks governing heat stress response and acquisition of thermotolerance. Here, we review the major impacts of global warming on grape phenology and viticulture and focus on the physiological and molecular responses of the grapevine to heat stress.

Epigenetics refers to dynamic chemical modifications to the genome that can perpetuate gene activity without changes in the DNA sequence. Epigenetic mechanisms play important roles in growth and development. They may also drive plant adaptation to adverse environmental conditions by buffering environmental variation. Grapevine is an important perennial fruit crop cultivated worldwide, but mostly in temperate zones with hot and dry summers. The decrease in rainfall and the rise in temperature due to climate change, along with the expansion of pests and diseases, constitute serious threats to the sustainability of winegrowing. Ongoing research shows that epigenetic modifications are key regulators of important grapevine developmental processes, including berry growth and ripening. Variations in epigenetic modifications driven by genotype–environment interplay may also lead to novel phenotypes in response to environmental cues, a phenomenon called phenotypic plasticity. Here, we summarize the recent advances in the emerging field of grapevine epigenetics. We primarily highlight the impact of epigenetics to grapevine stress responses and acquisition of stress tolerance. We further discuss how epigenetics may affect winegrowing and also shape the quality of wine.

This study investigates the impact of climate change on key physiological parameters of Greek indigenous grapevine cultivars (Savvatiano, Muscat, Assyrtiko, Mavrodafni, Moschofilero, and Agiorgitiko), using Sauvignon blanc and Merlot as benchmarks. The aim was to identify genotypes with higher photosynthetic dynamics and water use efficiency (WUE) under heat stress and to examine the role of CO₂ enrichment in modulating these responses. Gas exchange measurements showed that short-term exposure to elevated CO₂ (e[CO₂]) (i.e., 700 ppm) enhanced photosynthesis by 37–64%, 77–89%, and 18–68% under control, moderate, and severe heat-stress regimes (23, 35, and 40 °C), respectively. CO₂ enrichment also improved WUE by 61–122%, 96–138%, and 11–63%, with the greatest benefits at 30–33 °C, depending on genotype. Cultivars with strong CO₂-saturated photosynthetic capacity and small stomata, such as Sauvignon blanc and Mavrodafni, showed greater photosynthetic stimulation and WUE improvement from CO₂ elevation. Stomatal traits influenced photosynthesis under ambient CO₂ (a[CO₂]) but not under e[CO₂]. Of the white varieties examined, Sauvignon blanc and Savvatiano showed the best performance under combined e[CO₂] and heat stress, while Assyrtiko and Muscat adapted better to high temperatures at a[CO₂]. Among red cultivars, Mavrodafni showed the highest photosynthetic efficiency at both CO₂ conditions, even under heat stress. The present findings indicate that grapevine varieties exhibit differential responses to elevated temperature and CO₂ levels. A comprehensive understanding of grapevine responses to stress conditions is therefore essential for the selection of cultivars with enhanced adaptation to climate change.

Entomopathogenic fungi (EPF) are substantial biocontrol agents reducing the populations of economically important pests in numerous crops. Recent findings indicate that their role in agroecosystems is more complex and extends to affecting plant physiology and growth. This study examined the effects of Beauveria bassiana and Isaria fumosorosea, as well as Salicylic acid (SA), on physiological parameters of grapevine (Vitis vinifera cv. Sauvignon Blanc). Additionally, the impact of SA on spore germination and pathogenicity of EPF against larvae of the European grapevine moth (Lobesia botrana) was tested. Foliar application of EPF was found to increase the electron transport rate (ETR) from PSII to PSI, indicating higher photosynthetic activity compared to control plants. EPF also elevated the transpiration rate (E) and stomatal conductance (gs). In contrast, SA treatments decreased E and gs, while the high dose (10 mM) exhibited reduced Fv/Fm value, accompanied by phytotoxic spots on leaves. Spore germination of both fungi was significantly reduced only by the SA concentration of 2 mM, while 0.5 and 1 mM did not affect germination. Combination EPF and SA treatments presented the highest larval mortality of L. botrana (87.5% at 28 °C and 77.5% at 24 °C for B. bassiana and I. fumosorosea, respectively). However, SA reduced larval mycosis in most cases. Overall, the results suggest that EPF and SA can be co-applied and included in vineyard integrated strategies to support grapevine health.

This study investigates the effects of rising temperatures on photosynthetic efficiency and stress tolerance in major Greek grapevine cultivars by using Sauvignon Blanc and Merlot as references. Muscat and Assyrtiko displayed the most heat-tolerant photosynthetic apparatus among the white cultivars, while Mavrodafni was the most heat-tolerant among the red ones, by effectively managing excess light energy. Sauvignon Blanc, although exhibiting heat susceptibility, maintained high photosystem II (PSII) functionality under heat stress by activating photoprotective mechanisms. Savvatiano and Agiorgitiko were more vulnerable to photo-oxidative stress above 35 °C, while Agiorgitiko maintained a functional photosynthetic apparatus, even at 40 °C, by shifting to a more photoprotective strategy. In contrast, Merlot, despite its resistance to photo-oxidative stress, lacked photoprotective investment, resulting in suppressed PSII under heat stress. Moschofilero was the most susceptible cultivar to photo-oxidative stress. Leaf morphological traits also contributed to heat stress tolerance, with smaller, thicker leaves facilitating thermoregulation. The present results provide important insights into specific responses to heat stress of major Greek grapevine cultivars. This knowledge may aid in selecting heat-tolerant genotypes and optimizing vineyard site selection, thereby enhancing the sustainability and climate resilience of viticulture.

This study investigates the effects of rising temperatures on photosynthetic efficiency and stress tolerance in major Greek grapevine cultivars (Savvatiano, Muscat, Assyrtiko, Mavrodafni, Moschofilero, and Agiorgitiko), using Sauvignon Blanc and Merlot as ref-erence varieties. The primary aim was to identify heat tolerant genotypes suitable for cultivation in warm regions with high solar radiation. Another objective was to indicate shade-tolerant cultivars that could benefit from canopy shading techniques, contributing to broader climate adaptation strategies in viticulture. Muscat and Assyrtiko displayed the most heat-tolerant photosynthetic apparatus among white cultivars, while Mavrodafni was the most heat-tolerant among the red ones, by effectively managing excess light energy. Sauvignon Blanc although exhibiting heat susceptibility, it maintained high PSII functionality under heat stress by activating photoprotective mechanisms. Temperatures above 35 °C increased grapevine’s susceptibility to strong light, thereby intensifying photooxidative stress. Savvatiano and Agiorgitiko were more vulnerable to photooxi-dative stress above 35°C, though Agiorgitiko maintained a functional photosynthetic apparatus even at 40°C by shifting to a more photoprotective strategy. In contrast, Merlot, despite its resistance to photooxidative stress, lacked photoprotective investment, re-sulting in suppressed PSII under heat stress. Moschofilero was the most susceptible cul-tivar to photooxidative stress. Leaf morphological traits contributed to heat and light stress tolerance, with smaller, thicker leaves facilitating thermoregulation. Taken together, Merlot, Mavrodafni, Sauvignon Blanc, and Assyrtiko are recommended for high-altitude cultivation due to their high tolerance to light. Conversely, Savvatiano, Moschofilero, and Agiorgitiko were better suited to lower light conditions, favoring higher latitudes and shading practices under heat stress. The present results provide important insights into cultivar-specific responses to heat and light stresses, presenting for the first time the respective tolerances of major Greek cultivars. This knowledge is essential for selecting heat-tolerant genotypes, optimizing vineyard site selection and management strategies, thereby supporting the sustainability and climate resilience of viticulture.