Field-Grown Grapevine Berries Use Carotenoids and the Associated Xanthophyll Cycles to Acclimate to UV Exposure Differentially in High and Low Light (Shade) Conditions

Abstract

Light quantity and quality modulate grapevine development and influence berry metabolic processes. Here we studied light as an information signal for developing and ripening grape berries. A Vitis vinifera Sauvignon Blanc field experiment was used to identify the impacts of UVB on core metabolic processes in the berries under both high light (HL) and low light (LL) microclimates. The primary objective was therefore to identify UVB-specific responses on berry processes and metabolites and distinguish them from those responses elicited by variations in light incidence. Canopy manipulation at the bunch zone via early leaf removal, combined with UVB-excluding acrylic sheets installed over the bunch zones resulted in four bunch microclimates: (1) HL (control); (2) LL (control); (3) HL with UVB attenuation and (4) LL with UVB attenuation. Metabolite profiles of three berry developmental stages showed predictable changes to known UV-responsive compound classes in a typical UV acclimation (versus UV damage) response. Interestingly, the berries employed carotenoids and the associated xanthophyll cycles to acclimate to UV exposure and the berry responses differed between HL and LL conditions, particularly in the developmental stages where berries are still photosynthetically active. The developmental stage of the berries was an important factor to consider in interpreting the data. The green berries responded to the different exposure and/or UVB attenuation signals with metabolites that indicate that the berries actively managed its metabolism in relation to the exposure levels, displaying metabolic plasticity in the photosynthesis-related metabolites. Core processes such as photosynthesis, photo-inhibition and acclimation were maintained by differentially modulating metabolites under the four treatments. Ripe berries also responded metabolically to the light quality and quantity, but mostly formed compounds (volatiles and polyphenols) that have direct antioxidant and/or “sunscreening” abilities. The data presented for the green berries and those for the ripe berries conform to what is known for UVB and/or light stress in young, active leaves and older, senescing tissues respectively and provide scope for further evaluation of the sink/source status of fruits in relation to photosignalling and/or stress management.

Influence of Foliar Kaolin Application and Irrigation on Photosynthetic Activity of Grape Berries

“…For the exocarps, dissipation or quenching mechanisms other than NPQ may explain the result, since this tissue maintains high photosynthetic activity until the mature stage (Figure 6a,c,e). Accumulation of carotenoids in white berries ('Sauvignon Blanc') was also increased in response to increasing levels of solar light in the canopy, which shows that the berries utilize these photosynthesis-related pigments in photo-acclimation responses and/or as "sunscreens" [58].…”

UV‐B irradiation differentially regulates terpene synthases and terpene content of peach

“…In addition, accumulation of carotenoids is also associated with plant acclimation to UV exposure (Joubert et al . ). Terpenoids comprise a large group of secondary metabolites, and the overall effects of UV on terpenoid emissions vary in different Mediterranean species (Llusia et al .…”

“…Some of the compounds produced, such as flavonoids, help protect plant cells from harmful effects of UV, and many are also important phytonutrients, which are beneficial to human health (Martin et al 2011;Ravaglia et al 2013;Loyola et al 2016;Matus 2016). In addition, accumulation of carotenoids is also associated with plant acclimation to UVexposure (Joubert et al 2016). Terpenoids comprise a large group of secondary metabolites, and the overall effects of UV on terpenoid emissions vary in different Mediterranean species (Llusia et al 2012).…”

Climate reconstruction for the Entre‐Douro‐e‐Minho region (NWPortugal) betweenAD1626 andAD1820: synthesis of viticulture data and foraminiferal evidence

“…Grapevines, like all plants, are particularly sensitive to photosynthetically active radiation (PAR; 400-700 nm), the energy source for the photosynthetic light-dependent reactions (Keller 2015). Furthermore, grapevines are able to recognize fluctuations in the incoming light intensity, its quality, periodicity and directionality (Keller 2015), which provides information about the surrounding environment (Joubert et al 2016). Different cultivars can exhibit different light sensitivities, but while they all perform well at both high temperature and light intensity, only a few exhibit the ability to give good yields under low temperatures and low light intensity conditions (e.g.…”

“…Generally, little growth occurs at temperatures below 10°C, and above 30-32°C growth slows down, stopping at 38°C (Monteiro et al 2005). Furthermore, grapevines are able to recognize fluctuations in the incoming light intensity, its quality, periodicity and directionality (Keller 2015), which provides information about the surrounding environment (Joubert et al 2016). Overcast skies during the bloom-set (flowering) or a PAR decrease induces a clear reduction in fruitfulness (e.g.…”