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An assessment of roles of rhizospheric microbial diversity in plant growth is helpful in understanding plant-microbe interactions. Using random combinations of rhizospheric bacterial species at different richness levels, we analysed the contribution of species richness, compositions, interactions and identity on soil microbial respiration and plant biomass. We showed that bacterial inoculation in plant rhizosphere enhanced microbial respiration and plant biomass with complementary relationships among bacterial species. Plant growth was found to increase linearly with inoculation of rhizospheric bacterial communities with increasing levels of species or plant growth promoting trait diversity. However, inoculation of diverse bacterial communities having single plant growth promoting trait, i.e., nitrogen fixation could not enhance plant growth over inoculation of single bacteria. Our results indicate that bacterial diversity in rhizosphere affect ecosystem functioning through complementary relationship among plant growth promoting traits and may play significant roles in delivering microbial services to plants.

Background The MYB family is one of the most significant groups of transcription factors in plants. However, several MYBs have been linked to secondary metabolism and are important for determining the color of fruit's peel and pulp. Despite being a substantial fruit crop in tropical and subtropical areas of the world, wilt-resistant hybrid guava (Psidium guajava x Psidium molle; PGPM) has not yet been the subject of a thorough examination. This study's goal was to assess the expression of MYB in guava fruit pulp, roots, and seeds to predict its function by in silico analysis of the guava root transcriptome data. Results In the current study, we have mined the MYBs family of MYB genes from the transcriptome of the PGPM guava root. We have mined 15 distinct MYB transcription factor genes/transcripts viz MYB3, MYB4, MYB23, MYB86, MYB90, MYB308, MYB5, MYB82, MYB114, MYB6, MYB305, MYB44, MYB51, MYB46, and MYB330. From the analyses, it was found that R2-MYB and R3-MYB domains are conserved in all known guava MYB proteins. The expression of six different MYB TFs was examined using semi-quantitative RT-PCR in \"Shweta\" pulp (white colour pulp), \"Lalit\" pulp (red color pulp), \"Lalit\" root, and \"Lalit\" seed. Conclusion There were 15 MYB family members observed in guava. They were unequally distributed across the chromosomes, most likely as a result of gene duplication. Additionally, the expression patterns of the particular MYBs showed that MYB may be involved in the control of wilt, fruit ripening, seed development, and root development. Our results allow for a more thorough functional characterization of the guava MYB family genes and open the door to additional research into one essential MYB transcription factor family of genes and its involvement in the growth and ripening of guava fruit.

Root rot and wilt, caused by a complex involving Fusarium chlamydosporum (Frag. and Cif.) and Ralstonia solanacearum (Smith), are serious diseases affecting the cultivation of Coleus forskohlii, a crop with economic potential as a source of the medicinal compound forskolin. The present 2-year field experiments were conducted with two bioinoculants (a native Pseudomonas monteilii strain and the exotic arbuscular mycorrhizal (AM) fungus Glomus fasciculatum) alone and in combination under organic field conditions in order to evaluate their potential in controlling root rot and wilt. Combined inoculation of P. monteilii with G. fasciculatum significantly increased plant height, plant spread, and number of branches; reduced disease incidence; and increased tuber dry mass of C. forskohlii, compared to vermicompost controls not receiving any bioinoculants. Increase in tuber yields was accompanied by an increase in plant N, P, and K uptake. Co-inoculation of P. monteilii with G. fasciculatum significantly improved the percent AM root colonization and spore numbers retrieved from soil. This suggests P. monteilii to be a mycorrhiza helper bacterium which could be useful in organic agriculture. The forskolin content of tubers was significantly increased by the inoculation treatments of P. monteilii, G. fasciculatum, and P. monteilii + G. fasciculatum.

Papaya leaves are used frequently for curing scores of ailments. The medicinal properties of papaya leaves are due to presence of certain bioactive/pharmacological compounds. However, the papaya leaf curl virus (PaLCuV), a geminivirus, is a major threat to papaya cultivation globally. During the present investigation, we observed that PaLCuV infection significantly altered the anatomy, physiology, and bioactive properties of papaya leaves. As compared to healthy leaves, the PaLCuV-infected leaves were found to have reduced stomatal density (76.83%), stomatal conductance (78.34%), photosynthesis rate (74.87%), water use efficiency (82.51%), chlorophyll (72.88%), carotenoid (46.63%), osmolality (48.55%), and soluble sugars (70.37%). We also found lower enzymatic activity (superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT)—56.88%, 85.27%, and 74.49%, respectively). It was found that the size of guard cells (50%), transpiration rate (45.05%), intercellular CO2 concentration (47.81%), anthocyanin (27.47%), proline content (74.17%), malondialdehyde (MDA) (106.65%), and electrolyte leakage (75.38%) was elevated in PaLCuV-infected leaves. The chlorophyll fluorescence analysis showed that the infected plant leaves had a significantly lower value of maximal quantum yield of photosystem II (PSII (Fv/Fm), photochemical quantum yield of photosystem I (PSI (Y(I)), and effective quantum yield of PSII (Y(II)). However, in non-photochemical quenching mechanisms, the proportion of energy dissipated in heat form (Y(NPQ)) was found to be significantly higher. We also tested the bioactivity of infected and healthy papaya leaf extracts on a Caenorhabditis elegans (C. elegans) model system. It was found that the crude extract of papaya leaves significantly enhanced the life span of C. elegans (29.7%) in comparison to virus-infected leaves (18.4%) on application of 100 µg/mL dose of the crude extract. Our research indicates that the PaLCuV-infected leaves not only had anatomical and physiological losses, but that pharmacological potential was also significantly decreased.

Mango (Mangifera indica L.), being a climacteric fruit, is highly perishable due to rapid ripening and post-harvest diseases like anthracnose, which significantly shorten its shelf life and limit long-distance sea export. To mitigate these constraints, a chemical-free secondary metabolite-based formulation (SMsF) was developed to delay ripening and control post-harvest anthracnose during storage. The SMsF possesses dual-action properties and is derived from the culture filtrate of Priestia aryabhattai, exhibiting ACC deaminase activity that restricts ethylene formation. It is also rich in antifungal compounds such as vanillic acid, hydroxybenzoic acid, cryptochlorogenic acid, palmitic acid, and BBIT, which inhibit anthracnose development. Additionally, it contains antioxidants including quercetin, coumaryl quinic acid, oleic acid, and acetylglycitin that enhance shelf life and disease resistance. The efficacy of SMsF was evaluated in mango cv. Banganapalli was stored at 12 ± 1 °C and 85–90% relative humidity under simulated reefer conditions (SRC). Integration of gamma irradiation with SMsF provided superior results in disease control and shelf-life extension. The combined treatment maintained higher fruit firmness (0.86 kg cm−2), optimal total soluble solids (14.3 °B), desirable acidity (0.22%), and complete suppression of anthracnose (PDI = 0) up to 40 days of storage under SRC compared with the control. The findings conclusively demonstrate that the synergistic application of SMsF and gamma irradiation effectively regulates ripening, enhances fruit quality, and ensures complete disease suppression, thereby significantly extending storage life. This approach holds strong scientific and commercial significance as a sustainable, residue-free, and export-oriented technology capable of improving long-distance transportation, reducing post-harvest losses, and promoting safe mango trade.

An integrated approach involving vermicompost, chromate reducing bacteria and AMF was tested to manage the toxic impacts of Cr(VI) on Ocimum basilicum as a model plant. Pot experiments were conducted on O. basilicum plants in an artificially Cr(VI)-contaminated soil in two phases of experiment as bioinoculants experiment and vermicompost experiment. In the first phase of the bioinoculants experiment the series of gradient concentrations of Cr(VI) (0, 25, 50 and 100 mg kg–1 in soil) were evaluated with previously isolated four efficient Cr(VI)-reducing rhizo-bacterial strains (Bacillus Cereus strain SUCR 44, BC; Microbacterium sp. strain SUCR 140, MB; Bacillus thuringiensis strain SUCR186, BT; and Bacillus subtilis strain SUCR188; BS) along with Arbuscular Mycorrhizal Fungus—Glomus fasciculatum (GF) in alone and in co-inoculation form. In the second experiment (vermicompost) the best performing strain (MB) was tested alone or in combination with GF along with different doses of vermicompost. It was observed that vermicompost by itself could be useful in decreasing the bioavailable Cr(VI), uptake of Cr besides improving the nutritional status of plants. The vermicompost also played an important and indirect role and improved herb yield by supporting the multiplication of MB (Microbacterium sp.), an efficient chromate reducing rhizobacteria, that further decreased the bioavailable and toxic form of Cr and improved population and colonization of GF too. The translocation of Cr(VI) was averted through improved colonization of GF, also prevented higher accumulation of Cr in aerial parts (leafy herb) of O. basilicum.

Anthropogenic disturbances are detrimental to the functioning and stability of natural ecosystems. Critical ecosystem processes driven by microbial communities are subjected to these disturbances. Here, we examine the stabilizing role of bacterial diversity on community biomass in the presence of abiotic perturbations such as addition of heavy metals, NaCl and warming. Bacterial communities with a diversity gradient of 1–12 species were subjected to the different treatments, and community biomass (OD 600 ) was measured after 24 h. We found that initial species richness and phylogenetic structure impact the biomass of communities. Under abiotic perturbations, the presence of tolerant species in community largely contributed in community biomass production. Bacterial diversity stabilized the biomass across the treatments, and differential response of bacterial species to different perturbations was the key reason behind these effects. The results suggest that biodiversity is crucial for maintaining the stability of ecosystem functioning and acts as ecological insurance under abiotic perturbations. Biodiversity in natural ecosystems may also uphold the ecosystem functioning under anthropogenic disturbance.

Fruit and vegetable wastes create unhygienic conditions and pose a environmental pollution. The utilization of such wastes as carbon sources for production of enzyme with microbial intervention could be an ecofriendly and profitable approach, apart from diminishing the waste load. The present investigation focused on the feasibility of using mosambi (Citrus limetta) peel as substrate for multienzyme production (pectinase, cellulase and amylase) through microbial intervention. Fifteen fungi were isolated from organic waste and screened in vitro their potential of biodegradation of mosambi peel through enzymes production. The best performing isolate was selected and identified as Trichoderma asperellum NG-125 (accession number-MW287256). Conditions viz. temperature, pH, incubation time and nutrient addition were optimized for efficient enzymes production. The maximum enzyme activity (U ml−1 min−1) of pectinase (595.7 ± 2.47), cellulase (497.3 ± 2.06) and amylase (440.9 ± 1.44) were observed at pH 5.5, incubation temperature of 30 °C after 10 days of fermentation. Moreover, macro-nutrients such as ammonium sulfate (0.1%) and potassium-di-hydrogen-ortho-phosphate (0.01%) further also enhanced the production of enzymes. The SDS-PAGE analysis of purified pectinase, cellulase and amylase using showed molecular mass of 43, 66 and 33 kDa, respectively. The enzyme retention activity (ERA) of aforesaid enzymes was also tested with four different natural fiber matrices viz., bagasse, rice husk, paddy straw and wheat straw. Among these, the maximum ERA was observed on bagasse matrix (pectinase—56.35%, cellulose—77.68% and amylase 59.54%). Enzymatic juice clarification yield obtained with test enzyme was 75.8%, as compared to 80.5% of commercial enzyme. The result indicates that T. asperellum may be exploited as multifaceted biocatalysis.

The purpose of the current study was to evaluate the functional activity and storage viability (at 4 °C and 35 °C) of an immobilized as well as lyophilized multienzyme, viz., pectinase, cellulase, and amylase (PCA) that was produced by Bacillus subtilis NG105 under solid state fermentation (SSF) at 35 ℃ for 10 days using mosambi peel as a substrate. After SSF, the culture media was divided into two aliquots. From the first aliquot, the produced ME was extracted, precipitated, and further immobilized on calcium alginate beads (MEICA). In order to immobilize on mosambi peel matrix, the second aliquot was mixed with acetone and subsequently lyophilized (MELMP). Thus, ready MEICA and MELMP extracted 87.5 and 91.5% juice from mango pulp, respectively. In the reusability study, after 5 cycles, MEICA exhibited 23.8%, 24.4%, and 36.5% PCA activity, respectively. The PCA activity of MEICA and MELMP was examined after 60 days of storage at 4 ℃. The result revealed that the PCA for MEICA declined from 100 to 66%, 58.2%, and 64.5%, respectively, while for MELMP, it dropped from 100 to 84.2%, 82.1%, and 69.7%, respectively. Further, after 60 days of storage, the reduction of total protein content (TPC) in free multienzyme (FME), MEICA, and MELMP was 92.2%, 91.5%, and 36.3% observed, respectively. In the localization study, the maximum levels of multienzyme activity were found in cell exudates. This study demonstrated that immobilizing of multienzyme through lyophilization on waste substrates like mosambi peel boosted its stability and shelf-life along with greatly reducing the cost of products.

Endophytes are regarded with immense potentials in terms of plant growth promoting (PGP) elicitors and mimicking secondary metabolites of medicinal importance. Here in the present study, we explored Bacopa monnieri plants to isolate, identify fungal endophytes with PGP elicitation potentials, and investigate secretion of secondary metabolites such as bacoside and withanolide content under in vitro conditions. Three fungal endophytes isolated (out of 40 saponin producing isolates) from leaves of B. monnieri were examined for in vitro biosynthesis of bacosides. On morphological, biochemical, and molecular identification (ITS gene sequencing), the isolated strains SUBL33, SUBL51, and SUBL206 were identified as Nigrospora oryzae (MH071153), Alternaria alternata (MH071155), and Aspergillus terreus (MH071154) respectively. Among these strains, SUBL33 produced highest quantity of Bacoside A 3 (4093 μg mL −1 ), Jujubogenin isomer of Bacopasaponin C (65,339 μg mL −1 ), and Bacopasaponin C (1325 μg mL −1 ) while Bacopaside II (13,030 μg mL −1 ) was produced by SUBL51 maximally. Moreover, these aforementioned strains also produced detectable concentration of withanolides—Withaferrin A, Withanolide A (480 μg mL −1 ), and Withanolide B (1024 μg mL −1 ) respectively. However, Withanolide A was not detected in the secondary metabolites of strain SUBL51. To best of our knowledge, the present study is first reports of Nigrospora oryzae as an endophyte in B. monnieri with potentials of biosynthesis of economically important phytomolecules under in vitro conditions.