Carrageenans as biostimulants and bio-elicitors: plant growth and defense responses.

In the context of climate change, the need to ensure food security and safety has taken center stage. Chemical fertilizers and pesticides are traditionally used to achieve higher plant productivity and improved plant protection from biotic stresses. However, the widespread use of fertilizers and pesticides has led to significant risks to human health and the environment, which are further compounded by the emissions of greenhouse gases during fertilizer and pesticide production and application, contributing to global warming and climate change. The naturally occurring sulfated linear polysaccharides obtained from edible red seaweeds (Rhodophyta), carrageenans, could offer climate-friendly substitutes for these inputs due to their bi-functional activities. Carrageenans and their derivatives, known as oligo-carrageenans, facilitate plant growth through a multitude of metabolic courses, including chlorophyll metabolism, carbon fixation, photosynthesis, protein synthesis, secondary metabolite generation, and detoxification of reactive oxygen species. In parallel, these compounds suppress pathogens by their direct antimicrobial activities and/or improve plant resilience against pathogens by modulating biochemical changes via salicylate (SA) and/or jasmonate (JA) and ethylene (ET) signaling pathways, resulting in increased production of secondary metabolites, defense-related proteins, and antioxidants. The present review summarizes the usage of carrageenans for increasing plant development and defense responses to pathogenic challenges under climate change. In addition, the current state of knowledge regarding molecular mechanisms and metabolic alterations in plants during carrageenan-stimulated plant growth and plant disease defense responses has been discussed. This evaluation will highlight the potential use of these new biostimulants in increasing agricultural productivity under climate change.

Unraveling Tamarindus indica Pulp-Derived Green Magnesium Oxide Nanoparticles for Cardioprotective Potential against Doxorubicin-Induced Cardiomyopathy: A Comprehensive Biochemical and Gene Expression Study.

The present work investigates a sustainable approach to synthesize magnesium oxide nanoparticles (MgO NPs) using an aqueous pulp extract derived from Tamarindus indica. The effective synthesis of MgO NPs was verified by characterizing methods such as UV-vis spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX). These nanoparticles possess small crystallite sizes, distinctive surface shapes, specific elemental compositions, and stabilizing and encapsulating constituents. Furthermore, total phenolic content (TPC) and total flavonoid content (TFC) tests revealed the existence of phytochemical components in MgO NPs. Significantly, these MgO NPs demonstrated exceptional antioxidant capabilities, as evidenced by their strong performance in antioxidant assays such as 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), nitric oxide (NO) scavenging, and iron chelation tests. They also exhibited a notable ability to inhibit red blood cell (RBC) hemolysis and lipid peroxidation. In toxicity assessments using Baby Hamster Kidney fibroblasts (BHK-21) and Vero cell lines, the MgO NPs displayed a safe profile. Additionally, in vivo studies on Doxorubicin (DOX)-induced cardiotoxicity revealed the cardioprotective properties of these NPs, accompanied by a detailed understanding of the underlying mechanisms. Pretreatment with MgO NPs effectively countered DOX-induced alterations in cardiac biomarkers, lipid profiles, cardiac enzymes, and lipid peroxidation. Furthermore, they modulated apoptosis-related markers (caspase-3 and p53), upregulated antiapoptotic (Bcl-2), and antioxidant (SOD) markers, suggesting their potential therapeutic value in addressing DOX-induced cardiomyopathy. In conclusion, this study underscores the promising cardioprotective, hypolipidemic, antioxidant, and antiapoptotic qualities of MgO NPs derived from tamarind pulp, offering valuable insights into their therapeutic applications and underlying biological mechanisms.

Sclerotinia sclerotiorum (Lib.) de Bary: Insights into the Pathogenomic Features of a Global Pathogen.

Sclerotinia sclerotiorum (Lib.) de Bary is a broad host-range fungus that infects an inclusive array of plant species and afflicts significant yield losses globally. Despite being a notorious pathogen, it has an uncomplicated life cycle consisting of either basal infection from myceliogenically germinated sclerotia or aerial infection from ascospores of carpogenically germinated sclerotia. This fungus is unique among necrotrophic pathogens in that it inevitably colonizes aging tissues to initiate an infection, where a saprophytic stage follows the pathogenic phase. The release of cell wall-degrading enzymes, oxalic acid, and effector proteins are considered critical virulence factors necessary for the effective pathogenesis of S. sclerotiorum. Nevertheless, the molecular basis of S. sclerotiorum pathogenesis is still imprecise and remains a topic of continuing research. Previous comprehensive sequencing of the S. sclerotiorum genome has revealed new insights into its genome organization and provided a deeper comprehension of the sophisticated processes involved in its growth, development, and virulence. This review focuses on the genetic and genomic aspects of fungal biology and molecular pathogenicity to summarize current knowledge of the processes utilized by S. sclerotiorum to parasitize its hosts. Understanding the molecular mechanisms regulating the infection process of S. sclerotiorum will contribute to devising strategies for preventing infections caused by this destructive pathogen.

Biosynthesized magnesium oxide nanoparticles from Tamarindus indica seed attenuate doxorubicin-induced cardiotoxicity by regulating biochemical indexes and linked genes.

The phytochemicals of Tamarindus indica seed hydroalcoholic extract were exploited as a biocatalyst for the sustainable synthesis of magnesium oxide nanoparticles (MgO-NPs). This research investigated the cardioprotective effects of biosynthesized magnesium oxide nanoparticle (MgO-NPs). The biosynthesized seed MgO-NPs were characterized by ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy-dispersive X-ray diffraction (EDX), and Fourier-transform infrared spectroscopy (FT-IR). These methodological approaches demonstrated their capacity to synthesize crystalline and aggregated MgO-NPs with a size average of 13.38 ± 0.16 nm. The biogenic MgO-NPs were found to have a significant quantity of total phenolic contents (TPC) and total flavonoid contents (TFC), indicating the existence of phenol and flavonoid-like components. The biogenic MgO-NPs demonstrated a significant free radical scavenging effects compared to different standards as measured by the inhibition of free radicals produced in 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS•+), and Nitric oxide (NO) scavenging methods; they also exhibited higher ferric ion reducing capacity in FRAP assay. Moreover, they were found to be non-toxic in cytotoxic assessment. Pretreatment of Wistar Albino rats with seed MgO-NPs resulted in a significant reduction of cardiac biomarkers, i.e., cardiac Troponin-I (cTnI), creatine kinase (CK-MB), and aspartate aminotransferase (AST). The seed MgO-NPs were more successful in reducing lipid levels. The results of the mRNA expression analysis showed that seed MgO-NPs efficiently reduced the expression of the apoptotic genes p53 and Caspase-3 while restoring the expected levels of SOD gene expression. The histopathological observations were primarily focused on the disruption of cardiac fibers and myofibrillar disintegration, which are consistent with the biochemical findings. Therefore, our research suggests that MgO-NPs derived from the seeds of Tamarindus indica as a powerful antioxidant; the administration may be effective in protecting the heart from DOX-induced cardiotoxicity.

The Protective Effect of Lasia spinosa (Linn.) Dissipates Chemical-Induced Cardiotoxicity in an Animal Model.

Lasia spinosa (L.) Thwaites is a medicinal plant of enormous traditional use with insufficient scientific evidence. This research screened the antioxidative effect of L. spinosa extracts by measuring the total phenolic content, total flavonoid content, DPPH free radical scavenging activity, ABTS scavenging activity, Iron-chelating activity, and Ferric reducing power followed by an evaluation of in vivo cardioprotective effect in doxorubicin-induced Wistar Albino rats. Phytochemical characterization was made by Gas Chromatography-Mass Spectroscopic analysis. L. spinosa showed an excellent antioxidative effect while methanol leaf extract (LSM) was found to be more potent than ethyl acetate leaf extract (LSE) in scavenging the free radicals. Intraperitoneal injection of doxorubicin caused a significant (P < 0.001) increase in lactate dehydrogenase (LDH), creatine kinase (CK-MB), C-reactive protein (CRP), and Cardiac troponin I. Pretreatment with orally administrated (LSM100 and LSM200 mg/kg b.w.) daily for 10 days showed a decrease in the cardiac markers, lipid profiles, especially triglycerides (TG), total cholesterol (TC), low-density lipoprotein (LDL), and an increase of high-density lipoprotein (HDL) compared to the disease control group. LSM200 was found to significantly (P < 0.05) decrease the levels of CK-MB and LDH. It also restored TC, TG, and LDL levels compared to the doxorubicin-induced cardiac control group. The protective role of LSM was further confirmed by histopathological examination. This study thus demonstrates that L. spinosa methanol extract could be approached as an alternative supplement for cardiotoxicity, especially in the chemical-induced toxicity of cardiac tissues.

Understanding Phakopsora pachyrhizi in soybean: comprehensive insights, threats, and interventions from the Asian perspective.

Soybean (Glycine max L.) is an important crop in Asia, accounting for 17% of global soybean cultivation. However, this crop faces formidable challenges from the devastating foliar disease, Asian Soybean Rust (ASR), caused by Phakopsora pachyrhizi, a biotrophic fungus with a broad host range, causing substantial yield losses (10-100%) in Asia. This comprehensive review consolidates knowledge on ASR, encompassing its impact, historical perspectives, genetic diversity, epidemic drivers, early detection, risk assessment, and sustainable management strategies of ASR in the region. ASR has expanded globally from Asia, reaching Africa and Americas, driven by wind-dispersed urediniospores. Genetic diversity studies reveal the complexity of P. pachyrhizi, with distinct populations exhibiting varying virulence patterns. Factors affecting ASR epidemics in Asia include host susceptibility, landscape connectivity, climate, and environmental conditions. Understanding the interplay of these factors is essential for early intervention and control of ASR in soybean fields. Effectively managing ASR can exploit the utilization of diverse intervention strategies, encompassing disease forecasting, automated early detection, disease resistance, fungicide application, and biological control. A pivotal aspect of successful, sustainable disease management lies in reducing the ASR pathogen virulence and preventing it from developing fungicide resistance, while the highpoint of effectiveness in disease control is attained through a synergistic approach, integrating various strategies. In summary, this comprehensive review provides insights into multifaceted approaches that contribute to the development of sustainable and economically impactful soybean production in the face of the persistent threat of ASR in Asia.

Assessing the potentials of bacterial antagonists for plant growth promotion, nutrient acquisition, and biological control of Southern blight disease in tomato.

Southern blight of tomato caused by Sclerotium rolfsii can cause severe plant mortality and yield losses. The use of rhizobacteria for the biological control of Southern blight disease is a potent alternative to chemical fungicides. Although rhizobacteria are prolific candidates, comprehensive reports regarding their use in tomato disease management are limited. The present study screened six rhizobacterial strains for antagonism against S. rolfsii in dual culture and culture filtrate assays. The selected promising strains were tested further for plant-growth-promoting and biocontrol potentials under in vitro, greenhouse, and field conditions. Of the six strains screened, Stenotrophomonas maltophilia PPB3 and Bacillus subtilis PPB9 showed the superior performance displaying the highest antagonism against S. rolfsii in dual culture (PPB3 88% and PPB9 71% inhibition), and culture filtrate assays (PPB3 53-100% and PPB9 54-100% inhibition at various concentrations). Oxalic acid produced by S. rolfsii was significantly inhibited by both rhizobacteria and supported their growth as a carbon source. The strains produced hydrogen cyanide, chitinases, siderophores, biofilm, and indole acetic acid. They showed the potential to solubilize phosphate and fix nitrogen. Seed treatment with S. maltophilia PPB3 and B. subtilis PPB9 improved seed germination and tomato seedling vigour. Significant increases in plant growth, chlorophyll contents, and N, P, and K concentrations were attained in bacterized plants compared to non-treated controls. The application of antagonists on container-grown seedlings in a greenhouse environment and field-grown tomato plants reduced symptoms of damping-off and Southern blight. The sclerotial counts decreased significantly in these soils. Bacteria-inoculated plants had a higher yield than those in the non-treated control. Bacteria colonized the entire roots, and their populations increased significantly in the protected plants. The results show the potential capabilities of S. maltophilia PPB3 and B. subtilis PPB9 for growth promotion, nutrient acquisition, and biocontrol of southern blight disease in tomatoes.

Role of neurotoxicants in the pathogenesis of Alzheimer's disease: a mechanistic insight.

Alzheimer's disease (AD) is the most conspicuous chronic neurodegenerative syndrome, which has become a significant challenge for the global healthcare system. Multiple studies have corroborated a clear association of neurotoxicants with AD pathogenicity, such as Amyloid beta (Aß) proteins and neurofibrillary tangles (NFTs), signalling pathway modifications, cellular stress, cognitive dysfunctions, neuronal apoptosis, neuroinflammation, epigenetic modification, and so on. This review, therefore, aimed to address several essential mechanisms and signalling cascades, including Wnt (wingless and int.) signalling pathway, autophagy, mammalian target of rapamycin (mTOR), protein kinase C (PKC) signalling cascades, cellular redox status, energy metabolism, glutamatergic neurotransmissions, immune cell stimulations (e.g. microglia, astrocytes) as well as an amyloid precursor protein (APP), presenilin-1 (PSEN1), presenilin-2 (PSEN2) and other AD-related gene expressions that have been pretentious and modulated by the various neurotoxicants. This review concluded that neurotoxicants play a momentous role in developing AD through modulating various signalling cascades. Nevertheless, comprehension of this risk agent-induced neurotoxicity is far too little. More in-depth epidemiological and systematic investigations are needed to understand the potential mechanisms better to address these neurotoxicants and improve approaches to their risk exposure that aid in AD pathogenesis.Key messagesInevitable cascade mechanisms of how Alzheimer's Disease-related (AD-related) gene expressions are modulated by neurotoxicants have been discussed.Involvement of the neurotoxicants-induced pathways caused an extended risk of AD is explicited.Integration of cell culture, animals and population-based analysis on the clinical severity of AD is addressed.

Methods for the Characterization of Plant-Growth Promoting Rhizobacteria.

A detailed description of methods most frequently used for the identification and characterization of beneficial microbial strains is presented in this chapter. The methods include microbiological, biochemical, and molecular approaches. Microbiological and biochemical methods comprise a broad range of techniques that are based on the analysis of phosphate solubilization, nitrogenase activity, indole-3-acetic acid production, bacterial motility, presence of catalase and nitrate reductase enzyme, Gram's staining of the cell wall, siderophore production, and microbial chemotaxis. The molecular methods involve a range of techniques that are based on the extraction and analysis of microbial DNA. The extracted nucleic acid can be specifically amplified using polymerase chain reaction (PCR), and subsequently cloned and sequenced. The sequencing of conserved genes such as internal transcribed spacer (ITS) region or 16S rRNA in a microbial genome is used extensively in resolving taxonomic identity of microbial strains. These methods are highly sensitive and allow for a high degree of specificity.

Genetic variation for induced and basal resistance against leaf pathogen Pseudomonas syringae pv. tomato DC3000 among Arabidopsis thaliana accessions.

In Arabidopsis thaliana, significant efforts to determine the effect of naturally occurring variation between phenotypically divergent accessions on different biotic or abiotic stresses are underway. Although it is usually assumed that induced systemic resistance (ISR) against pathogen will covary with plant genetic variation, this assumption has not been tested rigorously in previous experiments. Here, we investigated heritable variation in resistance as well as Penicillium simplicissimum GP17-2-mediated ISR to the bacteria Pseudomonas syringae pv. tomato DC3000 (Pst) among a worldwide collection of accessions of A. thaliana. In this study, 75 Arabidopsis accessions were screened against the bacteria Pst following induction and non-induction treatment and their resistance levels were determined by measuring three components of A. thaliana resistance (infected leaf number, disease severity and pathogen growth). We observed extensive quantitative variation in the number of infected leaves, severity of disease symptoms and the bacterial population size among 75 accessions of A. thaliana infected with Pst. On the contrary, about a two-third of the accessions (49 accessions) showed a reduction in infected leaf number, disease severity and pathogen proliferation after treatment with GP17-2, indicating that GP17-2 induction of resistance is ecotype specific in Arabidopsis. The level of suppression was more pronounced for percent disease severity and pathogen proliferation than for number of infected leaves in ISR-inducible accessions. Accessions non-responsive to GP17-2 treatment generally appeared to be associated with higher basal resistance to infection by Pst. Future study with these parental lines employing a variety of crossing schemes may facilitate identification of major trait loci responsible for GP17-2-mediated ISR in Arabidopsis.

Integrated effect of microbial antagonist, organic amendment and fungicide in controlling seedling mortality (Rhizoctonia solani) and improving yield in pea (Pisum sativum L.).

The study evaluated the comparative performance of a few microbial antagonists, organic amendments and fungicides and their integration for the management of seedling mortality (Rhizoctonia solani Kühn) and yield improvement in pea (Pisum sativum L.). Before setting the experiment in field microplots, a series of in vitro and in vivo experiments were conducted to select a virulent isolate of R. solani, an effective antagonistic isolate of Trichoderma harzianum, a fungitoxic organic amendment and an appropriate fungicide. A greenhouse pathogenicity test compared differences in seedling mortality in pea inoculated by four isolates of R. solani and identified the isolate RS10 as the most virulent one. Among the 20 isolates screened in dual culture assay on PDA, T. harzianum isolate T-3 was found to show the highest (77.22%) inhibition of the radial growth of R. solani. A complete inhibition (100.00%) of colony growth of R. solani was observed when fungicide Bavistin 50 WP and Provax-200 at the rate of 100 and 250 ppm, respectively, were used, while Provax-200 was found to be highly compatible with T. harzianum. Mustard oilcake gave maximum inhibition (60.28%) of the radial growth of R. solani at all ratios, followed by sesame oilcake and tea waste. Integration of soil treatment with T. harzianum isolate T-3 and mustard oilcake and seed treatment with Provax-200 appeared to be significantly superior in reducing seedling mortality and improving seed yield in pea in comparison to any single or dual application of them in the experimental field. The research results will help growers develop integrated disease management strategies for the control of Rhizoctonia disease in pea. The research results show the need for an integrating selective microbial antagonist, organic amendment and fungicide to achieve appropriate management of seedling mortality (R. solani) and increase of seed yield in pea.

Plant growth-promoting fungus Penicillium spp. GP15-1 enhances growth and confers protection against damping-off and anthracnose in the cucumber.

Plant growth-promoting fungi (PGPF) have the potential to confer several benefits to plants in terms of growth and protection against pests and pathogens. In the present study, we tested whether a PGPF isolate, Penicillium spp. GP15-1 (derived from zoysiagrass rhizospheres), stimulates growth and disease resistance in the cucumber plant. The use of the barley grain inoculum GP15-1 significantly enhanced root and shoot growth and biomass of cucumber plants. A root colonization study revealed that GP15-1 was a very rapid and efficient root colonizer and was isolated in significantly higher frequencies from the upper root parts than from the middle and lower root parts during the first 14 d of seedling growth. Inoculating the cucumber seedlings with GP15-1 significantly reduced the damping-off disease caused by Rhizoctonia solani, and the disease suppression effects of GP15-1 were considerably influenced by the inoculum potential of both GP15-1 and the pathogen. Treatment with the barley grain inoculum or a cell-free filtrate of GP15-1 increased systemic resistance against leaf infection by the anthracnose pathogen Colletotrichum orbiculare, resulting in a significant decrease in lesion number and size. Molecular and phylogenetic analyses of internal transcribed spacer sequences of the genomic DNA of GP15-1 revealed that the fungal isolate is a strain of either Penicillium neoechinulatum or Penicillium viridicatum.

The plant growth-promoting fungus Penicillium simplicissimum GP17-2 induces resistance in Arabidopsis thaliana by activation of multiple defense signals.

Arabidopsis thaliana grown in soil amended with barley grain inocula of Penicillium simplicissimum GP17-2 or receiving root treatment with its culture filtrate (CF) exhibited clear resistance to Pseudomonas syringae pv. tomato DC3000 (Pst). To assess the contribution of different defense pathways, Arabidopsis genotypes implicated in salicylic acid (SA) signaling expressing the NahG transgene or carrying disruption in NPR1 (npr1), jasmonic acid (JA) signaling (jar1) and ethylene (ET) signaling (ein2) were tested. All genotypes screened were protected by GP17-2 or its CF. However, the level of protection was significantly lower in NahG and npr1 plants than it was in similarly treated wild-type plants, indicating that the SA signaling pathway makes a minor contribution to the GP17-2-mediated resistance and is insufficient for a full response. Examination of local and systemic gene expression revealed that GP17-2 and its CF modulate the expression of genes involved in both the SA and JA/ET signaling pathways. Subsequent challenge of GP17-2-colonized plants with Pst was accompanied by direct activation of SA-inducible PR-2 and PR-5 genes as well as potentiated expression of the JA-inducible Vsp gene. In contrast, CF-treated plants infected with Pst exhibited elevated expression of most defense-related genes (PR-1, PR-2, PR-5, PDF1.2 and Hel) studied. Moreover, an initial elevation of SA responses was followed by late induction of JA responses during Pst infection of induced systemic resistance (ISR)-expressing plants. In conclusion, we hypothesize the involvement of multiple defense mechanisms leading to an ISR of Arabidopsis by GP17-2.