## Results
### Autofluorescent Analysis of Camptothecin in Transgenic Hairy Roots  
Camptothecin can be autofluorescence, which provides a direct way to observe the distribution of CPT in hairy roots. Besides, relative concentrations of CPT in different hairy roots can be examined by comparing the size of the fluorescence area and the intensity of fluorescence. The selected root tips were collected from OE-14, S-10, and EV (transformed empty vector) transgenic hairy roots. The area of fluorescence at the root tip was significantly smaller in _OpWRKY3-SRDX_ overexpression hairy roots compared with the control (Figure 4). The root tips of the S-10 line were extremely shortened with a decreasing number of branches in the root-hair zone. However, the fluorescence pattern showed no significant difference between OE-14 and EV hairy root tips. These results indicated that _OpWRKY3_ may be involved in the regulation of hairy root growth and root tip morphogenesis.  
Metabolism of Camptothecin and Intermediate Compound in Hairy Roots Overexpression or Representing OpWRKY3  
Based on the expression level of _OpWRKY3_, the biomass of chosen hairy roots lines was analyzed. The fresh weight (1.278 g) and dry weight (0.042 g) were significantly decreased in _OpWRKY3_ repression transgenic hairy roots, compared to the control (5.5 g, 0.30g) (Figure S3). The fresh weight (6.148 g) of _OpWRKY3_ overexpression transgenic hairy roots was significantly increased whereas dry weight (0.312 g) was not significantly different compared to the control. Among them, dry weight of OE-8, 13, 14 lines was slight increase. The results indicated that repression of _OpWRKY3_ inhibited the growth of hairy roots, and _OpWRKY3_ may be a transcription factor involved in growth and development of hairy roots.  
To study whether _OpWRKY3_ participated in the regulation of camptothecin biosynthesis, the concentration and total production of camptothecin and three intermediate compounds (tryptamine, loganin and secologanin) in _OpWRKY3_ transgenic hairy roots and medium were investigated. Compared with OE lines an opposite accumulation pattern was observed for each compound in S lines. The overexpression of _OpWRKY3_ resulted in increased significantly login concentration in transgenic hairy roots while repression of _OpWRKY3_ decreased the login concentration, compared to control lines (Figure S4B). In contrast, the secologanin concentration was down-regulated significantly by 70% in OE lines, whereas it was up-regulated significantly by 1.7-fold in S lines (Figure S4C). The tryptamine concentration was slight change in OE lines while it was decreased significantly in S lines (Figure S4A). In addition, the overexpression or repression of _OpWRKY3_ showed no significant change in the concentration of camptothecin, compared to the control (Figure S4D).  
The total production (hairy roots and medium) of tryptamine, loginin and CPT were up-regulated significantly by 1.28, 1.59, 1.37-fold in OE lines while the total production of tryptamine, loginin and CPT were down-regulated significantly by 86%, 81%, and 77% in S lines, compared to control lines (Figure 5). Among them, the CPT production was increased significantly in line OE-8, 13, and 14, while CPT production was slightly high in line OE-1 and 4 (Figure 5D). However, the overexpression of _OpWRKY3_ resulted in decreased significantly secologanin production in transgenic hairy roots while repression of _OpWRKY3_ increased significantly the secologanin production (Figure 5C). These results suggested that _OpWRKY3_ may be related to the biosynthesis of tryptamine, loganin, secologanin and camptothecin.