RBOH-dependent signaling is involved in He-Ne laser-induced salt tolerance and production of rosmarinic acid and carnosol in Salvia officinalis

Low-intensity laser exposure enhances rice (Oryza sativa L.) growth through physio-biochemical regulation, transcriptional modulation, and microbiome alteration

Environmental stressors significantly impact plant growth and agricultural productivity, necessitating innovative approaches to enhance crop resilience and yield. While high-intensity laser applications in agriculture have traditionally been limited to destructive purposes due to their harmful effects on plant growth, the emergence of low-intensity laser technology presents new opportunities for crop improvement. However, the molecular mechanisms underlying the beneficial effects of low-intensity laser treatment remain largely unexplored. This study investigated the effects of low-intensity laser treatment on rice seedling growth, physiological and molecular responses, and rhizosphere microbial communities. Low-intensity laser treatment (2 µmol/m²/s PPFD) significantly enhanced root and shoot growth, enhanced biomass accumulation, and improved yield parameters, with a 16.8% increase in effective panicles and 9.01% higher yield per plant. Physiological analyses revealed elevated antioxidant enzyme activities (POD and SOD) and reduced ROS levels in treated plants. Transmission electron microscopy showed improved chloroplast structure, correlating with enhanced photosynthetic efficiency. Transcriptomic analysis identified 623 differentially expressed genes, with significant enrichment in pathways related to photosynthesis, carbon metabolism, and hormone signaling. Notably upregulation was observed in photosynthesis-related genes (OsPsbB and OsCYF) and hormone signaling genes (OsWRKY114 and OsWRI1). Additionally, 16S rRNA sequencing revealed significant restructuring of rhizosphere bacterial communities in laser-treated plants, with enrichment of beneficial genera including Pseudomonas and Enterobacter. These findings establish low-intensity laser treatment as a promising tool for enhancing rice productivity through coordinated regulation of photosynthetic efficiency, stress responses, and beneficial microbiome interactions.

Red light induced seed germination and seedling growth by modulating antioxidant defense system, Rubisco, and NADPH oxidase activities in Capsicum frutescens

In this study, the impact of light-emitting diodes (LEDs) in different spectrums was investigated on the seed germination and post-germinative performance of Capsicum frutescens seedlings. The seeds were exposed to different LED lights (full spectrum, white, red, blue, and red-blue) for 0, 1, 2, and 4 h (h). The seeds were placed for a week in darkness to investigate germination, and then the growth mechanisms were studied in four-week-old seedlings. Results indicated that germination percentage was promoted markedly under 2 h red and full lights and also in 1 h blue, which was accompanied by the regulation of H2O2 level and NADPH oxidase (NOX) activity. Sprout growth and height were more heightened under 2 h red light, but their contents decreased considerably under blue light with a rising incubation time. Red light induced more biomass yield, chlorophyll (Chl) pigments, Chl a/b ratio and florescence in four-week-old seedlings. Blue light also increased Chl pigments, but decreased biomass yield by enhancing malondialdehyde (MDA) level. Increased growth in seedlings treated to red light was associated with upregulating Rubisco gene expressions (rbcL and rbcS) and its activity. Red and red-blue lights promoted the activity of superoxide dismutase, glutathione reductase, and ascorbate peroxidase enzymes to increase ascorbic acid (ASA) production in the ascorbate-glutathione cycle. Total phenolic (0.22 mg DAG g- 1 DW), ASA (89.58 mg 100 g- 1 FW) and capsaicinoids (2.73 mg g- 1 DW) contents were heightened under red light, while carotenoid (11.78 µg g- 1 FW) content was more accumulated under blue light. The findings of this study suggest red light modulates NOX activity and H2O2 level for inducing seed germination and seedling quality in C. frutescens, which can create important implications for the production of antioxidant metabolites and increase the cultivation area of this plant.

Elite genotype selection through antioxidant and antimicrobial activities, in vitro multiplication with meta-Topolin, genetic fidelity assessment via SCoT markers and cytological study, and chemo-profiling of selected elite genotype of Solanum sisymbriifolium Lam.: an underutilized alternative for nutrition and medicine

Nowadays, the increasing world population and antibiotic resistance have become globally concerning issues. Solanum sisymbriifolium Lam. is an underexploited plant with multipurpose therapeutic and culinary uses and can be utilized as an alternative source of food and medicine. In this study, an elite genotype selection program of S. sisymbriifolium (SS) has been conducted with ten different collections from five agro-geochemical regions of West Bengal, India, based on the antioxidant properties and antimicrobial activity against multi-drug-resistant (MDR) clinical isolates. The SS 5 genotype has shown the best antioxidant activity in DPPH (299.09 μg/ml), ABTS (140.84 μg/ml), and FRAP (10.63 mg ascorbic acid equivalent/g DW) assays and simultaneously performed best against the MDR pathogenic bacteria, producing maximum zone of inhibition (19.67 ± 0.33 mm) against Morganella morganii. Therefore, the SS 5 genotype was chosen as elite type, and mass propagated in in vitro condition. Best shoot multiplication (14.06 ± 0.11) was observed in MS media containing 0.2 mg/l thidiazuron and 0.2 mg/l meta-Topolin. The ex vitro established plants were found to be cytogenetically stable with mother plant following assessment using start codon targeted (SCoT) markers and cytological study (2n = 24). The ex vitro plants were also analyzed for seven different phenolic acids (03.30-121.75 µg/g DW) and four vitamin B (04.38-22.29 mg/100 g FW) contents and found to be phytochemically stable with mother plant as well. Thus, this study validates the pharmacological and nutritional importance of this underutilized species S. sisymbriifolium, and the plant can be commercially exploited using the reproducible protocols provided in this study.

Seed laser priming enhances defensive responses in milk thistle under Pb toxicity

Heavy metal stress negatively affects the growth of medicinal plants. While the effects of Helium-Neon (He-Ne) laser on seed germination and stress tolerance in plants has garnered significant attention, little is known concerning the impacts of He-Ne laser irradiation on heavy metal tolerance in plants. Therefore, the current study was conducted to appraise the effect of different durations (0, 20, and 40 min) of seed priming with He-Ne laser (10 mW mm-2) on the antioxidant system of Silybum marianum L. plants under various Pb concentrations (0, 250, and 500 ppm). Lead phytotoxicity was evident by significant reductions in fresh and dry weights of shoots and roots, total chlorophyll (TChl) content and relative water content (RWC), as well as increases in H2O2 and malondialdehyde contents in roots and leaves. Seed irradiation with He-Ne laser for 20 min significantly improved these parameters, enhancing Pb tolerance. Conversely, the prolonged laser priming (40 min) resulted in less favorable outcomes, including reduced growth, TChl content, and RWC, while also exacerbating oxidative damage to membranes even under non-stressful conditions. The 20-min laser priming systemically mitigated Pb-induced lipid peroxidation and H2O2 accumulation by boosting the activities of superoxide dismutase and catalase and increasing proline content in leaves and roots of milk thistle plants. These findings and multivariate analysis suggest that optimal dose of laser initiates a "stress memory" in seeds which is activated upon subsequent exposure to Pb stress, boosting the plant defensive mechanisms and enabling the plant to better cope with oxidative damage. This study underscore the promising potential of He-Ne laser priming as a novel strategy for increasing heavy metal tolerance in medicinal plants like milk thistle, offering an eco-friendly technique for maintaining their productivity under heavy metal stress.

Exogenous Calcium Enhances Castor Tolerance to Saline-Alkaline Stress by Regulating Antioxidant Enzyme Activity and Activating Ca2+ and ROS Signaling Crosstalk

Saline-alkaline stress is a major factor limiting agricultural development, with calcium (Ca2+) playing a role in regulating plant tolerance through multiple signaling pathways. However, the specific mechanisms by which Ca2+ mediates saline-alkaline stress tolerance at the molecular level remain incompletely understood. This study investigates the effects of exogenous Ca2+ application on enhancing plant tolerance to saline-alkaline stress, focusing on its impact on the antioxidant system and Ca2+ and reactive oxygen species (ROS) signaling pathways. Through physiological assays and transcriptomic analyses, we evaluated oxidative damage markers, antioxidant enzyme activities, and the expression of key Ca2+ and ROS signaling genes. The results showed that saline-alkaline stress significantly elevated ROS levels, which led to increased membrane lipid peroxidation and induced upregulation of antioxidant response elements in castor roots. Exogenous calcium treatment reduced ROS accumulation by increasing superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities and decreasing malondialdehyde (MDA) levels, demonstrating a marked improvement in the antioxidant system. Transcriptomic analysis identified CAT2 (LOC107261240) as the primary target gene associated with increased CAT activity in response to exogenous calcium. Additionally, the upregulation of specific Ca2+ channels, Ca2+ sensors, ROS receptors, and antioxidant-related genes with calcium treatment highlights the critical role of Ca2+-ROS signaling crosstalk in enhancing stress tolerance. Protein-protein interaction analysis identified APX3 and other hub genes involved in Ca2+-ROS signaling transduction and the regulation of antioxidant activity. These findings enhance our understanding of calcium's complex regulatory roles in plant abiotic stress responses, offering new theoretical insights for improving crop resilience in agriculture.