Articles
Blue light irradiation photorepairs DNA damage caused by UV-B irradiation in komatsuna (Brassica rapa var. perviridis)
Article number
1423_23
Pages
171 – 178
Language
English
Abstract
UV-B (wavelength 280-315 nm) irradiation is a method to increase the concentration of functional compounds in leafy vegetables.
However, excessive UV-B irradiation often causes DNA damage and growth inhibition.
In rice and Arabidopsis, DNA photolyase activity initiated by blue light alleviates growth inhibition caused by UV-B irradiation.
However, DNA photolyase activity has not been well-studied in leafy vegetables containing pigments and functional compounds as antioxidant.
In this study, komatsuna (Brassica rapa var. perviridis) at 15 days after sowing was exposed to treatments with UV-free red (R) and blue (B) light (photosynthetic photon flux density 200 µmol m‑2 s‑1) and UV-B combined R and B at 4.0 or 10 W m‑2 for 3 days (Experiment 1). Regardless of the UV-B radiant flux density, UV-B combined B-light alleviated the visible disorder and DNA damage compared to R-light and also increased the concentrations of ascorbic acid (AsA) and total polyphenol (TP). Either or both photolyase activation and polyphenols accumulation could be the reason for these alleviations.
In Experiment 2, komatsuna was exposed to 43 h of UV-B irradiation followed by 5 h of B or R-light or dark conditions.
Regardless of the light conditions, dark repair of DNA damage occurred.
DNA damage was significantly lower in the B-light treatment after UV-B irradiation than in the R-light and dark treatments.
There were no differences in growth, AsA, and TP concentrations among the treatments.
From these results, when AsA and TP concentrations were similar, komatsuna DNA photolyase activity was initiated by B-light irradiation after UV-B irradiation, and DNA damage by UV-B was reduced.
Furthermore, komatsuna DNA photolyase repaired damaged DNA in a shorter time than dark repair.
However, excessive UV-B irradiation often causes DNA damage and growth inhibition.
In rice and Arabidopsis, DNA photolyase activity initiated by blue light alleviates growth inhibition caused by UV-B irradiation.
However, DNA photolyase activity has not been well-studied in leafy vegetables containing pigments and functional compounds as antioxidant.
In this study, komatsuna (Brassica rapa var. perviridis) at 15 days after sowing was exposed to treatments with UV-free red (R) and blue (B) light (photosynthetic photon flux density 200 µmol m‑2 s‑1) and UV-B combined R and B at 4.0 or 10 W m‑2 for 3 days (Experiment 1). Regardless of the UV-B radiant flux density, UV-B combined B-light alleviated the visible disorder and DNA damage compared to R-light and also increased the concentrations of ascorbic acid (AsA) and total polyphenol (TP). Either or both photolyase activation and polyphenols accumulation could be the reason for these alleviations.
In Experiment 2, komatsuna was exposed to 43 h of UV-B irradiation followed by 5 h of B or R-light or dark conditions.
Regardless of the light conditions, dark repair of DNA damage occurred.
DNA damage was significantly lower in the B-light treatment after UV-B irradiation than in the R-light and dark treatments.
There were no differences in growth, AsA, and TP concentrations among the treatments.
From these results, when AsA and TP concentrations were similar, komatsuna DNA photolyase activity was initiated by B-light irradiation after UV-B irradiation, and DNA damage by UV-B was reduced.
Furthermore, komatsuna DNA photolyase repaired damaged DNA in a shorter time than dark repair.
Authors
S. Hikosaka, S. Asano, T. Kawarada, H. Yoshida, E. Goto
Keywords
antioxidant, dark repair, leafy vegetable, photolyase activity, ultra-violet
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