Unveiling the shade nature of cyanic leaves: A view from the “blue absorbing side” of anthocyanins

Abstract

Anthocyanins have long been suggested as having great potential in offering photoprotection to plants facing high light irradiance. Nonetheless, their effective ability in protecting the photosynthetic apparatus from supernumerary photons has been questioned by some authors, based upon the inexact belief that anthocyanins almost exclusively absorb green photons, which are poorly absorbed by chlorophylls. Here we focus on the blue light absorbing features of anthocyanins, a neglected issue in anthocyanin research. Anthocyanins effectively absorb blue photons: the absorbance of blue relative to green photons increases from tri-to mono-hydroxy Bring substituted structures, reaching up to 50% of green photons absorption. We offer a comprehensive picture of the molecular events activated by low blue-light availability, extending our previous analysis in purple and green basil, which we suggest to be responsible for the "shade syndrome" displayed by cyanic leaves. While purple leaves display overexpression of genes promoting chlorophyll biosynthesis and light harvesting, in green leaves it is the genes involved in the stability/repair of photosystems that are largely overexpressed. As a corollary, this adds further support to the view of an effective photoprotective role of anthocyanins. We discuss the profound morpho-anatomical adjustments imposed by the epidermal anthocyanin shield, which reflect adjustments in light harvesting capacity under imposed shade and make complex the analysis of the photosynthetic performance of cyanic versus acyanic leaves.

A Review of Strawberry Photobiology and Fruit Flavonoids in Controlled Environments

“…The most prevalent secondary metabolites in strawberry fruits are flavonoids, including anthocyanins (Aaby et al, 2012), which are associated with antioxidative and anti-inflammatory properties. Flavonoids predominantly protect plants from UV radiation (Panche et al, 2016), and anthocyanins protect plants from blue and green light (Landi et al, 2020a). In recent years, known antioxidant properties of strawberry fruit have prompted the rise of its global consumption.…”

Plant–plant interactions

“…Beyond the review articles, the papers in this Special Issue can be divided into three themes, the first being light signalling. Although light signalling represents perhaps the most well‐known and intensively studied aspect of plant–plant interactions, two opinion articles, examining the effect of light reflected from below the canopy (Zhang, Evers, Anten, & Marcelis, 2020), and the self‐shading effect of anthocyanin production (Landi et al, 2020), illustrate how much there is still to find out. Two further original articles develop the light signalling theme further, in the context of crop–weed and plant–parasite interactions.…”

Filtering Light-Emitting Diodes to Investigate Amber and Red Spectral Effects on Lettuce Growth

“…Red and purple coloration in fruit and leaves is typically due to anthocyanin, a polyphenolic pigment [51]. Anthocyanin biosynthesis is often associated with high light conditions [52], as well as ultraviolet radiation and blue light [53,54]. In lettuce plants, anthocyanin accumulation can be induced by supplementing 373-, 455-, 460-, 476-, 505-, 658-, and 660-nm light with different light sources such as HPS lamps, solar light, and white fluorescent lamps [55][56][57].…”