UV-B radiation affects flavonoids and fungal colonisation in Fagopyrum esculentum and F. tataricum

Abstract

In the present study, we have evaluated the effects of increased UV-B radiation that simulates 17% ozone depletion, on fungal colonisation and concentrations of rutin, catechin and quercetin in common buckwheat (Fagopyrum esculentum) and tartary buckwheat (Fagopyrum tataricum). Induced root growth and reduced shoot:root ratios were seen in both of these buckwheat species after enhanced UV-B radiation. There was specific induction of shoot quercetin concentrations in UV-B-treated common buckwheat, whereas there were no specific responses for flavonoid metabolism in tartary buckwheat. Root colonisation with arbuscular mycorrhizal fungi significantly reduced catechin concentrations in common buckwheat roots, and induced rutin concentrations in tartary buckwheat, but did not affect shoot concentrations of the measured phenolics. Specific UV-B-related reductions in the density of microsclerotia were observed in tartary buckwheat, indicating a mechanism that potentially affects fungus-plant interactions. The data support the hypothesis that responses to enhanced UV-B radiation can be influenced by the plant pre-adaptation properties and related changes in flavonoid metabolism.

UV-B radiation increases anthocyanin levels in cotyledons and inhibits the growth of common buckwheat seedlings

“…In Primula veris leaves, UV had no effect on total flavonoid levels, but it exerted a varied effect on flavonoids [9]. Our results also partially confirm the findings of Regvar et al [24]. In the cited study, supplementary UV-B did not affect the rutin levels in common buckwheat plants, but it should be noted that the experiment was conducted outdoors over a long period of time.…”

“…Plants could respond to excessive irradiation by biosynthesizing phenylpropanoids whose presence in the upper epidermis creates a solar screen that absorbs UV before it can reach sensitive targets such as chloroplasts [23,27]. However, individual phenylpropanoids in plants were found to respond differently to UV-B [8,9,22,24]. For instance, in the leaves of Hydrocotyle leucocephala, quercetin derivatives accumulated under exposure to UV-B, thus reducing the concentrations of kaempferol glycosides and chlorogenic acid [20].…”

“…Buckwheat seedlings also contain glycosides of cyanidin which occur mainly in the reddish hypocotyl and, in smaller amounts, in the cotyledons [14,29]. Due to their high flavonoid content, buckwheat plant is often used in research examining the effects of UV radiation on these compounds [7,11,16,24,25,28,31].…”

Nitric Oxide as a Signal in Inducing Secondary Metabolites During Plant Stress

“…Among various physical variables, ultraviolet (UV) irradiation was considered to be the major inducer of secondary metabolites in several plant species including peanut, rice, maize, and basil [51,52]. UV-B has been seen to increase flavonoids in barley, several Passiflora species [50].…”

Effect of ultraviolet-B radiation on arbuscular mycorrhizal colonization of two rangeland weeds

“…We hypothesized that stress, induced by increased UV-B radiation levels, may affect this symbiosis. Recent studies of Regvar et al (2012) proved that UV-B radiation decreases the number of microsclerotia of fungi colonizing buckwheat (Fagopyrum esculentum) and tatar buckwheat (Fagopyrum tataricum).…”