Plant roots exude a plethora of chemical compounds into the rhizosphere, the soil environment surrounding the root system. These compounds include ions, free oxygen, water, enzymes, and a diverse array of secondary metabolites that play important roles in microbe attraction to the roots (Bais et al., 2006;Hosseini et al., 2013). In the rhizosphere, plant roots interact with a variety of organisms such as insects, nematodes, and a vast range of microorganisms, such as fungi, bacteria, and protozoans. These interactions can be beneficial, pathogenic, or neutral for the plant (Campos-Soriano et al., 2012;Pineda et al., 2010;Zamioudis & Pieterse, 2012). Regarding the pathogenic interactions between plants and microbes, plant roots secrete antimicrobial compounds to defend themselves (Bais et al., 2006;Bednarek et al., 2005).Terpenes, a class of volatile secondary metabolites, constitute a major portion of root exudates (Bais et al., 2006). They are