Tropical life sciences research最新文献

The phytochemical investigations of the ethyl acetate bark extract of Diospyros lanceifolia have led to the isolation of eight compounds, namely lupeol (1), betulin (2), β-sitosterol (3), oleic acid (4), α-amyrin acetate (5), glyceryl trilinoleate (6), β-amyrin (7) and shinanolone (8). The structures of all compounds were established using various spectroscopic techniques such as 1D and 2D-NMR, FT-IR and HRESIMS, which were then compared with reported literature for validation. All compounds isolated from this plant were screened for an in vitro study against Plasmodium falciparum FCR3 followed by an in silico molecular docking study with the PfATP6 protein. The in vitro results revealed that five compounds exhibited strong to good activity (IC₅₀ < 10 μM). In order of potency, these compounds include 5, 3, 6, 1 and 4 with IC₅₀ values of 0.3 ± 0.3 μM, 0.3 ± 0.3 μM, 1.9 ± 2.2 μM, 4.4 ± 7.4 μM and 8.4 ± 4.9 μM, respectively. Compounds 5 and 3 showed the strongest activity compared to the control drugs artemisinin and chloroquine, with the IC₅₀ of 0.7 ± 0.3 μM and 10.3 ± 2.9 μM, respectively. The in silico molecular docking simulations showed that all active compounds from the in vitro study displayed good binding affinity to the PfATP6 protein binding site, with compounds 3, 1 and 5 demonstrating greater binding affinity compared to the other compounds tested, including artemisinin and chloroquine. All compounds exhibited several hydrophobic interaction modes with amino acids of PfATP6 residues. Interestingly, all compounds exhibited hydrogen bonding with ASN1039 residue, except compound 3. The in silico study of these compounds supports the in vitro antiplasmodial activity findings, suggesting that these compounds are potential lead candidates for the development of new antiplasmodial drugs.

Plant growth-promoting bacteria (PGPB) have been reported to promote plant growth and protect against plant diseases effectively. PGPB can control plant diseases through direct and indirect mechanisms. The direct mechanism involves the ability to provide nutrients and phytohormones. In contrast, the indirect mechanism refers to the ability to suppress the activity of pathogens through the production of various compounds and metabolites. The purpose of this study is to evaluate the plant health-promoting potential of Bacillus species. Several genetic determinants in 18 isolates of PGPB were investigated via polymerase chain reaction based on the genes fenD, sfp, bamC, ituA, aiiA, ipdC and nifH. Plant-beneficial traits were confirmed through seedling growth tests and in vitro antagonistic assays in the laboratory, followed by a field experiment that used selected Bacillus isolates to improve plant growth and control twisted disease in shallots. Results revealed that two Bacillus isolates, B-27 and RC76, have potential as PGPB. Isolates B-27 and RC76 were identified as Bacillus velezensis and B. tropicus, respectively, based on gyrB sequence analysis. The application of B. velezensis B-27 by spraying resulted in the lowest intensity of twisted disease in shallots. In addition, combined treatment with B. velezensis B-27 and B. tropicus RC76 increased plant height and leaf number.

In tropical regions, high temperatures and low nitrogen (N) and phosphorus (P) in soil limit plant performance and fruit production. The soil-beneficial microbes, including rhizobacteria, have the potential to overcome the nutrient problems in the soil. Rhizobacteria fix the dinitrogen, solubilise the P and potassium (K), and produce hormones and other metabolites to stimulate plant development and resistance against environmental challenges like inadequate soil fertility, heavy metal concentrations or drought. Bacterial genera that occur for promoting growth is Bacillus sp., Azospirillum sp., Azotobacter sp, Pantoea sp. and Pseudomonas sp. Despite the prominent role of rhizobacteria in agriculture and the economic value of strawberries, the potential use of rhizobacteria as a biofertiliser in strawberry cultivation in tropical areas is rarely discussed and reviewed. The information obtained from publications from 2014-2023 by using the keywords of Plant Growth Promoting Rhizobacteria (PGPR), tropics, biofertiliser, N fixation, P and K solubilisation, P mineralisation, phytohormones and strawberry is organised according to the rhizobacteria, mechanisms by which they boost plant growth, and research location in tropical area. This review focuses on evaluating (i) the mechanism of rhizobacteria to increase plant growth, (ii) the role of rhizobacteria on strawberry growth, yield and quality and (iii) the impact of rhizobacteria on biotic and abiotic stress alleviation.

The weed Chromolaena odorata has negative impacts on invaded ecosystems. Canopy of its aerial parts and allelochemicals released by the weed can suppress the growth and survival of native species. Field assessment of native trees Aegle marmelos and Senegalia catechu evidenced that a declining trend of their seedlings under higher canopy of C. odorata. Experiments carried out in pots revealed the negative effects of the weed's leachate and shade on growth and development of A. marmelos. The leachate increased proline levels in A. marmelos seedlings by ca. 33% in shade and 43% in light. Specific leaf area and secondary roots were decreased significantly under both light and shade conditions by leachate. In the light condition, leachate reduced seedling biomass by ca. 26% and root length by 16%. Shade alone decreased overall seedling growth, including leaf area and biomass with poor root growth and increased specific leaf area. Results showed that A. marmelos is susceptible to shade and C. odorata leachate during its early stage of growth and development. In addition to other factors contributing to the decline of A. marmelos population in nature, the invasion of C. odorata intensifies the challenge. Our study clarifies that the invasion of C. odorata in native habitat has further contributed to the population decline of native species alongside other contributing factors in nature. Hence, there is an urgent necessity to control and manage C. odorata to protect native species. Removal of C. odorata from the invaded site will be beneficial for approaching light for native seedlings as well as preventing the leaching substances into the soil.

Medicinal plants are rich sources of specialised metabolites, crucial for various fields like agriculture, forestry, food processing, biofuels and environmental remediation. Microbes, particularly endophytic and rhizospheric fungi, play a significant role in optimising the production and regulation of these compounds. Several research showed these fungi in various plants, but they have not been thoroughly studied in Phyllanthus niruri, especially to promote growth and elicit lignan compounds like phyllanthin in P. niruri. A total of 131 fungi, consist of 57 rhizospheric fungi and 74 endophytic fungi, were successfully isolated from P. niruri in six different lowland areas in West Java. The potency assay results indicated that 106 fungi could produce indole-3-acetic acid (IAA). Six fungi could synthesise cellulase, and one fungus had the capability to solubilise phosphate. Our results showed that Fusarium sp., Colletotrichum gloeosporioides, Colletotrichum tenuissimum, Colletotrichum fructicola, Pseudallescheria boydii, Aspergillus aculeatus, Myrothecium inundatum, Colletotrichum truncatum can synthesise IAA. Fusarium sp. and Myrothecium inundatum could synthesise cellulase and only Aspergillus aculeatus have activity as phosphate solubilisation. Cocultivation of P. niruri and eight endophytic and rhizospheric fungi showed that Fusarium sp., C. gloeosporioides, P. boydii, A. aculeatus and M. inundatum had the potential traits to increase biomass, phyllanthin levels and phyllanthin yield. In general, these fungi have the potency to be elicitors to enhance phyllanthin in P. niruri.

Metarhizium spp. are entomopathogenic hyphomycete fungi with great potential as biological control agents against insects and as a component within integrated pest management systems. This study evaluated 10 Metarhizium spp. isolates for their effectiveness against house fly larvae and pupae. The isolates with the highest infection rates were tested for compatibility with insecticides. NMMet_SS9/2 and NMMet_CLPK4/1 were the most effective, with infection rates of 86.67% and 60.00% for larvae and pupae, respectively. Both isolates were cultured on Potato Dextrose Agar (PDA) mixed with Cypas^® 250 EC (100 mL and 50 mL per 6.25 L) and Tanidil^®-T (100 g/L and 50 g/L) to assess the impact of insecticides on mycelial growth. After 28 days, the radial growth of NMMet_SS9/2 (81.33 mm) and NMMet_CLPK4/1 (77.67 mm) on PDA with Cypas^® 250 EC (50 mL per 6.25 L) showed no significant differences (p > 0.05) compared to growth on PDA alone. A spore suspension (1 × 10⁸ spores/mL) of NMMet_SS9/2 and NMMet_CLPK4/1 cultured on PDA with Cypas^® 250 EC (50 mL per 6.25 L) was used to control house fly larvae and pupae, resulting in mortality rates of 93.33% (NMMet_SS9/2) and 75.56% (NMMet_CLPK4/1), with infection rates of 77.78% and 71.11%, respectively. No significant differences (p > 0.05) were observed in mortality or infection rates compared to spores cultured on PDA without insecticides. These findings confirm that NMMet_SS9/2 and NMMet_CLPK4/1 are highly effective against house fly larvae and pupae and can proliferate on media containing Cypas^® 250 EC at 50 mL per 6.25 L without compromising their insecticidal properties, making them promising candidates for integrated pest management strategies.

The study investigated bacterial isolation from lead-contaminated soil, revealing the lower bacterial density compared to agricultural soil bacteria, indicating soil degradation. Among the isolated bacteria, three isolates with codes L03, L16 and L19 exhibited high tolerance to lead concentrations up to 1,500 mg/L. Selected isolates demonstrated the ability to produce Indole-3-Acetic Acid (IAA) hormone, with one strain notably producing the highest IAA concentration. Furthermore, three isolates exhibited significant lead bioaccumulation efficiency. Molecular identification revealed Lysinibacillus fusiformis as the highest IAA-producing strain and lead accumulator. Plant growth experiments analysed the bacteria's potency to alleviate the heavy metal stress on Codiaeum variegatum, Dracaena reflexa and Jasminum humile. Additionally, bacterial addition decreased lead absorption only by D. reflexa, potentially through biosorption and bioaccumulation mechanisms. Integrating L. fusiformis into phytoremediation strategies could offer an effective and sustainable approach for remediating Pb-contaminated environments.

The use of Plant Growth-Promoting Rhizobacteria (PGPR) as a biofertiliser was proven to be successful in the optimisation of plant growth and yield. A field experiment was conducted to evaluate the effectiveness of the PGPR on okra growth, physiology, yield and soil physicochemical properties. The okra was planted and fertilised with organic material (goat dung) at 500 g/plant, NPK fertiliser at 100 g/plant (T1) and 70 g/plant for T2, T3, T4 and T5, respectively. The BRIS soil isolated PGPR, namely UA 1 (Paraburkholderia unamae), UA 6 (Bacillus amyloliquefaciens) and UAA 2 (Enterobacter asburiae) propagated in 6% molasses medium were inoculated with the amount of 40 mL for single strain treatment (T2-T4) and 15 mL of each bacterial inoculum for mixed strains treatment (T5). Results showed that inoculation with PGPR in single or mixed strains has significantly decreased the use of 30% NPK fertiliser and promoted okra growth, physiology, yield and soil chemical properties and bacterial count. Mixed strains (T5) have significantly shown the highest performance with increments of 27.85% of leaf number, 28.56% of okra number, 27.90% of yield per plant and 25.83% of plant total dry biomass. The plant net photosynthesis treated with mixed strains also recorded a 5.27% increment with 26.96% of nitrogen content and 22.79% bacteria count in the soil. The findings of this study suggested that the BRIS soil PGPR inoculants may reduce the amount of chemical fertiliser and have a significant potential to be used as biofertiliser in sustainable agriculture to increase plant growth and yield and soil fertility.

Swietenia macrophylla (S. macrophylla), commonly known as "sky fruit", belongs to the Meliaceae family and is predominantly distributed in the neotropical areas of Central America, Southern Asia and the Pacific region. The plant has a rich tradition of being utilised for its anti-diabetic properties and other health benefits. This study focused on the S. macrophylla seeds ethanolic extract (SMEE) to explore its antihyperglycemic effects in Goto-Kakizaki (GK) Type 2 diabetic rats. Bioactive compounds were extracted using maceration, and a reversed-phase high-performance liquid chromatography (RPHPLC) method was validated to separate two limonoids, swietenine and 3,6-O,O diacetyl swietenolide, from the extracts. The 500 mg/kg SMEE dosage significantly reduced fasting blood glucose levels, making it the selected treatment dose. The SMEE group consistently improved glucose regulation during oral glucose tolerance test (OGTT) on the first (9.88 ± 0.69 mmol/L) and eighth (6.12 ± 0.30 mmol/L) days, showing lower initial fasting blood glucose levels. The RP-HPLC method validation confirmed high linearity, ensuring precise quantification within the 1.56 μg/mL to 200 μg/mL range for swietenine and 3,6-O,O diacetyl swietenolide. The content of these compounds in 1 mg of SMEE was determined as 27.5 μg (2.75%) and 14.53 μg (1.45%), respectively. This study provides robust evidence supporting the antihyperglycaemic properties of S. macrophylla seeds. Future studies could evaluate the long-term metabolic effects of S. macrophylla extract on glucose metabolism, oxidative stress and liver function.

In plants, roots play a vital role in crop performance and yield that impact the agricultural productivity. Pluronic F-68 (PF-68) is a type of non-ionic surfactant that is typically utilised as a plant growth additive. There is a lack of studies on the impact of PF-68 on root growth. This work aims to assess the impacts of PF-68 on recalcitrant MR 219 rice root growth. Supplementation of 0.04% PF-68 enhanced the length (18.50%) and number of roots (15.87%) of MR 219 rice. The PF-68-treated MR 219 rice also showed a significant increment in sugar accumulation (1.73 mg/mL) and glutamate synthase activity (0.88 μmol/g protein). Consistent with the root growth enhancement, MR 219 rice supplemented with PF-68 recorded an increase in transcription levels of Indole-3-Acetic Acid 23 (OsIAA23) (1.84-folds) and WUSCHEL-Related Homeobox 11 (OsWOX11) (2.00-folds). Moreover, the PF-68-treated MR 219 rice also exhibited an enhancement of indole acetic acid (IAA) concentrations (27.33 ng/g FW), further suggesting its role in auxin biosynthesis. Taken together, our study revealed that the introduction of PF-68 enhanced the root growth of MR 219 rice through improved sugar accumulation, glutamate synthase activity and auxin biosynthesis.