Characterization and metabolomics profiling of Kappaphycus alvarezii seaweed extract

Plant nutrition challenges for a sustainable agriculture of the future

This article offers a comprehensive review of sustainable plant nutrition concepts, examining a multitude of cutting-edge techniques that are revolutionizing the modern area. The review copes with the crucial role of biostimulants as products that stimulate plant nutrition processes, including their potential for biofertilization, followed by an exploration of the significance of micronutrients in plant health and growth. We then delve into strategies for enhancing plants' tolerance to mineral nutrient contaminants and the promising realm of biofortification to increase the essential nutrients necessary for human health. Furthermore, this work also provides a concise overview of the burgeoning field of nanotechnologies in fertilization, while the integration of circular economy principles underscores the importance of sustainable resource management. Then, with examined the interrelation between micronutrients. We conclude with the future challenges and opportunities that lie ahead in the pursuit of more sustainable and resilient plant systems.

A red seaweed Kappaphycus alvarezii-based biostimulant (AgroGain®) improves the growth of Zea mays and impacts agricultural sustainability by beneficially priming rhizosphere soil microbial community

The overuse of chemical-based agricultural inputs has led to the degradation of soil with associated adverse effects on soil attributes and microbial population. This scenario leads to poor soil health and is reportedly on the rise globally. Additionally, chemical fertilizers pose serious risks to the ecosystem and human health. In this study, foliar sprays of biostimulant (AgroGain/LBS6) prepared from the cultivated, tropical red seaweed Kappaphycus alvarezii increased the phenotypic growth of Zea mays in terms of greater leaf area, total plant height, and shoot fresh and dry weights. In addition, LBS6 improved the accumulation of chlorophyll a and b, total carotenoids, total soluble sugars, amino acids, flavonoids, and phenolics in the treated plants. LBS6 applications also improved the total bacterial and fungal count in rhizospheric soil. The V3-V4 region of 16S rRNA gene from the soil metagenome was analyzed to study the abundance of bacterial communities which were increased in the rhizosphere of LBS6-treated plants. Treatments were found to enrich beneficial soil bacteria, i.e., Proteobacteria, especially the classes Alphaproteobacteria, Cyanobacteria, Firmicutes, Actinobacteriota, Verrucomicrobiota, Chloroflexi, and Acidobacteriota and several other phyla related to plant growth promotion. A metagenomic study of those soil samples from LBS6-sprayed plants was correlated with functional potential of soil microbiota. Enrichment of metabolisms such as nitrogen, sulfur, phosphorous, plant defense, amino acid, co-factors, and vitamins was observed in soils grown with LBS6-sprayed plants. These results were further confirmed by a significant increase in the activity of soil enzymes such as urease, acid phosphatase, FDAse, dehydrogenase, catalase, and biological index of fertility in the rhizosphere of LBS6-treated corn plant. These findings conclude that the foliar application of LBS6 on Z. mays improves and recruits beneficial microbes and alters soil ecology in a sustainable manner.

From Ocean to Medicine: Harnessing Seaweed's Potential for Drug Development

Seaweed, a miscellaneous group of marine algae, has long been recognized for its rich nutritional composition and bioactive compounds, being considered nutraceutical ingredient. This revision delves into the promising role of seaweed-derived nutrients as a beneficial resource for drug discovery and innovative product development. Seaweeds are abundant sources of essential vitamins, minerals, polysaccharides, polyphenols, and unique secondary metabolites, which reveal a wide range of biological activities. These bioactive compounds possess potential therapeutic properties, making them intriguing candidates for drug leads in various medical applications and pharmaceutical drug development. It explores their pharmacological properties, including antioxidant, anti-inflammatory, antimicrobial, and anticancer activities, shedding light on their potential as therapeutic agents. Moreover, the manuscript provides insights into the development of formulation strategies and delivery systems to enhance the bioavailability and stability of seaweed-derived compounds. The manuscript also discusses the challenges and opportunities associated with the integration of seaweed-based nutrients into the pharmaceutical and nutraceutical industries. Regulatory considerations, sustainability, and scalability of sustainable seaweed sourcing and cultivation methods are addressed, emphasizing the need for a holistic approach in harnessing seaweed's potential. This revision underscores the immense potential of seaweed-derived compounds as a valuable reservoir for drug leads and product development. By bridging the gap between marine biology, pharmacology, and product formulation, this research contributes to the critical advancement of sustainable and innovative solutions in the pharmaceutical and nutraceutical sectors.

Underpinning beneficial maize response to application of minimally processed homogenates of red and brown seaweeds

Sap from the fresh seaweed Kappaphycus alvarezii (KA) has been reported to improve crop growth, quality, and stress alleviation. However, limited studies are reported for the minimally processed aqueous homogenates (MPHs) derived from dry seaweeds. The present investigation was envisaged to characterize the MPHs from the red seaweed KA and a brown seaweed Sargassum wightii (SW) and also assess the effect of foliar application on maize (Zea mays) crop performance when applied alone or in proportions ranging from 0% to 100%. Two doses (0.35% and 0.7%) were compared with control. Both the MPHs contained several compounds like retronecine, tyrosyl-glycine, hexyl 2-furoate, 1-phosphatidyl-1D-myo-inositol, 12-(2,3-dihydroxycyclopentyl)-2-dodecanone, and trihomomethionine and many others that have known bioactivity for enhancing plant growth and providing stress tolerance. Both doses of MPHs enhanced crop growth and yield; however, the best response was in general observed at a lower dose. The MPH of SW at 100% gave the highest seed yield at a lower dose, which was also on par with that obtained under a lower dose of 100% KA. Other combinations, 80:20 and 40:60 KA : SW, were also found to give comparable yields. The highest dose of 100% MPH of SW was found on par with control, a phenomenon that was investigated in detail with respect to metabolites and antioxidant profile in leaves as well as membrane modeling. Higher ROS and certain sugar and organic acids were observed in 100% MPH of SW at a higher dose, although none of the antioxidant enzymes were significantly affected, nor was there any change in membrane characteristics of the leaf with respect to control as well as lower dose. Improvements in the seed yield were attributed to improved photosynthate production on account of higher dry matter accumulation in the MPH-treated plants, which may also be attributed to the presence of bioactive compounds in the biostimulants. In the future, it is imperative to direct scientific investigations towards the quantification and identification of the most effective concentrations of these compounds within MPHs to optimize plant responses. The study indicated the beneficial use of the MPHs towards increasing crop production by employing optimum dose as foliar spray to crops.

Valorization of Kappaphycus alvarezii through extraction of high-value compounds employing green approaches and assessment of the therapeutic potential of κ-carrageenan

This study utilizes different emerging green extraction technologies to recover maximum value-added products from Kappaphycus alvarezii and evaluate their bio-functional properties. Using the supercritical fluid extraction (SFE) method, the total lipid yield of 0.21 ± 0.2 % was obtained from the biomass. Linoleic acid, eicosapentaenoic acid, arachidonic acid, γ-linolenic acid, and docosahexaenoic acid were present in higher concentrations (9.12 %) in the lipid extracted with SFE as compared to hexane (5.5 %). Using an ultrasonication assisted approach, ~56 % of κ-carrageenan was recovered from SFE residual biomass, which contains 28.5 ± 1.9 % sulfate content. It exhibited a monosaccharide content of 3,6-anhydrogalactose (~24 %) and galactose (~53 %), as well as rheological properties within FAO limitations that can be explored for food-grade applications. ~58 % of the total protein (12.5 %) from SFE residual biomass was recovered using subcritical water hydrolysis method. The effectiveness of κ-carrageenan in suppressing the 3CLpro of SARS-CoV-2 using in vitro and in silico approaches was investigated. κ-Carrageenan effectively inhibited the main protease by up to 93 % at 1.6 mg mL-1. In silico results revealed that κ-carrageenan successfully binds to the active site of the main protease while retaining the structural integrity and stability of protein-ligand complexes.

Phytochemical Constituents, Antimicrobial Properties and Bioactivity of Marine Red Seaweed (Kappaphycus alvarezii) and Seagrass (Cymodocea serrulata)

The present work was performed to evaluate the levels of phytochemical constituents and the antioxidant and antibacterial properties of marine red seaweed (Kappaphycus alvarezii) and seagrass (Cymodocea serrulata). Quantitative phytochemical analysis, antioxidant activity and antimicrobial activity against five potential pathogenic bacteria was investigated. In each case, we found the presence of flavonoids, tannins, phenolic compounds, glycosides, steroids, carbohydrates and ashes. Alkaloids were only found in K. alvarezii, though they were not found in C. serrulata. The antimicrobial properties of both K. alvarezii and C. serrulata chloroform extracts were found to be antagonistically effective against the Gram-positive bacteria Bacillus subtilis and the Gram-negative bacteria Vibrio parahaemolyticus, Vibrio alginolyticus, Vibrio harveyi and Klebsiella pneumoniae. GC-MS analysis revealed the presence of 94 bioactive compounds in K. alvarezii and 104 bioactive compounds in C. serrulata, including phenol, decane, dodecane, hexadecane, vanillin, heptadecane, diphenylamine, benzophenone, octadecanoic acid, dotriaconate, benzene, phytol, butanoic acid and 2-hydroxyl-ethyl ether, which all played important roles in antioxidant and antibacterial activities. Thus, in view of the results, both K. alvarezii and C. serrulata could be considered to be sources of ingredients with appreciable nutritional and medicinal value.

Biostimulant enhances growth and corm production of saffron (Crocus sativus L.) in non-traditional areas of North western Himalayas

The usage of seaweed extracts in cropping systems is gaining attention nowadays due to their distinct bioactive properties. This study aims to assess how saffron (Crocus sativus L.) corm production was affected by seaweed extract through different application modes. The study was conducted at the CSIR-Institute of Himalayan Bioresource Technology, Palampur, HP, India, during the autumn-winter agricultural cycle. Five treatments using a combination of Kappaphycus and Sargassum seaweed extracts were replicated five times in a randomized block design. Treatments that were examined include T1: Control, T2: Corm dipping @ 5% seaweed extract, T3: Foliar spray @ 5% seaweed extract, T4: Drenching @ 5% seaweed extract, and T5: Corm dipping + foliar spray @ 5% seaweed extract. Seaweed extract, when applied to saffron plants (T5: Corm dipping + foliar spray @ 5% seaweed extract) resulted in significantly higher growth parameters along with the higher dry weight of stem, leaves, corms, and total roots per corm. Corm production, viz., the number of daughter corms and corm weight per m² was significantly affected by seaweed extract application, with the maximum value recorded with treatment T5. Biochemical parameters chlorophyll, carotenoids, and photosynthetic rate were higher in T5, while nutrient concentration was lowest in this treatment. Seaweed extracts improved corm production, making it a feasible alternative to limiting the application of conventional fertilizers, attenuating the effects on the environment, and enhancing corm number and weight.

Understanding the mode of action of AgroGain®, a biostimulant derived from the red seaweed Kappaphycus alvarezii in the stimulation of cotyledon expansion and growth of Cucumis sativa (cucumber)

Seaweed-based biostimulants are sustainable agriculture inputs that are known to have a multitude of beneficial effects on plant growth and productivity. This study demonstrates that Agrogain^® (Product code: LBS6), a Kappaphycus alvarezii-derived biostimulant induced the expansion of cucumber cotyledons. Seven days treatment of LBS6-supplementation showed a 29.2% increase in area of expanded cotyledons, as compared to the control. LBS6-treated cotyledons also showed higher amylase activity, suggesting starch to sucrose conversion was used efficiently as an energy source during expansion. To understand the mechanisms of LBS6-induced expansion, real time gene expression analysis was carried out. This revealed that LBS6-treated cotyledons differentially modulated the expression of genes involved in cell division, cell number, cell expansion and cell size. LBS6 treatment also differentially regulated the expression of those genes involved in auxin and cytokinin metabolism. Further, foliar application of LBS6 on cucumber plants being grown under hydroponic conditions showed improved plant growth as compared to the control. The total leaf area of LBS6-sprayed plants increased by 19.1%, as compared to control. LBS6-sprayed plants efficiently regulated photosynthetic quenching by reducing loss via non-photochemical and non-regulatory quenching. LBS6 applications also modulated changes in the steady-state photosynthetic parameters of the cucumber leaves. It was demonstrated that LBS6 treatment modulated the electron and proton transport related pathways which help plants to efficiently utilize the photosynthetic radiation for optimal growth. These results provide clear evidence that bioactive compounds present in LBS6 improved the growth of cucumber plants by regulating the physiological as well as developmental pathways.

Cleaner production technologies for the amelioration of soil health, biomass and secondary metabolites in Ocimum basilicum L. under Indian Western Himalaya

Ocimum basilicum L. and its derived products are primarily consumed by humans; hence, agrochemical use seems inappropriate for its cultivation. However, farmers are accustomed to using rampant inorganic fertilizers to augment crop productivity, which has unintendedly engendered severe environmental perturbations. Concomitantly, farmers will soon have to confront the challenges of growing crops under suboptimal conditions driven by global climate change. Consequently, to develop a clean, sustainable, and resilient production technology, field experiments spanning over two years (2020 and 2021) were conducted, comprising three biostimulants, viz., vermicompost (0, 4, and 8 Mg ha^-1), biofertilizer (uninoculated and inoculated), and liquid seaweed extract (without and at 7 ml L^-1) in the Indian western Himalaya for the first time. Soil health indicators, leaf photosynthetic pigments, gaseous exchange, mineral contents, essential oil (EO) quantity, and composition were evaluated. Soil microbial respiration (SMR), microbial biomass carbon (MBC), organic carbon (OC), dehydrogenase (DHA), alkaline phosphatase (ALP), and β-glucosidase activities were increased by 36.23, 83.98, 30.61, 42.69, 34.00, and 40.57%, respectively, when compared with the initial soil status. The net photosynthetic rate (Pn) was significantly increased with the highest (8 Mg ha^-1) and moderate (4 Mg ha^-1) vermicompost dosages by 13.96% and 4.56%, respectively, as compared with the unfertilized control (0 Mg ha^-1). Likewise, the biofertilizer and seaweed extract also enhanced Pn by 15.09% and 10.09%, respectively. The crop's key EO constituents, viz., methyl chavicol and linalool, were significantly improved with the highest and moderate vermicompost rates of 2.71, 9.85%, and 1.18, 5.03%, respectively. Similarly, biofertilization and seaweed application also boosted methyl chavicol and linalool by 3.29, 8.67%, and 1.93, 3.66%, respectively. In both years, significantly higher herbage (8.86 and 11.25 Mg ha^-1) and EO yield (113.78 and 154.87 kg ha^-1) were recorded with a congregate treatment of the highest vermicompost dose, biofertilizer, and liquid seaweed extract. In conclusion, the integrated use of biostimulants having complementary properties can sustainably maximize the quantity and quality of O. basilicum and concomitantly ameliorate soil health. This study can inspire scientific communities and industries to develop second-generation biostimulant products, delivering better sustainability and resilience for a renaissance in agriculture.

R, Choudhary AK, Salam MD, Sahoo MR, Bhutia TL, Devi SH, Thounaojam AS, Behera C, M. N. H, Kumar A, Dasgupta M, Devi YP, Singh D, Bhagowati S, Devi CP, Singh HR, Khaba CI. Role of biostimulants in mitigating the effects of climate change on crop performance

Climate change is a critical yield-limiting factor that has threatened the entire global crop production system in the present scenario. The use of biostimulants in agriculture has shown tremendous potential in combating climate change-induced stresses such as drought, salinity, temperature stress, etc. Biostimulants are organic compounds, microbes, or amalgamation of both that could regulate plant growth behavior through molecular alteration and physiological, biochemical, and anatomical modulations. Their nature is diverse due to the varying composition of bioactive compounds, and they function through various modes of action. To generate a successful biostimulatory action on crops under different parameters, a multi-omics approach would be beneficial to identify or predict its outcome comprehensively. The 'omics' approach has greatly helped us to understand the mode of action of biostimulants on plants at cellular levels. Biostimulants acting as a messenger in signal transduction resembling phytohormones and other chemical compounds and their cross-talk in various abiotic stresses help us design future crop management under changing climate, thus, sustaining food security with finite natural resources. This review article elucidates the strategic potential and prospects of biostimulants in mitigating the adverse impacts of harsh environmental conditions on plants.