FPX is a Novel Chemical Inducer That Promotes Callus Formation and Shoot Regeneration in Plants [auxin & cytokinin]

Auxin and cytokinin can regulate callus formation from developed plant organs and shoot regeneration from callus. The regulation of dedifferentiation and regeneration of plant cells by auxin and cytokinin stimulation was considered to be caused by the regulation of reprograming of callus cells, but the hypothesis had been argued still in now. Although elucidation of the regulatory mechanisms of callus formation and shoot regeneration has helped advance plant biotechnology research, many plant species are intractable to transformation because of difficulties with callus regulation. In this study, we identified the compound Fipexide (FPX) as a useful regulatory compound through chemical biology-based screening. Compared with the activity of auxin and cytokinin, FPX showed higher efficiency as a chemical inducer in callus formation, shoot regeneration, and Agrobacterium infection. In regards to morphology, the cellular organization of FPX-induced callus differed from that produced under auxin/cytokinin conditions. According to a microarray analysis, the expressions of approximately 971 genes were two-fold up-regulated by FPX treatment for 2 days. Among these genes, 598 genes were also induced by auxin/cytokinin, while 373 genes, including metabolic regulation-related genes, were specifically expressed only under FPX treatment. FPX can promote callus formations in rice, poplar, and several vegetables. FPX should be a useful tool to reveal unknown mechanisms of plant development and to increase the number of transgenic plant species.

9