Immunoassay‐based Techniques for Early and Specific Detection of Latent Postharvest Anthracnose in Mango

The postharvest anthracnose pathogen Colletotrichum gloeosporioides inciting latent or quiescent infection of mango was detected in early stages using immunoassay methods. Twenty‐five pathotypes isolated from different agroclimatic zones of Tamil Nadu, Karnataka and Pondicherry, India, revealed the variation in protein profile analysis (SDS‐PAGE). The polyclonal antibodies (PCA) were raised against the unfractioned mycelial protein (UMP) and a 40‐kDa polypeptide present in all pathotypes. Standardization of antigen and antiserum dilutions revealed that an antigen dilution of 1 : 200 (protein concentration of 20 μg/ml) and antiserum dilution of 1 : 100 (protein concentration of 40 μg/ml raised against UMP) and 1 : 200 (protein concentration of 20 μg/ml raised against 40 kDa polypeptide) was found to be optimum for the detection of anthracnose pathogen. Both antisera detected the C. gloeosporioides antigen in enzyme‐linked immunosorbent assays (ELISAs), dot immunobinding assays (DIBAs) and Western blots. The specificity in reaction was compared by isolating other Colletotrichum spp. from various hosts viz., C. lindemuthianum (beans), C. falcatum (sugarcane), C. musae (banana), C. capsici (chillies) and Botryodiplodia theobromae (mango). The antisera generated against UMP revealed the cross‐reaction with other host isolates and mango stem end rot pathogen (B. theobromae). The PCA raised against 40‐kDa polypeptide exhibited the specific reaction with C. gloeosporioides isolates in all the immunoassay techniques. By utilizing both PCA, the presence of latent infection was observed in healthy‐looking leaves, flowers and fruits in orchard conditions. The fruit tissues recorded high absorbance values followed by flowers and leaves in all the detection methods. The ELISA technique was also useful in assessing the pathogen inoculum at various biocontrol formulations sprayed mango trees under field conditions. The fluorescent pseudomonad strains mixture (KFP1 + FP7) amended with chitin sprayed at 30‐day intervals revealed the significant reduction in pathogen load than other formulations and unsprayed control.     

Integrated control of fruit rot and powdery mildew of chilli using the biocontrol agent Pseudomonas fluorescens and a chemical fungicide

A combined strategy of chilli fruit rot and powdery mildew control consisting of reduced fungicide dose and biological control with antagonistic Pseudomonas fluorescens (Pf1) was evaluated. The sensitivity of P. fluorescens to fungicide azoxystrobin at different concentrations (100, 150, 200, 250 and 300 ppm) was tested by turbidometric method. The grown bacterium (Pf1) was tolerant to all concentrations of azoxystrobin. In two field trials, Pf1 tested in combination with reduced concentration of azoxystrobin was highly efficient in management of both diseases of chilli. Biological control of Colletotrichum capsici and Leveillula taurica with P. fluorescens (Pf1) was effective but less so than fungicide alone at the standard dose. However, combination of the biological control agent with a 50% reduction of fungicide dose was as effective as the standard fungicide alone. Application of P. fluorescens along with azoxystrobin significantly increased the survival of Pf1 in the phylloplane of chilli. Further, there were ‘twofold’ increases in activities of peroxidase, polyphenol oxidase, phenylalanine ammonia-lyase, β-1,3-glucanase, chitinase and phenolics in plants treated with Pf1 plus azoxystrobin.     

A new microbial consortia containing entomopathogenic fungus,Beauveria bassiana and plant growth promoting rhizobacteria,Pseudomonas fluorescens for simultaneous management of leafminers and collar rot disease in groundnut

The virulence of 20 isolates of Beauveria bassiana (Balsamo) Vuillemin to larvae of the leafminer, Aproaerema modicella, was tested in the laboratory. Leafminer larvae were sprayed with a standard concentration of 1×10⁸ condia/mL of each B. bassiana isolate. All the B. bassiana isolates tested were pathogenic to A. modicella and the mortality varied between 16.7 and 68.9%. Beauveria bassiana isolate B2 was found to be the most virulent followed by isolate B4 which resulted in 59% mortality. Beauveria isolate B2 was selected for dose–response mortality studies with four different doses (1×10², 1×10⁴, 1×10⁶ and 1×10⁸ conidia/mL). Among the various doses tested, 1×10⁸ conidia/mL produced the highest mortality (70.7%). In addition, morphogenesis of the insect pest in all stages, larval, pupal and adult was greatly affected due to fungal infection. Further, B. bassiana isolate B2 and two Pseudomonas fluorescens strains, TDK1 and Pf1 were tested alone and in combination for suppression of groundnut leafminer and collar rot disease and promotion of plant growth and yield both under glasshouse and field conditions. The mixture of B. bassiana and P. fluorescens strains significantly reduced the leafminer and collar rot disease incidences when applied as talc-based formulation through seed, soil and foliar application under glasshouse and field conditions.     

A new fluorescent chemosensor for cadmium(II) based on a pyrene‐appended piperidone derivative and its β‐cyclodextrin complex

We report, in this article, a piperidin‐4‐one derivative carrying pyrenyl fluorescent reporter groups which acts as a Cd²⁺ ion sensor. The compound is synthesized and characterized using IR and NMR spectral techniques. The compound forms an inclusion complex with β‐cyclodextrin. It selectively binds to Cd²⁺ ions in water and aqueous β‐cyclodextrin media. The stoichiometry of the host–guest complex of the compound with β‐cyclodextrin is 1:2. The ligand–metal ion binding stoichiometry is 1:1 both in water and in β‐cyclodextrin. The linear concentration range of detection of the metal ion is reported. Cyclodextrin complex formation does not affect the metal ion selectivity of the compound.     

Differential responses of sorghum genotypes to drought stress revealed by physio-chemical and transcriptional analysis

Molecular Biology Reports - Sorghum is an essential food crop for millions of people in the semi-arid regions of the world, where its production is severely limited by drought stress. Drought in...     

A simply synthesized biphenyl substituted piperidin‐4‐one for the fluorescence chemosensing of Cd2+

Ion‐induced change in fluorescence is a straight‐forward method for detection of toxic metal ions showing immediate response. Cadmium ions are toxic to the environment. We report in this paper a piperidine‐4‐one‐based fluorescent chemosensor of Cd²⁺ ions, designed and synthesized by a simple method. The compound is characterized using infra‐red (IR) and ¹H–NMR spectral techniques. The chemosensor showed Cd²⁺ ion selectivity and sensitivity in aqueous solution. The stoichiometry and the binding constants were determined using fluorescence spectroscopy. Piperidine‐4‐one shows a 1:1 stoichiometric binding to Cd²⁺. The limit of detection of Cd²⁺ was reported.     

Molecular docking analyses of Avicennia marinaderived phytochemicals against white spot syndrome virus (WSSV) envelope protein-VP28

White spot syndrome (WSS) is one of the most common and most disastrous diseases of shrimp worldwide. It causes up to 100% mortality within 3 to 4 days in commercial shrimp farms, resulting in large economic losses to the shrimp farming industry. VP28 envelope protein of WSSV is reported to play a key role in the systemic infection in shrimps. Considering the most sombre issue of viral disease in cultivated shrimp, the present study was undertaken to substantiate the inhibition potential of Avicennia marinaderived phytochemicals against the WSSV envelope protein VP28. Seven A. marina-derived phytochemicals namely stigmasterol, triterpenoid, betulin, lupeol, avicenol-A, betulinic acid and quercetin were docked against the WSSV protein VP28 by using Argus lab molecular docking software. The chemical structures of the phytochemicals were retrieved from Pubchem database and generated from SMILES notation. Similarly the protein structure of the envelope protein was obtained from protein data bank (PDB-ID: 2ED6). Binding sites were predicted by using ligand explorer software. Among the phytochemicals screened, stigmasterol, lupeol and betulin showed the best binding exhibiting the potential to block VP28 envelope protein of WSSV, which could possibly inhibit the attachment of WSSV to the host species. Further experimental studies will provide a clear understanding on the mode of action of these phytochemicals individually or synergistically against WSSV envelope protein and can be used as an inhibitory drug to reduce white spot related severe complications in crustaceans.     

Quantifying seasonal thrips population dynamics in relation to temperature and wheat senescence

The incidence of thrips in the High Plains of Texas (USA) was investigated using sticky traps during the 2021 and 2022 seasons. Yellow sticky traps were placed in wheat fields and collected and replaced weekly and thrips were counted under a dissecting scope. Weekly wheat reflectance measurements were taken using a hyperspectral radiometer from which normalized difference vegetation index (NDVI) was calculated for each measurement. Temperature (degree day) and NDVI values were then related to weekly thrips incidence using regression. Thrips incidence curvilinearly increased over time during each of the two seasons and reached a maximum in the middle of June, after which it declined sharply. There was a strong positive relationship between degree days and thrips incidence until the incidence reached a maximum, whereas the incidence was negatively related to NDVI values. Analysis of the thrips changes over time progress with the two variables together showed that degree day has greater impact on thrips incidence than NDVI. However, the steep decline in thrips abundance after its peak in mid-June suggests that senesced wheat fields with NDVI values near zero are not significant sources of thrips, signifying the importance of wheat growth stages in the seasonal population dynamics of thrips. Overall, the 2-year results were generally consistent in trends of thrips incidence during the season, which may need to be considered when choosing vegetable planting dates in the region.