Exogenous naringenin improved digestible protein accumulation and altered morphology via VrPIN and auxin redistribution in Vigna radiata

Comparative analysis of the antibacterial efficacy and bioactive components of Thuja occidentalis obtained from four different geographical sites

The purpose of this study was to determine whether or not there were significant differences in the antibacterial potential of Thuja occidentalis collected from four distinct geographical sites, namely Chamba (Himachal Pradesh, India), Jalandhar (Punjab, India), Aurangabad (Bihar, India) and Kakching (Manipur, India). The plant extracts were prepared in three different solvents: ethanol, methanol, and acetone. The antibacterial potential of the plant extracts was tested against five different bacterial species using well diffusion test. The minimum inhibitory and bactericidal concentrations of the plant sample exhibiting maximum zone of inhibition against different bacterial strains were calculated. Further, the total phenols, flavonoids, and antioxidant efficacy (using DPPH assay) were also analysed biochemically. The activity of different antioxidant enzymes including SOD, CAT and APX were also recorded as these enzymes protect the cells from free radical damage. GC-MS analysis was also performed on all plant extracts to identify the bioactive components. The results showed that the T. occidentalis collected from the Kakching, Manipur, East side of India showed the highest zone of inhibition against all the bacterial strains, followed by Chamba, Jalandhar, and lastly Aurangabad. To analyse the impact of phytochemicals on the antibacterial efficacy, a correlation was drawn between the biochemical parameters and zone of inhibition using Karl Pearson's method. Most bacterial species demonstrated a positive correlation between antibacterial effectiveness (zone of inhibition) and biochemical markers. The GC-MS study revealed positive correlation between zone of inhibition and peak area percentages of α-Pinene, β-caryophyllene, Germacrene-D, and Humulene in all bacterial species indicating that these chemicals may play a key role in the bactericidal potential of T. occidentalis. Based on the results of this investigation, it is evident that the antibacterial effectiveness of T. occidentalis varies with its geographical location which may be attributed to the differences in the phytochemical makeup.

Inhibitory impact of MgO nanoparticles on oxidative stress and other physiological attributes of spinach plant grown under field condition

Green synthesis of NPs is preferred due to its eco-friendly procedures and non-toxic end products. However, unintentional release of NPs can lead to environmental pollution affecting living organisms including plants. NPs accumulation in soil can affect the agricultural sustainability and crop production. In this context, we report the morphological and biochemical response of spinach nanoprimed with MgO-NPs at concentrations, 10, 50, 100, and 150 µg/ml. Nanopriming reduced the spinach root length by 14-26%, as a result a reduction of 20-74% in the length of spinach shoots was observed. The decreased spinach shoot length inhibited the chlorophyll accumulation by 21-55%, thus reducing the accumulation of carbohydrates and yield by 46 and 49%, respectively. The reduced utilization of the total absorbed light further enhanced ROS generation and oxidative stress by 32%, thus significantly altering their antioxidant system. Additionally, a significant variation in the accumulation of flavonoid pathway downstream metabolites myricitin, rutin, kaempferol-3 glycoside, and quercitin was also revealed on MgO-NPs nanopriming. Additionally, NPs enhanced the protein levels of spinach probably as an osmoprotectant to regulate the oxidative stress. However, increased protein precipitable tannins and enhanced oxidative stress reduced the protein digestibility and solubility. Overall, MgO-NPs mediated oxidative stress negatively affected the growth, development, and yield of spinach in fields in a concentration dependent manner.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-023-01391-9.

Advances in the study of the function and mechanism of the action of flavonoids in plants under environmental stresses

MAIN CONCLUSION

This review summarizes the anti-stress effects of flavonoids in plants and highlights its role in the regulation of polar auxin transport and free radical scavenging mechanism. As secondary metabolites widely present in plants, flavonoids play a vital function in plant growth, but also in resistance to stresses. This review introduces the classification, structure and synthetic pathways of flavonoids. The effects of flavonoids in plant stress resistance were enumerated, and the mechanism of flavonoids in plant stress resistance was discussed in detail. It is clarified that plants under stress accumulate flavonoids by regulating the expression of flavonoid synthase genes. It was also determined that the synthesized flavonoids are transported in plants through three pathways: membrane transport proteins, vesicles, and bound to glutathione S-transferase (GST). At the same time, the paper explores that flavonoids regulate polar auxin transport (PAT) by acting on the auxin export carrier PIN-FORMED (PIN) in the form of ATP-binding cassette subfamily B/P-glycoprotein (ABCB/PGP) transporter, which can help plants to respond in a more dominant form to stress. We have demonstrated that the number and location of hydroxyl groups in the structure of flavonoids can determine their free radical scavenging ability and also elucidated the mechanism by which flavonoids exert free radical removal in cells. We also identified flavonoids as signaling molecules to promote rhizobial nodulation and colonization of arbuscular mycorrhizal fungi (AMF) to enhance plant-microbial symbiosis in defense to stresses. Given all this knowledge, we can foresee that the in-depth study of flavonoids will be an essential way to reveal plant tolerance and enhance plant stress resistance.

Molecular mechanism of naringenin regulation on flavonoid biosynthesis to improve the salt tolerance in pigeon pea (Cajanus cajan (Linn.) Millsp.)

Flavonoids are important secondary metabolites in the plant growth and development process. As a medicinal plant, pigeon pea is rich in secondary metabolites. As a flavonoid, there are few studies on the regulation mechanism of naringenin in plant stress resistance. In our study, we found that naringenin can increase the pigeon pea's ability to tolerate salt and influence the changes that occur in flavonoids including naringenin, genistein and biochanin A. We analyzed the transcriptome data after 1 mM naringenin treatment, and identified a total of 13083 differentially expressed genes. By analyzing the metabolic pathways of these differentially expressed genes, we found that these differentially expressed genes were enriched in the metabolic pathways of phenylpropanoid biosynthesis, starch and sucrose metabolism and so on. We focused on the analysis of flavonoid biosynthesis related pathways. Among them, the expression levels of enzyme genes CcIFS, CcCHI and CcCHS in the flavonoid biosynthesis pathway had considerably higher expression levels. By counting the number of transcription factors and the binding sites on the promoter of the enzyme gene, we screened the transcription factors CcMYB62 and CcbHLH35 related to flavonoid metabolism. Among them, CcMYB62 has a higher expression level than the others. The hairy root transgene showed that CcMYB62 could induce the upregulation of CcCHI, and promote the accumulation of naringenin, genistein and biochanin A. Our study revealed the molecular mechanism of naringenin regulating flavonoid biosynthesis under salt stress in pigeon pea, and provided an idea for the role of flavonoids in plant resistance to abiotic stresses.

In vitro exposed magnesium oxide nanoparticles enhanced the growth of legume Macrotyloma uniflorum

Nanoparticles interact with plants to induce a positive, negative, or neutral effect on their growth and development. In this study, we document the positive influence of magnesium oxide (MgO) nanoparticles (NPs) on the morpho-biochemical parameters of Macrotyloma uniflorum (horse gram). Horse gram is a protein and polyphenol-rich legume crop. It is an important part of the human diet and nutrition. When exposed to MgO-NPs, a significant increment in the shoot-root length, fresh biomass, and chlorophyll content of horse gram was evident. Furthermore, there was a 4-20 and 18-127% increase in the accumulation of carbohydrate and protein content on MgO-NP exposure. The antioxidant potential was enhanced by 5-19% on NP treatment as a result of the increase in the accumulation of total polyphenolics. Total phenols and flavonoids were enhanced by 7-20 and 50-84% in the presence of MgO-NPs. The enzyme activity of SOD, CAT, and APX was also enhanced in MgO-NP-exposed horse gram. The observed alterations were also justified by the Pearson correlation. Overall, the MgO-NP-induced morpho-biochemical alterations in horse gram indicated their probable role as a nano-fertilizer. However, it further warrants the need to extensively investigate the responses of various other plant types to MgO-NPs before industry scale application.