Trends and applications in plant volatile sampling and analysis.

Volatile organic compounds (VOCs) released by plants serve as information and defense chemicals in mutualistic and antagonistic interactions and mitigate effects of abiotic stress. Passive and dynamic sampling techniques combined with gas chromatography-mass spectrometry analysis have become routine tools to measure emissions of VOCs and determine their various functions. More recently, knowledge of the roles of plant VOCs in the aboveground environment has led to the exploration of similar functions in the soil and rhizosphere. Moreover, VOC patterns have been recognized as sensitive and time-dependent markers of biotic and abiotic stress. This focused review addresses these developments by presenting recent progress in VOC sampling and analysis. We show advances in the use of small, inexpensive sampling devices and describe methods to monitor plant VOC emissions in the belowground environment. We further address latest trends in real-time measurements of volatilomes in plant phenotyping and most recent developments of small portable devices and VOC sensors for non-invasive VOC fingerprinting of plant disease. These technologies allow for innovative approaches to study plant VOC biology and application in agriculture.

Abaxial leaf surface-mounted multimodal wearable sensor for continuous plant physiology monitoring.

Wearable plant sensors hold tremendous potential for smart agriculture. We report a lower leaf surface-attached multimodal wearable sensor for continuous monitoring of plant physiology by tracking both biochemical and biophysical signals of the plant and its microenvironment. Sensors for detecting volatile organic compounds (VOCs), temperature, and humidity are integrated into a single platform. The abaxial leaf attachment position is selected on the basis of the stomata density to improve the sensor signal strength. This versatile platform enables various stress monitoring applications, ranging from tracking plant water loss to early detection of plant pathogens. A machine learning model was also developed to analyze multichannel sensor data for quantitative detection of tomato spotted wilt virus as early as 4 days after inoculation. The model also evaluates different sensor combinations for early disease detection and predicts that minimally three sensors are required including the VOC sensors.

Synthesis, characterization, and comparative assessment of antimicrobial properties and cytotoxicity of graphene-, silver-, and zinc-based nanomaterials.

Zinc oxide (ZnO) and graphene oxide (GO) nanoparticles, silver/zinc zeolite (Ag/Zn-Ze), and graphene oxide-silver (GO-Ag) nanocomposites were synthesized and characterized with X-ray powder Diffraction, Field Emission Scanning Electron Microscope and Fourier Transform-Infrared Spectroscopy. The antibacterial efficacy of these nanoparticles was evaluated against E. coli. by shake flask method and plate culture method for different concentrations. For 105 cells/mL initial bacterial concentration, minimum inhibitory concentration (MIC) were <160, <320, <320, and >1280 µg/mL, and antibacterial concentration at which 50% cells are inhibited (IC50) were 47, 90, 78, and 250 µg/mL for Ag/Zn-Ze, GO, GO-Ag, and ZnO, respectively. Therefore, the shake flask method showed that for all nanoparticle concentrations, Ag/Zn-Ze, and GO-Ag exhibited greater inhibition efficacy, which was also highly dependent on initial bacterial concentration. However, in case of the plate culture method, similar range of inhibition capacity was found for Ag/Zn-Ze, GO-Ag, and ZnO, whereas GO showed lower potency to inhibit E. coli. In addition, GO-Ag nanocomposite exhibited more efficacy than Ag/Zn-Ze when the antibacterial surface was prepared with those. However, Ag/Zn-Ze showed no toxicity on Vero cells, whereas GO-Ag exhibited severe toxicity at higher concentrations. This study establishes GO-Ag and Ag/Zn-Ze as potent antimicrobial agents; however, their application dosage should carefully be chosen based on cytotoxic effects of GO-Ag in case of any possible physiological interaction.

Plant pest surveillance: from satellites to molecules.

Plant pests and diseases impact both food security and natural ecosystems, and the impact has been accelerated in recent years due to several confounding factors. The globalisation of trade has moved pests out of natural ranges, creating damaging epidemics in new regions. Climate change has extended the range of pests and the pathogens they vector. Resistance to agrochemicals has made pathogens, pests, and weeds more difficult to control. Early detection is critical to achieve effective control, both from a biosecurity as well as an endemic pest perspective. Molecular diagnostics has revolutionised our ability to identify pests and diseases over the past two decades, but more recent technological innovations are enabling us to achieve better pest surveillance. In this review, we will explore the different technologies that are enabling this advancing capability and discuss the drivers that will shape its future deployment.