Differential Antioxidant Response to Supplemental UV-B Irradiation and Sunlight in Three Basil Varieties

Abstract

Three basil plant varieties (Ocimum basilicum var. Genovese, Ocimum × citriodorum, and Ocimum basilicum var. purpurascens) were grown under moderate light (about 300 µmol photons m−2 s−1) in a glasshouse or growth chamber and then either transferred to an open field (average daily dose: 29.2 kJ m−2 d−1) or additionally exposed to UV-B irradiation in a growth chamber (29.16 kJ m−2 d−1), to reveal the variety-specific and light-specific acclimation responses. Total antioxidant capacity (TAC), phenolic profile, ascorbate content, and class III peroxidase (POD) activity were used to determine the antioxidant status of leaves under all four light regimes. Exposure to high solar irradiation at the open field resulted in an increase in TAC, total hydroxycinnamic acids (HCAs, especially caffeic acid), flavonoids, and epidermal UV-absorbing substances in all three varieties, as well as a two-fold increase in the leaf dry/fresh weight ratio. The supplemental UV-B irradiation induced preferential accumulation of HCAs (rosmarinic acid) over flavonoids, increased TAC and POD activity, but decreased the ascorbate content in the leaves, and inhibited the accumulation of epidermal flavonoids in all basil varieties. Furthermore, characteristic leaf curling and UV-B-induced inhibition of plant growth were observed in all basil varieties, while a pro-oxidant effect of UV-B was indicated with H2O2 accumulation in the leaves and spotty leaf browning. The extent of these morphological changes, and oxidative damage depended on the basil cultivar, implies a genotype-specific tolerance mechanism to high doses of UV-B irradiation.

A Long-Term Study on Chemical Compounds and Their Location in Sweet Basil Leaves from Organic and Conventional Producers

“…Basil cultivated in an open-field cultivation system produced significantly more polyphenols compared to the greenhouse system. This is because more light was available for plants in an open-field system [52]. No significant interaction between the cultivation system and the experimental year was observed in the case of all phenolics (Table 1).…”

Urban Flora Riches: Unraveling Metabolic Variation Along Altitudinal Gradients in Two Spontaneous Plant Species

“…Because of their immobility, plants have developed strategies to protect themselves from the harmful action of UV-B radiation. Many studies point out the accumulation of secondary metabolites such as polyphenols, flavonoids, hydroxycinnamic acids, and tannins [ 9 , 10 , 11 ]. Around 90% of the incident UV-B radiation is attenuated before reaching the mesophyll [ 12 ].…”

The biochemical and growth-associated traits of basil (Ocimum basilicum L.) affected by silver nanoparticles and silver

“…The basil plant ( Ocimum basilicum L.), a member of the Lamiaceae family, includes the Purpurascens variety known for its high concentration of anthocyanins and phenols [ 29 , 30 ]. Despite the use of basil plant extracts as stabilizing agents for synthesizing zinc oxide nanoparticles [ 31 ], the impact of bulk silver and silver nanoparticles on this plant remains unexplored.…”