Hydrogen peroxide, nitric oxide and UV RESISTANCE LOCUS8 interact to mediate UV-B-induced anthocyanin biosynthesis in radish sprouts

Abstract

The cross talk among hydrogen peroxide (H2O2), nitric oxide (NO) and UV RESISTANCE LOCUS8 (UVR8) in UV-B-induced anthocyanin accumulation in the hypocotyls of radish sprouts was investigated. The results showed that UV-B irradiation significantly increased the anthocyanin accumulation and the expression of UVR8, and a similar trend appeared in radish sprouts subjected to cadmium, chilling and salt stresses regardless of light source. However, these responses disappeared under dark exposure. These results suggest that abiotic stress-induced anthocyanin accumulation and UVR8 expression were light-dependent. Moreover, abiotic stresses all enhanced the production of H2O2 and exogenous H2O2 addition significantly increased the anthocyanin concentration and UVR8 transcription, while these increases were severely inhibited by addition of dimethylthiourea (DMTU, a chemical trap for H2O2). It seems to suggest that H2O2 played an important role in the anthocyanin biosynthesis. Furthermore, addition of 0.5 mM sodium nitroprusside (SNP, a NO-releasing compound) substantially induced the anthocyanin accumulation, and H2O2-induced anthocyanin accumulation and UVR8 expression were significantly suppressed by co-treatment with 2-phenyl-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl (PTIO, a NO scavenger), which was parallel with the expression of anthocyanin biosynthesis-related transcription factors and structural genes. All these results demonstrate that both H2O2 and NO are involved in UV-B-induced anthocyanin accumulation, and there is a crosstalk between them as well as a classical UVR8 pathway.

Functional analysis of the UVR8 photoreceptor from the monocot Zea mays

“…That is similar to Betula platyphylla UVR8 (BpUVR8) expression, which is induced by UV-B, and decreased after 9h of continuous irradiation [38]. On the other hand, UVR8 expression is increased by UV-B in the hypocotyls of radish sprouts [39]. Variations in UVR8 expression were also reported in UV-B treated fruit skin and apple callus [40].…”

Combined transcriptomic and proteomic analysis constructs a new model for light‐induced anthocyanin biosynthesis in eggplant (Solanum melongena L.)

“…As we all know, some photoreceptors participated in light‐induced anthocyanin biosynthesis through interact with COP1, including CRY1/2 and UVR8 (Jiang et al, ; Wu et al, ). In this study, we found that CRY3 and UVR3 were up‐0‐regulated by light and the expression pattern of CRY3 was similar with CRY1 and CRY2 reported in Jiang et al () and consistent with the anthocyanin accumulation.…”

Photomorphogenic responses to ultraviolet‐B light

“…UVR8 expression is subject to developmental regulation and inhibition by shading and elevated temperature in Vitis vinifera (grape) berries (Liu et al ; Loyola et al , who refer to VvUVR8 as UVR1) and is stimulated by UV‐B in apple fruits (Zhao et al ) and sunlight in litchi fruits (Zhang et al ). In radish ( Raphanus sativus ), UV‐B exposure and abiotic stresses stimulate UVR8 expression, and evidence was presented that these responses involve hydrogen peroxide and NO signaling (Wu et al ). Furthermore, examination of genomic data reveals that some plant species have several UVR8 genes, raising the possibility of differential expression.…”