## 5 Conclusions  
In the present study, the effects of SA and MeJA on flavonoid and carotenoid accumulation were investigated in the juice sacs of Satsuma mandarin in vitro. The results suggested that the plant hormones SA and MeJA are important factors regulating flavonoid and carotenoid accumulation in the citrus juice sacs. The SA treatment was effective to enhance the contents of eriocitrin, narirutin, poncirin, and \(\beta\)-cryptoxanthin in the citrus juice sacs. Whereas the carotenoid and flavonoid accumulation was inhibited by the MeJA treatment in the citrus juice sacs in vitro. The gene expression results suggested that the changes in the flavonoid and carotenoid accumulation in the SA and MeJA treatments were highly regulated at the transcriptional level. In addition, a transcriptional factor _CitWRKY70_ was identified in this study by using the microarray analysis. The changes in the expression of _CitWRKY70_ was consistent with those of the key flavonoid and carotenoid biosynthetic genes, indicating that _CitWRKY70_ could be involved in the regulation of flavonoid and carotenoid accumulation in response to SA and MeJA treatments. In this study, the regulation of flavonoid and carotenoid accumulation by SA and MeJA treatments were investigated, and their molecular mechanisms were deeply discussed in citrus fruit. The results present herein contribute to elucidating the roles of SA and MeJA in plants and provide new strategies to modify flavonoid and carotenoid accumulation in citrus fruit. Moreover,as the flavonoid and carotenoid contents were significantly enhanced by the SA treatment in this study, it was indicated that application of SA could be an effective method to improve the nutritional and commotional values of citrus fruit. In the future study, more in-depth researches on the function of _WRKY70_ and effects of different concentrations of MeJA in citrus fruit are expected, which would contribute to further elucidating the regulation mechanisms of flavonoid and carotenoid accumulation in response to SA and MeJA treatments in citrus fruit.  
The following are available online at [[http://www.mdpi.com/2076-3417/10/24/8916/s1](http://www.mdpi.com/2076-3417/10/24/8916/s1)]([http://www.mdpi.com/2076-3417/10/24/8916/s1](http://www.mdpi.com/2076-3417/10/24/8916/s1)). Table S1: Primer sequences and TaqMan MGB Probes used for the TaqMan real-time RT-PCR of the genes related to plant hormones, flavonoid and carotenoid metabolisms., Table S2: Representative salicylic acid responsive genes showing differential expression (>2-fold) between salicylic acid and control treatments (salicylic acid/ control ratio). Table S3: Representative methyl jasmonate responsive genes showing differential expression (>2-fold) between methyl jasmonate and control treatments (methyl jasmonate/control ratio). Figure S1: Chromatograms in the flavonoid and carotenoid in the juice cases of citrus fruit in vitro.  
Conceptualization, G.M. and M.K.; methodology, T.S., H.F., and T.E.; validation, R.Y., G.M., L.Z., and M.K.; formal analysis, R.Y. and G.M.; investigation, R.Y., M.H., and G.M.; resources, M.Y. and K.Y.; data curation, R.Y., G.M., L.Z., and M.K.; writing--original draft preparation, R.Y. and G.M.; writing--review and editing, L.Z. and M.K.; visualization R.Y., G.M., and L.Z.; supervision, M.K.; project administration, G.M. and M.K.; funding acquisition, G.M. and M.K. All authors have read and agreed to the published version of the manuscript.  
This work was supported by KAKENHI grant numbers JP26292015 (to M.K.) and JP19K06030 (to G.M.) from Japan Society for the Promotion of Science (JSPS).  
The authors declare no conflict of interest.