Abstract
The use of volatile organic compounds (VOCs) produced by microorganisms for the biological control of plant diseases has attracted much attention in recent years. In this study, the antifungal activity and identity of VOCs produced by Rahnella aquatilis JZ-GX1 isolated from the rhizosphere soil of pine were determined and analyzed. The effect of the VOCs on the mycelial growth of Colletotrichum gloeosporioides, the pathogen of Liriodendron chinense × tulipifera black spot, was determined by a joined-petri dish fumigation method. An in vitro leaf inoculation method was used to determine the fumigation effect of the VOCs on Liriodendron black spot. VOCs with antifungal activity were collected by headspace solid-phase microextraction (SPME), and their components were analyzed by gas chromatography-mass spectrometry (GC-MS). The results showed that the VOCs secreted by JZ-GX1 inhibited the mycelial growth of the tested pathogen. The VOCs destroyed the morphology of the mycelium, significantly increased the permeability of the cell membrane and downregulated the expression of pathogenicity-related genes during mycelial infection, thus inhibiting the expansion of anthracnose disease spots in leaves. In the volatile compound profile, 3-methyl-1-butanol and 2-phenylethyl methyl ether significantly inhibited the mycelial growth and spore germination of C. gloeosporioides. This work provides a new strategy for the research and application of microorganisms and bioactive compounds to control plant anthracnose.
Highlights
Biological control of plant diseases is an important measure to reduce the use of chemical pesticides and improve plant health (Eva et al, 2019)
The determination of the mycelial growth inhibition rate showed that the volatile organic compounds (VOCs) produced by JZ-GX1 had a good inhibitory effect on the colony growth of C. gloeosporioides
To observe the effect of the VOCs produced by JZ-GX1 on the mycelium morphology of C. gloeosporioides, changes in mycelium morphology were observed by Scanning Electron Microscopy (SEM)
Summary
Biological control of plant diseases is an important measure to reduce the use of chemical pesticides and improve plant health (Eva et al, 2019). Studies have shown that biocontrol agents such as Bacillus, Pseudomonas, Burkholderia, and Streptomyces play important roles in plant pathogen inhibition The most well-studied antifungal metabolites are antibiotics, cell walldegrading enzymes and volatile organic compounds (VOCs), and the VOCs produced during microbial metabolism are important biocontrol factors (Tagele et al, 2019). VOCs at low concentrations can be sensed and can be transmitted over long distances, mediating indirect interactions between organisms; VOCs have been used for the biological control of plant diseases (Sharifah et al, 2019). The VOCs produced by Pseudomonas aureofaciens SPS-41 can be used as a biological fumigant to control disease in sweet potato tuber roots (Zhang et al, 2019). The volatiles produced by Enterobacter asburiae Vt-7 inhibited aflatoxin production in peanut during storage (Gong et al, 2019)
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