Abstract
Rising temperature is among the most remarkably stressful phenomena induced by global climate changes with negative impacts on crop productivity and quality. It has been previously shown that volatiles belonging to the isoprenoid family can confer protection against abiotic stresses. In this work, two Vitis vinifera cv. ‘Chardonnay’ clones (SMA130 and INRA809) differing due to a mutation (S272P) of the DXS gene encoding for 1-deoxy-D-xylulose-5-phosphate (the first dedicated enzyme of the 2C-methyl-D-erythritol-4-phosphate (MEP) pathway) and involved in the regulation of isoprenoids biosynthesis were investigated in field trials and laboratory experiments. Leaf monoterpene emission, chlorophyll fluorescence and gas-exchange measurements were assessed over three seasons at different phenological stages and either carried out in in vivo or controlled conditions under contrasting temperatures. A significant (p < 0.001) increase in leaf monoterpene emission was observed in INRA809 when plants were experiencing high temperatures and over two experiments, while no differences were recorded for SMA130. Significant variation was observed for the rate of leaf CO2 assimilation under heat stress, with INRA809 maintaining higher photosynthetic rates and stomatal conductance values than SMA130 (p = 0.003) when leaf temperature increased above 30 °C. At the same time, the maximum photochemical quantum yield of PSII (Fv/Fm) was affected by heat stress in the non-emitting clone (SMA130), while the INRA809 showed a significant resilience of PSII under elevated temperature conditions. Consistent data were recorded between field seasons and temperature treatments in controlled environment conditions, suggesting a strong influence of monoterpene emission on heat tolerance under high temperatures. This work provides further insights on the photoprotective role of isoprenoids in heat-stressed Vitis vinifera, and additional studies should focus on unraveling the mechanisms underlying heat tolerance on the monoterpene-emitter grapevine clone.
Highlights
High-temperature stress is one of the main environmental conditions affecting crop physiology and productivity [1,2]
A significant (p < 0.001) increase in leaf monoterpene emission was observed in INRA809 when plants were experiencing high temperatures and over two experiments, while no differences were recorded for SMA® 130 clone (SMA130)
Fv /Fm values before and after HS when compared to INRA809 (p < 0.001), with the latter showing sustained Fv /Fm after heat stress compared to the relative control before the HS
Summary
High-temperature stress (heat stress, HS) is one of the main environmental conditions affecting crop physiology and productivity [1,2]. According to the fifth assessment report of the Intergovernmental Panel on Climate Change, further increases in annual temperatures are expected in the future [3]. The degree of heat stress damage in grapevine depends on both maximum diurnal temperature and the duration of daily HS, with significant physiological downregulation in days with prolonged. High temperatures can have direct harmful effects associated with physical damage to tissues or indirect effects linked with changes in plant metabolism [1,2]. One of the main consequences of HS often coupled with the presence of intense solar radiation is the excessive production of reactive oxygen species (ROS), which leads to oxidative stress [7]
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