Challenges and applications of volatile organic compounds monitoring technology in plant disease diagnosis

Pollution pressure drives microbial assemblages that improve the phytoremediation potential of heavy metals by Ricinus communis

Due to the rapid expansion of industrial activity, soil pollution has intensified. Plants growing in these polluted areas have developed a rhizobiome uniquely and specially adapted to thrive in such environments. However, it remains uncertain whether pollution acts as a sufficiently selective force to shape the rhizobiome, and whether these adaptations endure over time, potentially aiding in long-term phytoremediation. Therefore, in the present study, we aimed to compare whether the microbiome associated with roots from plants germinated in polluted riverbanks will improve the phytoremediation of Cd and Pb under mesocosm experiments compared with plants germinating in a greenhouse. The experimental design was a factorial 2 × 2, i.e., the origin of the plant and the presence or absence of 100 mg/L of Cd and 1000 mg/L of Pb. Our results showed that plants germinated in polluted riverbanks have the capacity to accumulate twice the amount of Pb and Cd during mesocosm experiments. The metagenomic analysis showed that plants from the river exposed to heavy metals at the end of mesocosm experiments were rich in Rhizobium sp. AC44/96 and Enterobacter sp. EA-1, Enterobacter soli, Pantoea rwandensis, Pantoea endophytica. In addition, those plants were uniquely associated with Rhizobium grahamii, which likely contributed to the differences in the levels of phytoremediation achieved. Furthermore, the functional analysis revealed an augmented functional potential related to hormones, metallothioneins, dismutases, and reductases; meanwhile, the plants germinated in the greenhouse showed an unspecific strategy to exceed heavy metal stress. In conclusion, pollution pressure drives stable microbial assemblages, which could be used in future phytostabilization and phytoremediation experiments.

Portable hydrogel kit based on Michael addition reaction for (E)-2-hexenal gas detection

Plants exhibit rapid responses to biotic and abiotic stresses by releasing a range of volatile organic compounds (VOCs). Monitoring changes in these VOCs holds the potential for the early detection of plant diseases. This study proposes a method for identifying late blight in potatoes based on the detection of (E)-2-hexenal, one of the major VOC markers released during plant infection by Phytophthora infestans. By combining the Michael addition reaction with cysteine-mediated etching of aggregation-induced emission gold nanoclusters (Au NCs), we have developed a portable hydrogel kit for on-site detection of (E)-2-hexenal. The Michael addition reaction between (E)-2-hexenal and cysteine effectively alleviates the etching of cysteine-mediated Au NCs, leading to a distinct fluorescence color change in the Au NCs, enabling a detection limit of 0.61 ppm. Utilizing the superior loading and diffusion characteristics of the three-dimensional structure of agarose hydrogel, our sensor demonstrated exceptional performance in terms of sensitivity, selectivity, reaction time, and ease of use. Moreover, quantitative measurement of (E)-2-hexenal was made easier by using ImageJ software to transform fluorescent images from the hydrogel kit into digital data. Such method was effectively used for the early detection of potato late blight. This study presents a low-cost, portable fluorescent analytical tool, offering a new avenue for on-site detection of plant diseases.

Unveiling the hidden impact: How biodegradable microplastics influence CO2 and CH4 emissions and Volatile Organic Compounds (VOCs) profiles in soil ecosystems

Biodegradable plastics promise eco-friendliness, yet their transformation into microplastics (bio-MPs) raises environmental alarms. However, how those bio-MPs affect the greenhouse gases (GHGs) and volatile organic compounds (VOCs) in soil ecosystems remains largely unexplored. Here, we investigated the effects of diverse bio-MPs (PBAT, PBS, and PLA) on GHGs and VOCs emission in typical paddy or upland soils. We monitored the carbon dioxide (CO2) and methane (CH4) fluxes in-situ using the self-developed portable optical gas sensor and analyzed VOC profiles using a proton-transfer reaction mass spectrometer (PTR-MS). Our study has revealed that, despite their biodegradable nature, bio-MPs do not always promote soil GHG emissions as previously thought. Specifically, PBAT and PLA significantly increased CO2 and CH4 emissions up to 1.9-7.5 and 115.9-178.5 fold, respectively, compared to the control group. While PBS exhibited the opposite trend, causing a decrease of up to 39.9% for CO2 and up to 39.9% for CH4. In addition, different types of bio-MPs triggered distinct soil VOC emission patterns. According to the Mann-Whitney U-test and Partial Least Squares Discriminant Analysis (PLS-DA), a recognizable VOC pattern associated with different bio-MPs was revealed. This study claims the necessity of considering polymer-specific responses when assessing the environmental impact of Bio-MPs, and providing insights into their implications for climate change.

Flexible wearable sensors for crop monitoring: a review

Crops were the main source of human food, which have met the increasingly diversified demand of consumers. Sensors were used to monitor crop phenotypes and environmental information in real time, which will provide a theoretical reference for optimizing crop growth environment, resisting biotic and abiotic stresses, and improve crop yield. Compared with non-contact monitoring methods such as optical imaging and remote sensing, wearable sensing technology had higher time and spatial resolution. However, the existing crop sensors were mainly rigid mechanical structures, which were easy to cause damage to crop organs, and there were still challenges in terms of accuracy and biosafety. Emerging flexible sensors had attracted wide attention in the field of crop phenotype monitoring due to their excellent mechanical properties and biocompatibility. The article introduced the key technologies involved in the preparation of flexible wearable sensors from the aspects of flexible preparation materials and advanced preparation processes. The monitoring function of flexible sensors in crop growth was highlighted, including the monitoring of crop nutrient, physiological, ecological and growth environment information. The monitoring principle, performance together with pros and cons of each sensor were analyzed. Furthermore, the future opportunities and challenges of flexible wearable devices in crop monitoring were discussed in detail from the aspects of new sensing theory, sensing materials, sensing structures, wireless power supply technology and agricultural sensor network, which will provide reference for smart agricultural management system based on crop flexible sensors, and realize efficient management of agricultural production and resources.

Novel Pseudomonas Species Prevent the Growth of the Phytopathogenic Fungus Aspergillus flavus

In response to the escalating demand for sustainable agricultural methodologies, the utilization of microbial volatile organic compounds (VOCs) as antagonists against phytopathogens has emerged as a viable eco-friendly alternative. Microbial volatiles exhibit rapid diffusion rates, facilitating prompt chemical interactions. Moreover, microorganisms possess the capacity to emit volatiles constitutively, as well as in response to biological interactions and environmental stimuli. In addition to volatile compounds, these bacteria demonstrate the ability to produce soluble metabolites with antifungal properties, such as APE Vf, pyoverdin, and fragin. In this study, we identified two Pseudomonas strains (BJa3 and MCal1) capable of inhibiting the in vitro mycelial growth of the phytopathogenic fungus Aspergillus flavus, which serves as the causal agent of diseases in sugarcane and maize. Utilizing GC/MS analysis, we detected 47 distinct VOCs which were produced by these bacterial strains. Notably, certain volatile compounds, including 1-heptoxydecane and tridecan-2-one, emerged as primary candidates for inhibiting fungal growth. These compounds belong to essential chemical classes previously documented for their antifungal activity, while others represent novel molecules. Furthermore, examination via confocal microscopy unveiled significant morphological alterations, particularly in the cell wall, of mycelia exposed to VOCs emitted by both Pseudomonas species. These findings underscore the potential of the identified BJa3 and MCal1 Pseudomonas strains as promising agents for fungal biocontrol in agricultural crops.

Design and Simulation of the Microcantilever Biosensor for MITF Antigen and D5 Monoclonal Antibody Interaction Finite Element Analysis, and Experimental

BACKGROUND

Biosensors and MEMS have witnessed rapid development and enormous interest over the past decades. Constant advancement in diagnostic, medical, and chemical applications has been demonstrated in several platforms and tools. In this study, the analytical and FEA of the microcantilever used in biomolecular analyses were compared with the experimental analysis results.

METHODS

In this study, MITF antigen, which is a melanoma biomarker, and anti-MITF antibody (D5) were selected as biomolecules. A MEMS-type microcantilever biosensor was designed by functionalizing the AFM cantilever by utilizing the specific interaction dynamics and intermolecular binding ability between both molecules. Surface functionalization of cantilever micro biosensors was performed by using FEA. The stress that will occur as a result of the interactions between the MITF-D5 has been determined from the deviation in the resonant frequency of the cantilever.

RESULTS

It has been found that the simulation results are supported by analytical calculations and experimental results.

CONCLUSION

The fact that the results of the simulation study overlap with the experimental and mathematical results allows us to get much cheaper and faster answers compared to expensive and time-consuming experimental approaches.

Acetone Detection and Classification as Biomarker of Diabetes Mellitus Using a Quartz Crystal Microbalance Gas Sensor Array

A gas sensor array was developed and evaluated using four high-frequency quartz crystal microbalance devices (with a 30 MHz resonant frequency in fundamental mode). The QCM devices were coated with ethyl cellulose (EC), polymethylmethacrylate (PMMA), Apiezon L (ApL), and Apiezon T (ApT) sensing films, and deposited by the ultrasonic atomization method. The objective of this research was to propose a non-invasive technique for acetone biomarker detection, which is associated with diabetes mellitus disease. The gas sensor array was exposed to methanol, ethanol, isopropanol, and acetone biomarkers in four different concentrations, corresponding to 1, 5, 10, and 15 µL, at temperature of 22 °C and relative humidity of 20%. These samples were used because human breath contains them and they are used for disease detection. Moreover, the gas sensor responses were analyzed using principal component analysis and discriminant analysis, achieving the classification of the acetone biomarker with a 100% membership percentage when its concentration varies from 327 to 4908 ppm, and its identification from methanol, ethanol, and isopropanol.