In a rather simplistic and anthropocentric manner, plant-associated microbes can be classified as„beneficial, detrimental, or unknown‟ based on their effects on plant growth and health.Microbes secrete diverse classes of molecules that directly or indirectly affect plant growth, development, productivity and overall health
One well documented class of secreted molecules includes phytohormones, such as indole-3-acetic acid, cytokinins and gibberellins, and molecules that mimic phytohormones, such as coronatine produced by Pseudomonas syringae and methylated cytokinins released by Rhodococcus fascians
VOCs produced by soil-borne fungi have been shown to enhance plant growth and/or defense againstbiotic stress
Because relatively few studies have considered fungal VOCs as the influential signal regulating changes in plant physiology, several critical questions remain mostly unanswered: a) Which fungal VOCs enhance plant growth or stress resistance?; b) Do same VOC(s) affect both traits?. How do they manage to increase plant growth while potentially diverting resources to enhance defense?; c) How are such VOCs perceived by plants?; d) Which plant signaling pathways and downstream cellular processes are involved?; and e) How does VOC production contribute to fungal biology and ecology in association with plants?