Monochromatic light increases anthocyanin content during fruit development in bilberry.

Laura Zoratti,Laura Jaakola,Katja Karppinen,Stefan Martens,Marian Sarala,Lara Giongo,Hely Häggman,Elisabete Carvalho

doi:10.1186/s12870-014-0377-1

Abstract

BackgroundLight is one of the most significant environmental factors affecting to the accumulation of flavonoids in fruits. The composition of the light spectrum has been shown to affect the production of phenolic compounds during fruit ripening. However, specific information on the biosynthesis of flavonoids in fruits in response to different wavelengths of light is still scarce. In the present study bilberry (Vaccinium myrtillus L.) fruits, which are known to be rich with anthocyanin compounds, were illuminated with blue, red, far-red or white light during the berry ripening process. Following the illumination, the composition of anthocyanins and other phenolic compounds was analysed at the mature ripening stage of fruits.ResultsAll the three monochromatic light treatments had significant positive effect on the accumulation of total anthocyanins in ripe fruits compared to treatment with white light or plants kept in darkness. The elevated levels of anthocyanins were mainly due to a significant increase in the accumulation of delphinidin glycosides. A total of 33 anthocyanin compounds were detected in ripe bilberry fruits, of which six are novel in bilberry (cyanidin acetyl-3-O-galactose, malvidin acetyl-3-O-galactose, malvidin coumaroyl-3-O-galactose, malvidin coumaroyl-3-O-glucose, delphinidin coumaroyl-3-O-galactose, delphinidin coumaroyl-3-O-glucose).ConclusionsOur results indicate that the spectral composition of light during berry development has significant effect on the flavonoid composition of ripe bilberry fruits.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-014-0377-1) contains supplementary material, which is available to authorized users.

Highlights

Light is one of the most significant environmental factors affecting to the accumulation of flavonoids in fruits
Anthocyanins are biosynthesized via the phenylpropanoid/flavonoid pathway consisting of a number of enzymatic steps that catalyze a sequential reaction leading to the production of different anthocyanidins including delphinidins (Dp), cyanidins (Cy), petunidins (Pt), peonidins (Pn) and malvidins (Mv) (Additional file 1)
The phenolic compounds other than anthocyanins present in ripe bilberry fruits were analyzed by a UPLC-MS/MS

Summary

Introduction

Light is one of the most significant environmental factors affecting to the accumulation of flavonoids in fruits. Anthocyanins, a class of flavonoid compounds, are the main pigments found in many flowers and fruits, in which they act as insect and animal attractants and protect the plant from light oxidative stress [1]. These metabolites are powerful antioxidants and shown to be beneficial for human health [2]. Bilberry fruits are known to accumulate high yields of various anthocyanins both in skin and flesh during the ripening period, genetic and environmental factors are reported to affect the final composition [8,9,10]. The phenylpropanoid pathway responds to various environmental stimuli such as temperature, photoperiod, soil fertility [10,13,14] and light in particular [15,16]

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