Biochemical and pharmaceutical traits of Marrubium vulgare L. plants treated with plant growth-promoting bacteria and elevated CO2.

The present research aimed to understand the influence of plant growth-promoting bacteria (PGPB) on various biochemical, nutritional, and pharmaceutical characteristics of Marrubium vulgare plants grown under elevated carbon dioxide (eCO2). To achieve this objective, a pot experiment was carried out, consisting of two treatments, namely: (i) biofertilization (Bf) by a PGPB strain (Micromonospora sp.) and (ii) two different air CO2 levels, including ambient CO2 (aCO2) and eCO2 concentrations (410 and 710 µmol CO2 mol-1, respectively). The improvement in the photosynthesis rate of eCO2 and Bf-treated plants can explain the increase in the production of carbohydrate. This is evidenced by a substantial rise, reaching up to + 75% and 25% in the total sugar and starch content in plants subjected to eCO2 treatment, respectively. Additionally, eCO2-treated plants exhibited a remarkable 102% increase in soluble sugar synthesis, while plants subjected to Bf treatment showed a notable increase of 66%. Such modifications could be the main factor affecting plants carbon and nitrogen metabolism. Although the level of certain amino acids (such as glycine, tyrosine, and phenylalanine) in plants exhibited significant increases in response to eCO2 and Bf, the levels of other amino acids demonstrated enhancements in plants grown under eCO2 (e.g., histidine) or under treatments containing Bf (e.g., alanine and ornithine). Improvements in primary metabolites led to more benefits in plants treated with Bf and CO2 by boosting secondary metabolites accumulation, including phenolics (+ 27-100%), flavonoids (+ 30-92%), and essential oils (up to + 296%), as well as improved antioxidant capacity (FRAP). This remarkable effectiveness was evident in the significant increase in the biomass production, highlighting the synergistic impact of the treatments. Therefore, the interaction of Bf and eCO2 not only induced plant biomass accumulation but also improved the nutritional and pharmaceutical value of M. vulgare plants.

Potassium Nitrate and Ascorbic Acid Priming Improved Tissue Chemical Composition and Antioxidant and Antimicrobial Activities of Linseed (Linum usitatissimum L.) Sprouts.

Potassium nitrate (KNO3) and ascorbic acid (AsA) priming can effectively boost biomass accumulation and nutritional value of plants; nevertheless, few studies investigated their effects on seed sprouting. Thus, we aimed to explore the effects of KNO3 and AsA priming on linseed (Linum usitatissimum L.) sprout growth and assess the changes in bioactive compound levels, which provide valuable insights into the potential benefits of these priming treatments on sprout quality and nutritional value. To this end, germination, biomass accumulation, photosynthetic pigments, primary and secondary metabolites, and mineral profiles in the primed sprouts were evaluated. Moreover, to assess the impact on biological value, we determined the antioxidant and antimicrobial activities of the treated sprout extract. A marked enhancement was observed in germination and pigment levels of KNO3- and AsA-primed sprouts. These increases were in line with induced primary metabolites (e.g., carbohydrate and amino acid contents), particularly under KNO3 treatment. There was also an increase in amino acid metabolism (e.g., increased GS, GDH, and GOGAT enzyme activities), nitrogen level, and nitrate reductase (NR) activity. The linseed sprouts primed with AsA exhibited strong antioxidant and antibacterial activities. Consistently, high levels of polyphenols, flavonoids, total AsA, and tocopherols, as well as improved activity of antioxidant enzymes [peroxidase (POX), catalase (CAT), and superoxide dismutase (SOD)], were recorded. This study proposes KNO3 and AsA priming as an innovative approach to improving the nutritional and health-promoting properties of linseed sprouts. This knowledge will contribute to a better understanding of the biochemical processes involved in improving the nutritional quality and functional benefits of linseed sprouts.

Synergistic Impacts of Plant-Growth-Promoting Bacteria and Selenium Nanoparticles on Improving the Nutritional Value and Biological Activities of Three Cultivars of Brassica Sprouts.

Due to the growing world population and increasing environmental stress, improving the production, nutritional quality, and pharmaceutical applications of plants have become an urgent need. Therefore, current research was designed to investigate the impact of seed priming using plant-growth-promoting bacteria (PGPB) along with selenium nanoparticles (SeNPs) treatment on chemical and biological properties of three Brassica oleracea cultivars [Southern star (VA1), Prominence (VA2), Monotop (VA3)]. With this aim, one out of five morphologically different strains of bacteria, namely, JM18, which was further identified via 16S rRNA gene sequencing as a Nocardiopsis species with strong plant-growth-promoting traits, isolated from soil, was used. To explore the growth-promoting potential of Nocardiopsis species, seeds of three varieties of B. oleracea were primed with JM18 individually or in combination with SeNP treatment. Seed treatments increased sprout growth (fresh and dry weights) and glucosinolate accumulation. The activity of myrosinase was significantly increased through brassica sprouts and consequently enhanced the amino-acid-derived glucosinolate induction. Notably, a reduction in effective sulforaphane nitrile was detected, being positively correlated with a decrease in epithiospecifier protein (EP). Consequently, the antioxidant activities of VA2 and VA3, determined by the ferric reducing antioxidant power (FRAP) assay, were increased by 74 and 79%, respectively. Additionally, the antibacterial activities of JM18-treated cultivars were improved. However, a decrease was observed in SeNP- and JM18 + SeNP-treated VA2 and VA3 against Serratia marcescens and Candida glabrata and VA1 against S. marcescens. In conclusion, seed priming with the JM18 extract is a promising method to enhance the health-promoting activities of B. oleracea sprouts.

The Interaction Effect of Laser Irradiation and 6-Benzylaminopurine Improves the Chemical Composition and Biological Activities of Linseed (Linum usitatissimum) Sprouts.

Even though laser light (LL) and 6-benzylaminopurine (BAP) priming are well-known as promising strategies for increasing the growth and nutritional value of several plants, no previous studies have investigated their synergistic effect. Herein, we investigated the effects of laser light, 6-benzylaminopurine (BAP) priming, and combined LL-BAP treatment on the nutritional value, chemical composition, and the biological activity of Linum usitatissimum sprouts. The fresh weight, leaf pigments, primary and secondary metabolites, enzymes, and antimicrobial activities were determined. A substantial enhancement was observed in the growth characteristics and leaf pigments of laser-irradiated and BAP-primed sprouts. Furthermore, the combined treatments improved the accumulation of minerals, vitamins, and amino acids, and also enhanced the N-metabolism more than LL or BAP alone. Furthermore, the combined priming boosted the antioxidant capacity by increasing the contents of fatty acids, phenols, and flavonoids. Antimicrobial activity and the highest increase in bioactive compounds were recorded in linseed sprouts simultaneously treated with LL and BAP. This work suggests that priming L. usitatissimum sprouts with laser light and BAP is a promising approach that can improve the nutritional value and health-promoting impacts of L. usitatissimum sprouts.