## 3 Discussion
In plants, JAZ proteins participate in JA signaling pathways by interacting with JA receptor COII or themselves [19; 34]. In our study, some of the McJAZ proteins were found to interact with McCOIIa in a COR-dependent manner (Figure 8). Furthermore, McJAZ proteins showed variable capacities to form homo- or heterodimers via interacting with each other in a COR-independent manner (Figure 9). These results suggest that the functions of _McJAZ_ gene in _M. canadensis_ might be similar to those in _Arabidopsis_. Previous studies have shown that AtJAZ1 can interact with AtCOII or SICOII in the presence of COR [32]. However, the identified McJAZ proteins only interacted with McCOIIa rather than AtCOII in the presence of COR, suggesting that regulation of the interactions of JAZ-COII may differ across species. In addition, the phylogenetic relationship among the _JAZ_ genes reveals the putative function of them as homologous genes often share similar biological roles. In this study, we found that McJAZ1 and McJAZ2 clustered with AtJAZ1/2, or AtJAZ5/6 into the subgroup B2 or B1. McJAZ3, McJAZ4, and McJAZ5 clustered with AtJAZ3/4 or AtJAZ10 into the subgroup A2 or A1. McJAZ6/7 clustered with AtJAZ7/8 into the group D (Figure 3). It was clear that AtJAZ proteins typically interacted with AtMYC2 to regulate diverse physiological functions including plant metabolism and defense [78; 79]. Additionally, AtJAZ3 interacted with AtSPL9 to regulate plant resistance to insect herbivores [80]. AtJ AZ1/4/9 interacted with AtICE1/2 to regulate freezing tolerance in _Arabidopsis_[25]. AtJ AZ1/8/11 interacted with and attenuated the transcriptional functions of MYB21 and MYB24 to regulate stamen development [81]. AtJ AZ1/2/5/6/8/9/10/11 also regulated JA-mediated anthocyanin biosynthesis and trichome development by interacting with the WD-Repeat/bHLH/MYB complexes in _Arabidopsis_[14]. Given the functional specificity, diversity, and redundancy of _AtJAZ_ genes in _Arabidopsis_[82], McJAZ proteins may regulate plant development, defense, and specialized metabolism including EO biosynthesis by interacting with the as-yet unidentified McMYC2 or additional TFs in _M. canadensis_ (Figure 10). Further investigation needs to be conducted to determine the complete regulatory network of McJAZ proteins. Notably, JA treatment promoted biosynthesis of EO in two _Mentha_ plants [58; 67], and EO from _Mentha_ plants could be used to control plant bacterial disease caused by _A. tumefaciens_ in tomato [83], enhance neighboring plants' resistance to insect herbivores [56], and act as a natural insecticide for control of insects including _Tribolium castaneum_, _Lasioderna serricorne_, and _Liposcelis bostrychophila_ adults [84]. This suggests that manipulation of JA signaling in _Mentha_ plants might have dual roles in regulating EO biosynthesis and affecting the anti-insect or anti-pathogen ability of neighboring  
Figure 10: **A proposed working model of how JA signaling module regulates diverse biological processes in response to JA signaling in _M. canadensis_. A simple model showing the putative role of the JA signaling module in controlling diverse biological processes in _M. canadensis_. McCOII, a homolog of the Arabidopsis F-box protein CORONATINE INSENSTITVE 1 (AtCOI1) ([PERSON] et al., 1998), acts as a putative receptor for the active molecule JA-isoleucine (JA-Ile). Introduction of the exogenous elicitor induces the production of JA-Ile, which is perceived by McCOI1 to form the activated McCOII-JA-Ile complex that subsequently interacts with the repressor, JASMONATE ZIM DOMAIN (JAZ) proteins, and represses its transcriptional inhibitory ability by degradation of McJAZ proteins through the SCFCOI1-dependent 26S proteasome pathway ([PERSON] et al., 2007; [PERSON] et al., 2018). Next, degradation of the McJAZ proteins relieves repression of downstream transcription factors (TFs) including unidentified McMYC2 or other McFs, which are involved in regulating plant development, plant defense, and essential oil (EO) biosynthesis in _M. canadensis_.