Bioactivities evaluation of an endophytic bacterial strain Bacillus velezensis JRX-YG39 inhabiting wild grape.

BACKGROUND: Botrytis cinerea can cause serious disease on lots of plant hosts during growth and postharvest storage. Biocontrol is known to be eco-friendly methods to control pathogens. Plant endophytic bacteria are generally considered as beneficial organisms, since they can promote plant growth and enhance plant immune system. Thus, screening biological control agents is very important for sustainable plant protection. RESULTS: Fifty-six endophytic bacteria were obtained from wild grape. Sixteen isolates and their extracts exhibited significant antifungal activity against B. cinerea. Particularly, strain JRX-YG39 with the strongest inhibition ability had a broad-spectrum antifungal activity. Combining 16S rDNA analysis and the phylogenetic results based on gyrA and gyrB genes, JRX-YG39 was assigned as Bacillus velezensis. JRX-YG39 could produce bioactive VOCs and obviously depressed mycelia growth of B. cinerea. It was confirmed that VOCs released by JRX-YG39 could significantly promote growth and induce defense of Arabidopsis thaliana. Thirty-one bioactive secondary metabolites were further identified from JRX-YG39 culture by gas chromatography-mass spectrometry analysis. Dibutyl phthalate, a potential antifungal substance, was the major compound accounting for 78.65%. CONCLUSIONS: B. velezensis JRX-YG39 has wide broad-spectrum antagonistic activity and significant plant promotion activity. Hence, B. velezensis JRX-YG39 will provide a valuable constituent of modern agricultural practice as biofertilizers and biocontrol agents.

Asymmetric optical links using monolithic III-nitride diodes.

Multiple-quantum well (MQW) III-nitride diodes can both emit and detect light. In particular, a III-nitride diode can absorb shorter-wavelength photons generated from another III-nitride diode that shares an identical MQW structure because of the spectral overlap between the emission and detection spectra of the III-nitride diode, which establishes a wireless visible light communication system using two identical III-nitride diodes. Moreover, a wireless light communication system using a modulating retro-reflector (MRR) enables asymmetric optical links, which forms a two-way optical link using a single transmitter and receiver. Here, in association with an MRR, we propose, fabricate, and characterize asymmetric optical links using monolithic III-nitride diodes, where one III-nitride diode functions as a transmitter to emit light, an MRR reflects light with the encoded information, another monolithically integrated III-nitride diode serves as a receiver to absorb the reflected light to convert optical signals into electrical ones, and the encoded information is finally decoded. Advanced monolithic III-nitride asymmetric optical links can be developed toward Internet of Things (IoT) deployment based on such multifunction devices.