## 2 Results
### McJAZ Genes Are Involved in Response to Drought and Salt Stress  
Abiotic stress is known to severely limit plant growth and development, and affect multiple physiological processes, and the species' geographical distribution. To further examine the potential functions of _McJAZ_ genes in response to abiotic stresses, qRT-PCR assays were employed to investigate the expression patterns of _McJAZ_ genes in _M. canadensis_ treated with drought and salt stress. The results showed that, under drought stress treatment, the expression levels of the seven _McJAZ_ genes were significantly up-regulated at the individual time point, and expression levels varied by gene (Figure 6A). Expression of _McJAZ1_, _McJAZ2_, and _McJAZ7_ or _McJAZ3_ reached maximum levels that were 2 to 37 times higher than the control at 12 h or 1 h. In addition, _McJAZ4_ expression was gradually induced by drought and peaked at 12 h, later declining to a level similar to the control (CK 0 h) at 24 h after drought treatment. On the other hand, the transcripts of _McJAZ5_ and _McJAZ6_ were also gradually induced, and reached their highest levels at nearly 8-fold and 39-fold at 24 h under drought treatment compared with control (Figure 6A).  
In addition, seven _McJAZ_ genes had a fluctuating and significantly different transcriptional response to salt treatment (Figure 6B). Among them, _McJAZ1_ and _McJAZ4_ expression were down-regulated by salt treatment at a subset of time points compared with control (CK 0 h) (Figure 6B). _McJAZ3_ expression was generally down-regulated to varying degrees at each time point after salt treatment, and reached the lowest levels at 24 h. Expression analysis of _McJAZ_ genes also showed that _McJAZ2_ and _McJAZ7_ expression were up-regulated at 1-12 h, and reached maximum levels of more than 6-fold or 4-fold compared with control (CK 0 h) at 12 h or 6 h, respectively. In addition, the transcript  
Figure 6: **Expression profiles of _McJAZ_ genes under drought and salt stress treatments.** Quantitative real-time (qRT)-PCR analysis of the expression levels of _McJAZ1_, _McJAZ2_, _McJAZ3_, _McJAZ4_, _McJAZ5_, _McJAZ6_, and _McJAZ7_ in the two-week-old _M. canadensis_ seedlings under drought (**A**) or 150 mM NaCl (**B**) treatments for 0, 1, 3, 6, 12, and 24 h. The relative expression level of each _McJAZ_ gene was normalized to _ß-actin_ gene and compared with CK (0 h) as reference using the \(2^{-\Delta\text{ACT}}\) method. Data are presented as means \(\pm\) SE of three independent replicates from three propagated cuttings. Asterisks indicate significant differences between the expression level of each _McJAZ_ gene in CK (0 h) versus other time points were analyzed by Student’s \(t\)-test (* \(p<0.05\) or * \(p<0.01\)). CK (0 h) represents an independent control under identical conditions.  
levels of _McJAZ5_ and _McJAZ6_ were up-regulated, and peaked at more than 7-fold or 9-fold compared with the control at 3 h, gradually decreased after prolonged salt treatment (6 and 12 h), then returned to levels similar to control (CK 0 h) at 24 h after salt treatment. These results implied that most of the _McJAZ_ genes were sensitive to drought and salt stress treatments, and are likely involved in drought and salt stress related signaling networks in _M. canadensis_.