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Lipids and oils determine the quality and industrial value of grape seeds. Studies with legume seeds demonstrated the influence of light on lipidmetabolismand its association with seed photosynthesis. Grape berry seeds are photosynthetically active till mature stage, but mostly during the green stage and veraison. The objective of this work was to compare the lipid profiles of seeds fromwhite grape berries (cv. Alvarinho) growing at two contrasting lightmicroclimates in the canopy (low and high light, LL and HL respectively), previously reported to have distinct photosynthetic competences. Berries were collected at three developmental stages (green, veraison and mature) and from both microclimates, and the seeds were analyzed for their lipid profiles in an untargeted manner using liquid chromatography coupled to high resolution mass spectrometry (LCMS). The seed lipid profiles differed greatly among berry developmental stages, and to a lesser extend between microclimates. The LL microclimate coincided with a higher relative levels of fatty acids specifically at mature stage, while the HL microclimate led to an up-regulation of ceramides at green stage and of triacylglycerols and glycerophospholipids at mature stage. The seed transcript levels of four key genes (VvΔCCase1, VvD9FAD, VvFAD6 and VvLOXO) involved in fatty acidmetabolism were analyzed using real-time qPCR. The lipoxygenase gene (VvLOXO) was down- and up-regulated by HL, as compared to LL, in seeds at green and veraison stages, respectively. These results suggest that seed photosynthesis may play distinct roles during seed growth and development, possibly by fueling different lipid pathways: at green stage mainly towards the accumulation of membrane-bound lipid species that are essential for cell growth and maintenance of the photosynthetic machinery itself; and at veraison and mature stages mainly towards storage lipids that contribute to the final quality of the grape seeds. [ABSTRACT FROM AUTHOR]

Lipids and oils determine the quality and industrial value of grape seeds. Studies with legume seeds demonstrated the influence of light on lipid metabolism and its association with seed photosynthesis. Grape berry seeds are photosynthetically active till mature stage, but mostly during the green stage and veraison. The objective of this work was to compare the lipid profiles of seeds from white grape berries (cv. Alvarinho) growing at two contrasting light microclimates in the canopy (low and high light, LL and HL respectively), previously reported to have distinct photosynthetic competences. Berries were collected at three developmental stages (green, veraison and mature) and from both microclimates, and the seeds were analyzed for their lipid profiles in an untargeted manner using liquid chromatography coupled to high resolution mass spectrometry (LCMS). The seed lipid profiles differed greatly among berry developmental stages, and to a lesser extend between microclimates. The LL microclimate coincided with a higher relative levels of fatty acids specifically at mature stage, while the HL microclimate led to an up-regulation of ceramides at green stage and of triacylglycerols and glycerophospholipids at mature stage. The seed transcript levels of four key genes (VvACCase1, VvΔ9FAD, VvFAD6 and VvLOXO) involved in fatty acid metabolism were analyzed using real-time qPCR. The lipoxygenase gene (VvLOXO) was down- and up-regulated by HL, as compared to LL, in seeds at green and veraison stages, respectively. These results suggest that seed photosynthesis may play distinct roles during seed growth and development, possibly by fueling different lipid pathways: at green stage mainly towards the accumulation of membrane-bound lipid species that are essential for cell growth and maintenance of the photosynthetic machinery itself; and at veraison and mature stages mainly towards storage lipids that contribute to the final quality of the grape seeds.

Viticulture practices that change the light distribution in the grapevine canopy can interfere with several physiological mechanisms, such as grape berry photosynthesis and other metabolic pathways, and consequently impact the berry biochemical composition, which is key to the final wine quality. We previously showed that the photosynthetic activity of exocarp and seed tissues from a white cultivar (Alvarinho) was in fact responsive to the light microclimate in the canopy (low and high light, LL and HL, respectively), and that these different light microclimates also led to distinct metabolite profiles, suggesting a berry tissue-specific interlink between photosynthesis and metabolism. In the present work, we analyzed the transcript levels of key genes in exocarps and seed integuments of berries from the same cultivar collected from HL and LL microclimates at three developmental stages, using real-time qPCR. In exocarp, the expression levels of genes involved in carbohydrate metabolism (VvSuSy1), phenylpropanoid (VvPAL1), stilbenoid (VvSTS1), and flavan-3-ol synthesis (VvDFR, VvLAR2, and VvANR) were highest at the green stage. In seeds, the expression of several genes associated with both phenylpropanoid (VvCHS1 and VvCHS3) and flavan-3-ol synthesis (VvDFR and VvLAR2) showed a peak at the véraison stage, whereas that of RuBisCO was maintained up to the mature stage. Overall, the HL microclimate, compared to that of LL, resulted in a higher expression of genes encoding elements associated with both photosynthesis (VvChlSyn and VvRuBisCO), carbohydrate metabolism (VvSPS1), and photoprotection (carotenoid pathways genes) in both tissues. HL also induced the expression of the VvFLS1 gene, which was translated into a higher activity of the FLS enzyme producing flavonol-type flavonoids, whereas the expression of several other flavonoid pathway genes (e.g., VvCHS3, VvSTS1, VvDFR, and VvLDOX) was reduced, suggesting a specific role of flavonols in photoprotection of berries growing in the HL microclimate. This work suggests a possible link at the transcriptional level between berry photosynthesis and pathways of primary and secondary metabolism, and provides relevant information for improving the management of the light microenvironment at canopy level of the grapes.

The effects of climate change are becoming a real concern for the viticulture sector, with impacts on both grapevine physiology and the quality of the fresh berries and wine. Short-term mitigation strategies, like foliar kaolin application and smart irrigation regimes, have been implemented to overcome these problems. We previously showed that these strategies also influence the photosynthetic activity of the berries themselves, specifically in the exocarp and seed. In the present work, we assessed the modulating effects of both canopy-light microclimate, kaolin and irrigation treatments on the metabolic profiles of the exocarp and seed, as well as the potential role of berry photosynthesis herein. Berries from the white variety Alvarinho were collected at two contrasting light microclimate positions within the vine canopy (HL—high light and LL—low light) from both irrigated and kaolin-treated plants, and their respective controls, at three fruit developmental stages (green, véraison and mature). Untargeted liquid chromatography mass spectrometry (LCMS) profiling of semi-polar extracts followed by multivariate statistical analysis indicate that both the light microclimate and irrigation influenced the level of a series of phenolic compounds, depending on the ripening stage of the berries. Moreover, untargeted gas chromatography mass spectrometry (GCMS) profiling of polar extracts show that amino acid and sugar levels were influenced mainly by the interaction of irrigation and kaolin treatments. The results reveal that both photosynthetically active berry tissues had a distinct metabolic profile in response to the local light microclimate, which suggests a specific role of photosynthesis in these tissues. A higher light intensity within the canopy mainly increased the supply of carbon precursors to the phenylpropanoid/flavonoid pathway, resulting in increased levels of phenolic compounds in the exocarp, while in seeds, light mostly influenced compounds related to carbon storage and seed development. In addition, our work provides new insights into the influence of abiotic stress mitigation strategies on the composition of exocarps and seeds, which are both important tissues for the quality of grape-derived products.

Crooked architectures of Quercus pubescens were found on the mega lapies of the Païolive woodland, in south-central France. Seventy-two individuals were selected to establish a morphological typology. Twelve oaks (10 crooked trees, and 2 referent trees) among the 72 individuals were cored to the heart of the tree. Hemispherical photographs characterized light conditions beneath the canopy. Categories 1 to 5 (i.e., 90% of individuals) had a single stem. The estimated age of the trees varied from 45 to 130 years. Crooked oaks reacted similarly to erect oaks with regard to interannual variations in the local climate. Mean LAI (leaf index area) (3.9) displayed strong variations from one site to another (range 2.2-6.2). Crookedness can be explained by several hypothesis: 1) the short flexures of the main stems may limit cavitation in situations where fissures are lacking or 2) already colonized by the roots of neighboring trees; 3) young oaks were seeking the sun and may have grown creeping until they reached a tree-fall or a felling area. [ABSTRACT FROM AUTHOR]

The contribution of light and thermal conditions to berry anthocyanin accumulation was investigated in grapevine Vitis vinifera L. cv. Cannonau/1103P subjected to different irrigation strategies in Sardinia, Italy in 2009. In two of the deficit irrigation treatments the root system received 50% and 25% crop evapotranspiration (ETc), referred to as DI50 and DI25, respectively. In the third treatment, which included partial root-zone drying (PRD), ETc was set at 50%. All three treatments were compared to a full irrigation control (FI), thus 100% ETc. Analysis of the thermal conditions during the growing season in 2009 provided evidence for a high frequency of elevated temperatures (> 30°C) during berry development. During ripening, the DI25 clusters intercepted significantly higher intensities (P < 0.01) of solar radiation, UV and PAR, particularly on the southeast canopy side, in comparison to FI and PRD. The analysis of berry temperatures in the DI treatments showed higher exposure to more than 35°C in the DI25 southeast berries. Thermal time for anthocyanin accumulation was computed for the DI50 and DI25 berries using normal heat hours (NHH). The patterns of daily NHH showed a reduction in thermal efficiency for anthocyanin accumulation during mid-ripening in the DI25 southeast berries compared to the DI50 ones. The higher temperatures at mid-ripening led to lower total anthocyanin contents in the DI25 berries. However, the coumaroyl-glucoside anthocyanin forms continued to increase in both the DI50 and DI25 berries, while a significant reduction in berry total contents of these forms was observed in FI and PRD. Both deficit irrigation and light conditions in the DI25 berries favoured the accumulation of more colour-stable anthocyanins in the berry skin until harvest, namely p-coumaroyl-glucoside and acetyl-glucoside forms. [ABSTRACT FROM AUTHOR]

Abstract: Light absorption by plant organs affects the development of a canopy directly through photobiological processes as well as indirectly through its action on organ temperature. Recent radiative models enable light absorption to be estimated for each individual organ within a canopy. These models require parameters describing incident radiation, canopy structure, and optical properties of phytoelements. Among these parameters, the bidirectional optical properties of phytoelements are a stumbling block: they are difficult to measure and take into account efficiently. Thus, most radiative models resort to what is referred to the Lambertian approximation. However, few studies have verified its suitability. In this paper, we assess this approximation in terms of individual leaf absorption for dense crop canopies in the solar spectrum. Simulations were performed with Monte Carlo ray tracing for three canopies, three sun positions, and two spectral domains (photosynthetically active radiation (PAR) and near infrared (NIR)). Results validate the suitability of the Lambertian approximation to simulate the light absorption by plants given the conditions under study. [Copyright &y& Elsevier]

The aim of this study was to determine the effects of date of summer pruning and cane densities on growth and fruiting characteristics of the raspberry (Rubus idaeus) plant. Three summer-pruning dates (early, middle, and late July) and four cane densities (8, 16, 24, and 32 canes/m row) were imposed to the greenhouse-grown primocane-fruiting raspberry 'Autumn Bliss' in 2 consecutive years (1994 and 1995). A higher light microclimate and CO2 assimilation rate were measured within the canopy at the lowest density. Some compensation in CO2 assimilation rates were observed in the upper leaves of the high-density treatments, probably in response to low light. Delayed pruning decreased yield per cane and per row. The highest yields per cane were always observed at the lowest cane density. Densities of 16 and 24 canes/m produced the highest fruit yield. Light conditions appeared to be the most important environmental factor affecting plant productivity. Fruit were a weaker sink than roots; therefore, the role of carbohydrate reserves should be investigated. [ABSTRACT FROM AUTHOR]

ABSTRACT Shoot architecture has been investigated using the ratio of mean shoot silhouette area to total needle area ( &figmu1-1;) as a structural index of needle clumping in shoot space, and as the effective extinction coefficient of needle area. Although &figmu1-2; can be used effectively for the prediction of canopy gap fraction, it does not provide information about the within-shoot radiative regime. For this purpose, the estimation of three architectural properties of the shoots is required: needle area density, angular distribution and spatial aggregation. To estimate these features, we developed a method based on the inversion of a Markov three-dimensional interception model. This approach is based on the turbid medium approximation for needle area in the shoot volume, and assumes an ellipsoidal angular distribution of the normals to the needle area. Observed shoot dimensions and silhouette areas for different vertical and azimuth angles (A S ) are used as model inputs. The shape coefficient of the ellipsoidal distribution (c ) and the Markov clumping index (λ 0 ) are estimated by a least square procedure, in order to minimize the differences between model prediction and measurements of A S . This methodology was applied to silver fir (Abies alba Mill.) shoots collected in a mixed fir–beech–spruce forest in the Italian Alps. The model worked effectively over the entire range of shoot morphologies: c ranged from 1 to 8 and λ 0 from 0·3 to 1 moving from the top to the base of the canopy. Finally, the shoot model was applied to reconstruct the within-shoot light regime, and the potential of this technique in upscaling photosynthesis to the canopy level is discussed. [ABSTRACT FROM AUTHOR]

Viticulture practices that change the light distribution in the grapevine canopy can interfere with several physiological mechanisms, such as grape berry photosynthesis and other metabolic pathways, and consequently impact the berry biochemical composition, which is key to the final wine quality. We previously showed that the photosynthetic activity of exocarp and seed tissues from a white cultivar (Alvarinho) was in fact responsive to the light microclimate in the canopy (low and high light, LL and HL, respectively), and that these different light microclimates also led to distinct metabolite profiles, suggesting a berry tissue-specific interlink between photosynthesis and metabolism. In the present work, we analyzed the transcript levels of key genes in exocarps and seed integuments of berries from the same cultivar collected from HL and LL microclimates at three developmental stages, using real-time qPCR. In exocarp, the expression levels of genes involved in carbohydrate metabolism (VvSuSy1), phenylpropanoid (VvPAL1), stilbenoid (VvSTS1), and flavan-3-ol synthesis (VvDFR, VvLAR2, and VvANR) were highest at the green stage. In seeds, the expression of several genes associated with both phenylpropanoid (VvCHS1 and VvCHS3) and flavan-3-ol synthesis (VvDFR and VvLAR2) showed a peak at the véraison stage, whereas that of RuBisCO was maintained up to the mature stage. Overall, the HL microclimate, compared to that of LL, resulted in a higher expression of genes encoding elements associated with both photosynthesis (VvChlSyn and VvRuBisCO), carbohydrate metabolism (VvSPS1), and photoprotection (carotenoid pathways genes) in both tissues. HL also induced the expression of the VvFLS1 gene, which was translated into a higher activity of the FLS enzyme producing flavonol-type flavonoids, whereas the expression of several other flavonoid pathway genes (e.g., VvCHS3, VvSTS1, VvDFR, and VvLDOX) was reduced, suggesting a specific role of flavonols in photoprotection of berries growing in the HL microclimate. This work suggests a possible link at the transcriptional level between berry photosynthesis and pathways of primary and secondary metabolism, and provides relevant information for improving the management of the light microenvironment at canopy level of the grapes. [ABSTRACT FROM AUTHOR]

Changes in canopy structure parameters (leaflet orientation, leaflet inclination and leaf area index) were measured in crops of beans ( Phaseolus vulgaris L.) in the field as the canopy developed between July and October. These changes were compared with the corresponding changes in seasonal light transmission. The beans showed clear heliotropic behaviour, with preferential orientation of leaflets towards the sun’s beam, especially on sunny days. Nevertheless a significant proportion of the leaves pointed in other directions, with as much as 20% oriented towards the north. The highest proportion of leaf inclinations was in the range 30–40° on cloudy days and between 40° and 50° on sunny days. Two methods were compared for assessing changes in light transmission: (a) the use of a Sunfleck Ceptometer and (b) the use of continuous records obtained with sensors installed in the canopy. Over the growth period studied, the total of the leaf plus stem area indices ( LS) increased from 0.26 to 5.2 with the transmission coefficient (τ) for photosynthetic photon flux density (PPFD), obtained using the Ceptometer, correspondingly decreasing from 0.72 to 0.05, and the canopy extinction coefficient decreasing from 1.4 to 0.62. The continuous records of light transmission gave generally similar estimates of τ. Some contrasting leaf angle distribution functions were compared for estimation of LS from the light measurements. The best leaf angle function to predict LS from the observed light transmission was a conical function corrected by the degree of heliotropism. [ABSTRACT FROM AUTHOR]

Photosynthetic photon flux density (PPFD) fluctuations were quantified in crops of beans ( Phaseolus vulgaris L.) in the field as the canopy developed between July and October. Two different methods were used to select sunflecks and shadeflecks. Four ranges of zenith angles (60–70°, 50–60°, 40–50° and 30–40°) were selected for analysing PPFD fluctuations. At the base of the canopy, sunflecks contributed 18%, 53%, 10% and 4% during the 1st, 3rd, 5th and 7th week of growth, respectively. At a height of 20 cm above the soil surface, the respective contributions were 28% and 21% during the 6th and 7th weeks. Sunfleck lengths of 0–5 s were the most frequent, with the greatest number being found with smaller zenith angles. The proportion of short duration sunflecks increased as the growth period advanced. The number of long sunflecks decreased with time, with very few longer than 100 s by the 5th and 7th weeks. The distributions of sunfleck irradiance were similar to normal distributions and irradiance ranged in μmol m−2 s−1 from 600–900, 800–1500 and 1000–1600 respectively at zenith angles of 50–60°, 40–50° and 30–40°. A multiple regression showed that short sunflecks (<100 s) depended on zenith angle, plant height, and leaf and stem area index ( L s), whereas long sunflecks (>100 s) depended on zenith angle and Ls. Shadefleck distributions were similar to those for sunflecks but there were fewer of the shortest examples and more of the longest. The best statistical distribution to describe sunflecks and shadeflecks was the gamma distribution, which could provide the basis for the future development of a good model for sunfleck and shadefleck distributions. [ABSTRACT FROM AUTHOR]

The effects of climate change are becoming a real concern for the viticulture sector, with impacts on both grapevine physiology and the quality of the fresh berries and wine. Short-term mitigation strategies, like foliar kaolin application and smart irrigation regimes, have been implemented to overcome these problems. We previously showed that these strategies also influence the photosynthetic activity of the berries themselves, specifically in the exocarp and seed. In the present work, we assessed the modulating effects of both canopy-light microclimate, kaolin and irrigation treatments on the metabolic profiles of the exocarp and seed, as well as the potential role of berry photosynthesis herein. Berries from the white variety Alvarinho were collected at two contrasting light microclimate positions within the vine canopy (HL—high light and LL—low light) from both irrigated and kaolin-treated plants, and their respective controls, at three fruit developmental stages (green, véraison and mature). Untargeted liquid chromatography mass spectrometry (LCMS) profiling of semi-polar extracts followed by multivariate statistical analysis indicate that both the light microclimate and irrigation influenced the level of a series of phenolic compounds, depending on the ripening stage of the berries. Moreover, untargeted gas chromatography mass spectrometry (GCMS) profiling of polar extracts show that amino acid and sugar levels were influenced mainly by the interaction of irrigation and kaolin treatments. The results reveal that both photosynthetically active berry tissues had a distinct metabolic profile in response to the local light microclimate, which suggests a specific role of photosynthesis in these tissues. A higher light intensity within the canopy mainly increased the supply of carbon precursors to the phenylpropanoid/flavonoid pathway, resulting in increased levels of phenolic compounds in the exocarp, while in seeds, light mostly influenced compounds related to carbon storage and seed development. In addition, our work provides new insights into the influence of abiotic stress mitigation strategies on the composition of exocarps and seeds, which are both important tissues for the quality of grape-derived products. [ABSTRACT FROM AUTHOR]

Photosynthetic carbon assimilation rates are highly dependent on environmental factors such as light availability and on metabolic limitations such as the demand for carbon by sink organs. The relative effects of light and sink demand on photosynthesis in perennial plants such as trees remain poorly characterized. The aim of the present study was therefore to characterize the relationships between light and fruit load on a range of leaf traits including photosynthesis, non-structural carbohydrate content, leaf structure, and nitrogen-related variables in fruiting ('ON') and non-fruiting ('OFF') 'Golden Delicious' apple trees. We show that crop status (at the tree scale) exerts a greater influence over leaf traits than the local light environment or the local fruit load. High rates of photosynthesis were observed in the ON trees. This was correlated with a high leaf nitrogen content. In contrast, little spatial variability in photosynthesis rates was observed in the OFF trees. The lack of variation in photosynthesis rates was associated with high leaf non-structural carbohydrate content at the tree level. Taken together, these results suggest that low carbon demand leads to feedback limitation on photosynthesis resulting in a low level of within-tree variability. These findings provide new insights into carbon and nitrogen allocations within trees, which are heavily dependent on carbon demand., (© The Author(s) 2020. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)