Gamma rays as a type of ionizing radiation constitute a physical mutagen that induces mutations and could be effectively used in plant breeding. To compare the effects of gamma and ionizing irradiation according to exposure time in common wheat (Keumgang, IT 213100), seeds were exposed to ⁶⁰Co gamma rays at different dose rates. To evaluate the amount of free radical content, we used electron spin resonance spectroscopy. Significantly more free radicals were generated in the case of long-term compared with short-term gamma-ray exposure at the same dose of radiation. Under short-term exposure, shoot and root lengths were slightly reduced compared with those of the controls, whereas long-term exposure caused severe growth inhibition. The expression of antioxidant-related and DNA-repair-related genes was significantly decreased under long-term gamma-ray exposure. Long-term exposure caused higher radiosensitivity than short-term exposure. The results of this study could help plant breeders select an effective mutagenic induction dose rate in wheat.

Chrysanthemum morifolium Ramat is a perennial flowering plant widely cultivated for use in a tea infusion and as a popular beverage. To identify and evaluate the tea infusion made with a γ-irradiated mutant chrysanthemum cultivar with dark purple petals (cv. ARTI-Dark Chocolate), its phytochemical composition and antioxidant activity were tested and compared with those of the commercially available chrysanthemum cultivar with yellow petals (cv. Gamguk) by HPLC-DAD-ESIMS, as well as DPPH and ABTS radical scavenging assays. The purple chrysanthemum tea contained anthocyanins and linarin, which were not detected in the yellow chrysanthemum tea and the content of chlorogenic acid, acacetin-7-O-β-glucoside, and luteolin was higher compared with the yellow chrysanthemum tea. In contrast, the yellow chrysanthemum tea had higher luteolin-7-O-β-glucoside, 3,5-dicaffeoylquinic acid, apigenin-7-O-β-glucoside, and apigenin contents in comparison with the purple chrysanthemum tea. In addition, the content and antioxidant activity of the two chrysanthemum teas were investigated according to different water temperatures and infusing time. The yellow chrysanthemum tea did not show any significant differences according to infusing time and temperature, while the purple chrysanthemum tea was more influenced by the infusing time than water temperature, showing the highest total compound content in the infusing condition of 100 °C and 4 min. Moreover, the floral scent volatiles of the two chrysanthemum tea sources were analyzed using HS-SPME-GC-MS. In the DPPH radical scavenging assay, the purple chrysanthemum tea broadly showed greater antioxidant activity than did the yellow chrysanthemum tea, corresponding to the high content of anthocyanins known as the powerful antioxidant. Further, both chrysanthemum flower teas exhibited strong ABTS radical scavenging effects ranging from 76% to 61% under all infusing conditions. Therefore, the purple chrysanthemum cultivar, ARTI-Dark Chocolate, is worthy of breeding as a new tea cultivar.

The response to gamma irradiation varies among plant species and is affected by the total irradiation dose and dose rate. In this study, we examined the immediate and ensuing responses to acute and chronic gamma irradiation in rice (Oryza sativa L.). Rice plants at the tillering stage were exposed to gamma rays for 8 h (acute irradiation) or 10 days (chronic irradiation), with a total irradiation dose of 100, 200, or 300 Gy. Plants exposed to gamma irradiation were then analyzed for DNA damage, oxidative stress indicators including free radical content and lipid peroxidation, radical scavenging, and antioxidant activity. The results showed that all stress indices increased immediately after exposure to both acute and chronic irradiation in a dose-dependent manner, and acute irradiation had a greater effect on plants than chronic irradiation. The photosynthetic efficiency and growth of plants measured at 10, 20, and 30 days post-irradiation decreased in irradiated plants, i.e., these two parameters were more severely affected by acute irradiation than by chronic irradiation. In contrast, acutely irradiated plants produced seeds with dramatically decreased fertility rate, and chronically irradiated plants failed to produce fertile seeds, i.e., reproduction was more severely affected by chronic irradiation than by acute irradiation. Overall, our findings suggest that acute gamma irradiation causes instantaneous and greater damage to plant physiology, whereas chronic gamma irradiation causes long-term damage, leading to reproductive failure.

The flowers of chrysanthemum species are used as a herbal tea and in traditional medicine. In addition, members of the genus have been selected to develop horticultural cultivars of diverse floral colors and capitulum forms. In this research, we investigated the phytochemical composition of eight gamma-irradiation mutant cultivars of Chrysanthemum morifolium and their original cultivars. The mutant chrysanthemum cultivars were generated by treatment with various doses of ⁶⁰Co gamma irradiation of stem cuttings of three commercial chrysanthemum cultivars as follows: ‘ARTI-Dark Chocolate’ (50Gy), ‘ARTI-Purple Lady’ (30 Gy), and ‘ARTI-Yellow Star’ (50 Gy) derived from ‘Noble Wine’; ‘ARTI-Red Star’ (50 Gy) and ‘ARTI-Rising Sun’ (30 Gy) from ‘Pinky’; ‘ARTI-Purple’ (40 Gy) and ‘ARTI-Queen’ (30 Gy) from ‘Argus’; and ‘ARTI-Rollypop’ (70 Gy) from ‘Plaisir d’amour’. Quantitative analysis of flavonoids, phenolic acids, anthocyanins, and carotenoids in the flowers of the 12 chrysanthemum cultivars was performed using high performance liquid chromatography-diode array detector-electrospray ionization mass spectrometry (HPLC-DAD-ESIMS). Essential oils from the flowers of these cultivars were analyzed by gas chromatography–mass spectrometry (GC-MS). The mutant cultivars, ‘ARTI-Dark Chocolate’, ‘ARTI-Purple Lady’, ‘ARTI-Purple’, and ‘ARTI-Queen’ showed higher total amounts of flavonoid and phenolic acid compared with those of the respective original cultivars. The mutant cultivars, ‘ARTI-Dark Chocolate’, ‘ARTI-Purple Lady’ and ‘ARTI-Purple’, which produce purple to pink petals, contained more than two-times higher amounts of anthocyanins compared with those of their original cultivars. Of the mutant cultivars, ‘ARTI-Yellow Star’ in which petal color was changed to yellow, showed the greatest accumulation of carotenoids. Ninety-nine volatile compounds were detected, of which hydrocarbons and terpenoids were abundant in all cultivars analyzed. This is the first report that demonstrated the phytochemical analysis of novel chrysanthemum cultivars derived from C. morifolium hydrid using HPLC-DAD-ESIMS and GC-MS. These findings suggest that the selected mutant chrysanthemum cultivars show potential as a functional source of phytochemicals associated with the abundance of health-beneficial components, as well as good source for horticulture and pigment industries.

Hibiscus species are rich in phenolic compounds and have been traditionally used for improving human health through their bioactive activities. The present study investigated the phenolic compounds of leaf extracts from 18 different H. acetosella accessions and evaluated their biofunctional properties, focusing on antioxidant and antibacterial activity. The most abundant phenolic compound in H. acetosella was caffeic acid, with levels ranging from 14.95 to 42.93 mg/100 g. The antioxidant activity measured by the ABTS assay allowed the accessions to be classified into two groups: a high activity group with red leaf varieties (74.71–84.02%) and a relatively low activity group with green leaf varieties (57.47–65.94%). The antioxidant activity was significantly correlated with TAC (0.933), Dp3-Sam (0.932), Dp3-Glu (0.924), and Cy3-Sam (0.913) contents (p < 0.001). The H. acetosella phenolic extracts exhibited antibacterial activity against two bacteria, with zones of inhibition between 12.00 and 13.67 mm (Staphylococcus aureus), and 10.67 and 13.33 mm (Pseudomonas aeruginosa). All accessions exhibited a basal antibacterial activity level (12 mm) against the Gram-positive S. aureus, with PI500758 and PI500764 exhibiting increased antibacterial activity (13.67 mm), but they exhibited a more dynamic antibacterial activity level against the Gram-negative P. aeruginosa.