Increased phenylpropanoids production in UV-B irradiated Salvia verticillata as a consequence of altered genes expression in young leaves.

Ultraviolet-B (UV-B) radiation as an environmental potential elicitor induces the synthesis of plant secondary metabolites. The effects of UV-B radiation on photosynthetic pigments and dry weight, biochemical and molecular features of old and young leaves of Salvia verticillata were investigated. Plants were exposed to 10.97 kJ m-2 day-1 of biologically effective UV-B radiation for up to 10 days. The sampling process was performed in four steps: 1, 5, 10, and 13 days (recovery time) after the start of irradiation. As a result of plant investment in primary and secondary metabolism, the production of phenolic compounds increased, while chlorophyll levels and leaf dry weight (%) declined. Under long-term UV-B exposure, young leaves exhibited the most significant reduction in chlorophyll a and b content and leaf dry weight. The highest level of total phenol (1.34-fold) and flavonoid concentration (2-fold) relative to the control was observed on the 5th day and recovery time, respectively. Young leaves demonstrated the highest amount of phenolic acids in recovery time. Young leaves on the 5th day of the experiment exerted the highest level of antioxidant activity when compared to the control. A positive correlation was observed between antioxidant activity and the amount of phenolic compounds. Regarding the expression of phenylpropanoid pathway genes, UV-B enhanced the expression of phenylalanine ammonia-lyase, tyrosine aminotransferase, and rosmarinic acid synthase with the highest level in young leaves on the 10th day. Overall, young leaves of S. verticillata indicated higher sensitivity to UV-B radiation and developed more tangible reactions to such radiation.

Exogenous application of phytosulfokine α (PSKα) delays yellowing and preserves nutritional quality of broccoli florets during cold storage.

In this study, we tested the exogenous application of phytosulfokine α (PSKα) for delaying the yellowing of broccoli florets during cold storage. Our results showed that the lower yellowing in broccoli florets treated with 150 nM PSKα was probably due to the higher endogenous accumulation of PSKα, leading to the endogenous accumulation of guanosine 3', 5'-cyclic monophosphate (cGMP). Besides, broccoli florets treated with 150 nM PSKα exhibited a higher accumulation of phenols and flavonoids by triggering gene expression and activities of phenylalanine ammonia-lyase (PAL) and chalcone synthase (CHS). Moreover, the higher expression of L-galactotno-1,4-lactone dehydrogenase (GLDH) gene and the lower expression of ascorbic acid oxidase (AAO) gene in broccoli florets treated with 150 nM PSKα may be the reasons for the higher accumulation of ascorbic acid. In conclusion, the exogenous application of PSKα is a promising strategy in delaying the yellowing and preserving the nutritional quality of broccoli florets during cold storage.

Prestorage oxalic acid treatment maintained visual quality, bioactive compounds, and antioxidant potential of pomegranate after long-term storage at 2 degrees C.

Oxalic acid at three concentrations (2, 4, and 6 mM) was applied by dipping to pomegranate fruits of cv. Mollar de Elche, which were then stored for 84 days at 2 degrees C. Pomegranate is a chilling-sensitive fruit and, thus, control fruits exhibited chilling injury (CI) symptoms after long-term storage at 2 degrees C that were accompanied by increased respiration rate, weight loss, and electrolyte leakage (EL). The CI symptoms were significantly reduced by oxalic acid treatment, especially for the 6 mM concentration. In addition, control pomegranates showed significant reduction in the content of total phenolics and ascorbic acid as well as in total antioxidant activity (TAA), in both hydrophilic (H-TAA) and lipophilic (L-TAA) fractions. The application of oxalic acid led to lower losses of total phenolics and significant increase in both ascorbic acid content and H-TAA, whereas L-TAA remained unaffected. Thus, oxalic acid could be a promising postharvest treatment to alleviate CI and increase antioxidant potential.