Elsherbiny A. Elsherbiny ^1,2* Alessandra Di Francesco ³ Joan W. Bennett ⁴

• ¹ Mansoura University, Mansoura, Egypt
• ² Plant Pathology Department, Faculty of Agriculture, Mansoura University, Mansoura 35516, Egypt, Mansoura, Egypt
• ³ University of Udine, Udine, Italy
• ⁴ Department of Plant Biology, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA, New Brunswick, United States

There is growing evidence that microbial volatile organic compounds (VOCs) regulate many plant and fungal developmental processes, mediate signals that lead to mutualistic relationships such as mycorrhizal formation, and -the subject of this research topic -act as effective antimicrobial agents against various plant pathogens.VOCs are low molecular weight, usually lipophilic metabolites that easily evaporate at room temperature. Most VOCs have characteristic odors, so it is not surprising that a great deal of historical volatile research has been conducted by either food and flavor researchers or perfume chemists. Current microbial metabolomic studies predominantly focus on nonvolatile, often water-soluble metabolites, and overlook VOCs. However, in terrestrial environments, water is not constantly present. Many inter-organism interactions are mediated by VOCs that can travel through water and air. Volatile-facilitated intercellular communication processes are common in nature but understudied in the laboratory. The total profile of volatiles emitted by an organism at a specific sampling time can be described as its 'volatilome', and it is common for the same VOC to be produced by dozens, if not hundreds, of species. Approximately 2000 VOCs have been documented from microbial sources of which 300 have been identified from fungi. More than 1700 VOCs have been found from plants. Since the number of known microbial species is thought to be poorly sampled, there is likely a great deal of untapped VOC diversity yet to be discovered. VOCs may be important components of the biocontrol process. This research topic "The Use of Microbial Volatile Compounds for Controlling Plant Pathogens" demonstrates the myriad ways that VOCs can serve as biofumigants and thereby offer promising alternatives to chemical fungicides and bactericides. Furthermore, this research topic speaks to the breadth, depth, and diversity of biological activities mediated by these small gas-phase molecules. https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2024.1420068/full review the abiotic and biotic interactions that regulate the synthesis of 6-pentyl-alpha-pyrone (6-PP), a ketone generated by Trichoderma fungi, and its impact on plant pathogens through both direct and indirect mechanisms such as induced systemic resistance. Finally, the work by Wu et al. https://www.frontiersin.org/journals/plantscience/articles/10.3389/fpls.2024.1400164/full is notable in that it focused on the mechanism of action displayed by 2-heptanol (= heptan-2-ol) in suppressing the growth of Botrytis cinerea, the necrotrophic gray mold fungus that affects grapes, tomatoes, and other high-value plant crops. Because so little is known about the molecular mechanism of VOC action, it is an important finding that 2-heptanol disrupted membrane transport and increased amino acid transport, ultimately yielding nutrient depletion and cell death. In summary, we hope that this research topic will inspire more scientists to recognize that the chemical accomplishments of fungi and streptomycetes do not end with famous pharmaceutically active natural products like penicillin and streptomycin, but extend to small, gas-phase molecules that pathogens can 'breathe in'. The semiotic organic chemical signals that fungi and other microbes use when communicating in the gas phase is a language waiting to be deciphered and then rationally applied for plant pathogen control.