Abstract
Dark respiration (Rd) is a fundamental plant process used to gain biomass and maintain plant physiological activity. It accounts for the metabolization of a large share of the carbon fixed by photosynthesis. However, Rd during conditions of severe plant water stress is still poorly understood. The decrease in leaf transpiration increases temperature, one of the most important drivers of leaf Rd. On the other hand, water stress decreases the pool of leaf carbohydrates, which are the most important substrate for respiration. The aim of the present work was to determine the impact of water shortage on leaf Rd in grapevine and understand the driving factors in modulating leaf Rd response under plant water stress conditions. Water stressed vines had lower Rd as the water shortage severity increased. Rd was correlated with leaf temperature in well-watered vines. Instead, in water stressed vines, Rd correlated with leaf soluble sugars. The decrease of leaf Rd in water stressed vines was due to the decrease of leaf non-structural carbohydrate that, under water stress conditions, exerted a limiting effect on Rd.
Highlights
DOY, day of the year; gs, stomatal conductance; Ψpd, pre-dawn water potential; PPFD, photosynthetic photon flux density; Pn, net photosynthesis; Rd, dark respiration; RWC, relative water content; Tleaf, leaf temperature; water stressed (WS), water stress; WW, well-watered.Mitochondrial respiration is the controlled oxidation of reduced carbohydrates, producing CO2, reducing equivalents (NAD(P)H and FADH2) and resulting in respiratory O2 consumption and ATP production [1]
Drought stress and heat waves negatively impact several processes; plant growth is reduced during the early stages of water shortage [12], transpiration and photosynthesis is limited [13] and plant carbon partitioning to different organs is altered [14]
Our experiment demonstrated that the reduction of leaf Rd over Ψpd was related to the dynamic of Non-structural carbohydrates (NSC) content in the leaf, that decreased over the water stress period
Summary
DOY, day of the year; gs , stomatal conductance; Ψpd , pre-dawn water potential; PPFD, photosynthetic photon flux density; Pn , net photosynthesis; Rd , dark respiration; RWC, relative water content; Tleaf , leaf temperature; WS, water stress; WW, well-watered.Mitochondrial respiration ( referred to as dark respiration) is the controlled oxidation of reduced carbohydrates, producing CO2 , reducing equivalents (NAD(P)H and FADH2) and resulting in respiratory O2 consumption and ATP production [1]. Drought stress and heat waves negatively impact several processes; plant growth is reduced during the early stages of water shortage [12], transpiration and photosynthesis is limited [13] and plant carbon partitioning to different organs is altered [14]. Water stress increases leaf temperature due to a reduced leaf transpiration [16] and reduces the respiration substrate pool, due to a reduced photosynthetic assimilation [17]. This can cause Rd to be limited by different factors according to the level of water availability
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