Salicylic-Acid-Regulated Antioxidant Capacity Contributes to Growth Improvement of Okra (Abelmoschus esculentus cv. Red Balady)

The improvement of crop yield and quality are currently of prime concern to achieve global food security and sustainability. Plant elicitation with salicylic acid (SA) has been shown to play a key role in regulating plant growth and productivity. Here, the effects of foliar SA application (1, 2, and 4 mM) on antioxidant capacity and phenolic metabolism, among other biochemical parameters, were studied in okra leaves. The results showed that SA treatments markedly increase the levels of endogenous free SA and trigger the accumulation of chlorophylls, soluble proteins, proline, antioxidant capacity, and phenolic compounds, alongside the stimulation of the enzymatic activities of phenylalanine ammonia-lyase and peroxidase, with these changes being paralleled by decreased levels of lipid peroxidation. The beneficial effects of SA treatments were also tested on field-grown okra plants. Results revealed that yield-associated agronomic attributes significantly increased upon SA treatments, especially at 2 mM SA. Altogether, these results point to a connection between SA-induced antioxidant system strengthening and crop growth and productivity. Therefore, foliar application of SA seems to be a potent and workable approach to enhance okra crop quality and yield.

Potential Importance of Molybdenum Priming to Metabolism and Nutritive Value of Canavalia spp. Sprouts

Molybdenum ions (Mo) can improve plants’ nutritional value primarily by enhancing nitrogenous metabolism. In this study, the comparative effects of seed priming using Mo were evaluated among sproutings of Canavalia species/cultivars, including Canavalia ensiformis var. gladiata (CA1), Canavalia ensiformis var. truncata Ricker (CA2), and Canavalia gladiata var. alba Hisauc (CA3). Mo impacts on growth, metabolism (e.g., nitrogen and phenolic metabolism, pigment and total nutrient profiles), and biological activities were assayed. Principal component analysis (PCA) was used to correlate Mo-mediated impacts. The results showed that Mo induced photosynthetic pigments that resulted in an improvement in growth and increased biomass. The N content was increased 0.3-fold in CA3 and 0.2-fold in CA1 and CA2. Enhanced nitrogen metabolism by Mo provided the precursors for amino acids, protein, and lipid biosynthesis. At the secondary metabolic level, phenolic metabolism-related precursors and enzyme activities were also differentially increased in Canavalia species/cultivars. The observed increase in metabolism resulted in the enhancement of the antioxidant (2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) free radical scavenging, 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP)) and antidiabetic potential (Glycemic index (GI) and inhibition activity of α-amylase, and α-glucosidase) of species. The antioxidant activity increased 20% in CA3, 14% in CA1, and 8% in CA2. Furthermore, PCA showed significant variations not only between Mo-treated and untreated samples but also among Canavalia species. Overall, this study indicated that the sprouts of Canavalia species have tremendous potential for commercial usage due to their high nutritive value, which can be enhanced further with Mo treatment to accomplish the demand for nutritious feed.

Metabolite Analysis of Jerusalem Artichoke (Helianthus tuberosus L.) Seedlings in Response to Polyethylene Glycol-Simulated Drought Stress

Jerusalem artichokes are a perennial crop with high drought tolerance and high value as a raw material to produce biofuels, functional feed, and food. However, there are few comprehensive metabolomic studies on Jerusalem artichokes under drought conditions. Methods: Ultra-performance liquid chromatography and tandem mass spectrometry were used to identify differential metabolites in Jerusalem artichoke seedling leaves under polyethylene glycol (PEG) 6000-simulated drought stress at 0, 18, 24, and 36 h. Results: A total of 661 metabolites and 236 differential metabolites were identified at 0 vs. 18, 18 vs. 24, and 24 vs. 36 h. 146 differential metabolites and 56 common were identified and at 0 vs. 18, 24, and 36 h. Kyoto Encyclopedia of Genes and Genomes enrichment identified 236 differential metabolites involved in the biosynthesis of secondary metabolites and amino acids. Metabolites involved in glycolysis, phenolic metabolism, tricarboxylic cycle, glutamate-mediated proline biosynthesis, urea cycle, amino acid metabolism, unsaturated fatty acid biosynthesis, and the met salvage pathway responded to drought stress. Conclusion: A metabolic network in the leaves of Jerusalem artichokes under drought stress is proposed. These results will improve understanding of the metabolite response to drought stress in Jerusalem artichokes and develop a foundation for breeding drought-resistant varieties.

Bioactive content during the development of the acerola cv. BRS 238 (Frutacor)

The objective of this work was to determine quality, bioactive content and metabolism of vitamin C and phenolic compounds during the development of acerola BRS 238 (Frutacor). Fruits were harvested at five different stages of maturation and evaluated for physical-chemical and chemical quality characteristics, as well as for the metabolism of vitamin C and polyphenols variables. During development, there was an increase in SS/AT ratio, a decrease in chlorophyll content, increase in carotenoids content, and a decline in vitamin C and polyphenols content, alhhtough of yellow flavonoids and anthocyanins content increased. The enzyme activity of vitamin C metabolism, ascorbate oxide (AO) and ascorbate peroxidase (APX) decreased with ripening, while for phenolic metabolism, the activity of phenylalanine ammonia lyase (PAL) increased and polyphenoloxidase (PPO) decreased. It can be concluded that the fruits of aceroleira BRS 238 had a high content of bioactive compounds. For industrial extraction of bioactive compounds, fruits must be harvested at the initial stages, while for fresh consumption, they must be harvested in the final stages of development.

Effect of temperature fluctuation on colour change and softening of postharvest sweet cherry

The inevitable temperature fluctuation induced anthocyanin synthesis, phenolic metabolism, and alkali-soluble pectin degradation, which lead to sweet cherry enzymatic browning and softening.