The use of synthetic fungicides represents the most common strategy to control plant pathogens. Excessive and/or long-term distribution of chemicals is responsible for increased levels of environmental pollution, as well as adverse health consequence to humans and animals. These issues are deeply influencing public perception, as reflected by the increasing demand for safer and eco-friendly agricultural commodities and their by-products. A steadily increasing number of research efforts is now devoted to explore the use of safer and innovative approaches to control plant pathogens. The use of microorganisms as biological control agents (BCAs) represents one of the most durable and promising strategies. Among the panoply of microbial mechanisms exerted by BCAs, the production of volatile organic compounds (VOCs) represents an intriguing issue, mostly exploitable in circumstances where a direct contact between the pathogen and its antagonist is not practicable. VOCs are potentially produced by all living microorganisms, and may be active in the biocontrol of phytopathogenic oomycetes, fungi, and bacteria by means of antimicrobial activity and/or other cross-talk interactions. Their biological effects, the reduced residuals in the environment and on agricultural commodities, and the ease of application in different agricultural systems make the use of VOCs a promising and sustainable approach to replace synthetic fungicides in the control of plant pathogens. In this review, we focus on VOCs produced by bacteria and fungi and on their role in the cross-talk existing between the plant pathogens and their host. Biologic systemic effect of the microbial volatile blends on both pathogen and host plant cells is also briefly reviewed.

AITC used as a soil fumigant (30-50 g m ) effectively controlled major bacterial and fungal pathogens, root-knot nematode, weeds and increased plant vigor, yield and farmers' income in tomato cultivated under protected agriculture in China. © 2018 Society of Chemical Industry.

As a substitute for methyl bromide, effects of allyl isothiocyanate (AITC) on nontarget microorganisms in soil are poorly understood. This study measured the half-life of AITC in the soil as well as its effects on the soil substrate-induced respiration (SIR) and on communities of soil bacteria and fungi. The results showed that AITC had a short half-life and a short-term inhibition of SIR; high-throughput sequencing analysis showed that AITC had less effect on bacterial than fungal communities. Fumigation reduced the diversity of soil bacteria temporarily, but stimulated the diversity of soil fungi in the long-term and significantly changed the structure of the fungal community. Following AITC fumigation there were significant increases in the relative abundance of probiotics such as Sphingomonas, Streptomyces, Hypocreales, Acremonium, Aspergillus, and Pseudallescheria that help to control plant diseases. Our study provided useful information for assessing the ecological safety of AITC.