## 3 Discussion
Specifically, _JAZ_ family genes were constitutively and differentially expressed in different tissues of various plants such as wheat [37], rubber tree [39], and _L. aureus_[70]. Furthermore, the widespread expression of _JAZ_ genes in different plant tissues is involved in regulating plant growth and development [1; 41]. Here, we found that seven _McJAZ_ genes were constitutively expressed in the tested tissues, and showed a variable expression profile (Figure 4). These results suggest that different _McJAZ_ genes may play an important role in regulating the growth and development of different tissues in _M. canadensis_. It is intriguing that seven _McJAZ_ genes showed the highest expression in flowers over all other tissuesstudied (Figure 4). Among these, the transcripts of _McJAZ5/6/7_ reached 33-fold, 180-fold and 70-fold within flowers relative to root tissue. Moreover, earlier reports showed that _JAZ_ genes played roles in flower and stamen development in _Arabidopsis_ and in rice [1; 19]. Thus, _McJAZ_ genes may share similar functions with the above-mentioned _JAZ_ genes in flower development. In addition, we found that _McJAZ12/4/5/6_ showed similar expression patterns (Figure 4B), which, taken with the conservation of TIFY and Jas domains among them, suggests some functional redundancy in the _McJAZ12/4/5/6_ in _M. canadensis_. The defense-related hormones JA and ABA induce fluctuation in transcript abundance of _JAZ_ genes in various plants, and this critical transcriptional regulation of _JAZ_ genes is connected with the potential roles of JAZ including JA- and ABA-mediated plant development, defense, and specialized metabolism [19; 29; 37; 38; 45; 47]. For instance, JA treatment and other environmental elicitors rapidly induce _JAZ_ gene expression, which in turn attenuates response to JA [20]. In addition, _OsJAZ1_ was induced by ABA and involved in negative regulation of drought tolerance in rice [47]. Here, the seven studied _McJAZ_ genes were significantly upregulated after MeJA treatment compared with control, further pointing to their probable involvement in JA signaling. Of them, _McJAZ1_, _McJAZ3_, _McJAZ6_, and _McJAZ7_ showed a short-term response to MeJA treatment at the major time points of 1 and 3 h, whereas _McJAZ2_, _McJAZ4_, and _McJAZ5_ showed a continuous response to MeJA treatment from 1 to 24 h (Figure 5A), suggesting that the transcription of _McJAZ_ genes may fall into distinct regulatory pathways. For ABA treatment, only _McJAZ4_ expression was not affected by ABA treatment, the relative expression levels of _McJAZ1_, _McJAZ3_, and _McJAZ7_ were slightly depressed, and _McJAZ2_, _McJAZ5_, and _McJAZ6_ genes were up-regulated in a time-point dependent manner (Figure 5B). Notably, cross-talk between JA and ABA has been reported in plants [29]. Our study shows that _McJAZ2_, _McJAZ5_, and _McJAZ6_ are also co-induced by MeJA and ABA, indicating that these _McJAZ_ genes may regulate cross-talk between these two phytohormones. In addition, studies show that the _JAZ_ family genes exhibited varied expression in response to one or more abiotic stressors in different plants. _JAZ_ family genes are differentially induced by drought, salt, and low temperature in wheat, rice, _Camellia sinensis_, and _Brassica rapa_, and upregulation of these genes is involved in salt and drought tolerance [37; 38; 74; 77]. Here, we found that the identified seven _McJAZ_ genes showed differential upregulation to cope with drought stress, and _McJAZ2_, _McJAZ5_, _McJAZ6_, _McJAZ7_ showed an intense response to drought treatment (Figure 6A). Furthermore, _McJAZ2_, _McJAZ5_, _McJAZ6_, _McJAZ7_ were upregulated after salt treatment (Figure 6B), suggesting that _McJAZ_ genes likely played important roles in resistance to one or more abiotic stressors. In addition, abiotic stress-responsive _McJAZ_ genes were simultaneously upregulated by JA and ABA treatments, suggesting that _McJAZ_ genes may respond to different stresses via diverse phytohormone signaling pathways in _M. canadensis_.