3  WIRELESS COMMUNICATION: SIGNAL INPUT-TRANSFER-OUTPUT MODEL
Plants normally release volatile and non-volatile chemicals that can be exploited by other plants as a source of signal molecules (infochemicals). Here, we discuss how these plant infochemicals can be induced by microbes, insects, and environmental stimuli. Infochemicals diffuse via air and soil pores to reach neighbor plants. Receiver plants can amplify the released infochemical signals to expand the effective infochemical signaling zone. Infochemicals perceived by the receiver plants can act as kin recognition signals, growth inhibitors (allelopathy), growth stimulators, and defense signals (Karban, Shiojiri, Ishizaki, Wetzel & Evans, 2013, Kong, Zhang, Li, Xia, Yang, Meiners & Wang, 2018a, Kong, Zhang, Li, Xia, Yang, Meiners & Wang, 2018b, Sharifi et al. , 2018, Sharifi & Ryu, 2018b). Infochemicals can directly change the transcriptome and physiology of receiver plants to prime for imminent threats, or they may indirectly change the plant microbiome in neighboring plants through a facilitative or competitive mechanism (Carvalhais, Dennis, Badri, Kidd, Vivanco & Schenk, 2015, Li, Zhao & Kong, 2020a, Mannaa, Han, Jeon, Kim, Kim, Park, Kim & Seo, 2020, Vannier, Bittebiere, Mony & Vandenkoornhuyse, 2020).