FPX is a Novel Chemical Inducer that Promotes Callus Formation and Shoot Regeneration in Plants

Abstract

Auxin and cytokinin control callus formation from developed plant organs as well as shoot regeneration from callus. Dedifferentiation and regeneration of plant cells by auxin and cytokinin stimulation are considered to be caused by the reprogramming of callus cells, but this hypothesis is still argued to this day. Although an 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 formation. In this study, we identified fipexide (FPX) as a useful regulatory compound through a chemical biology-based screening. FPX was shown to act as a chemical inducer in callus formation, shoot regeneration and Agrobacterium infection. With regards to morphology, the cellular organization of FPX-induced calli differed from those produced under auxin/cytokinin conditions. Microarray analysis revealed that the expression of approximately 971 genes was up-regulated 2-fold after a 2 d FPX treatment compared with non-treated plants. Among these 971 genes, 598 genes were also induced by auxin/cytokinin, whereas 373 genes were specifically expressed upon FPX treatment only. FPX can promote callus formations in rice, poplar, soybean, tomato and cucumber, and thus can be considered a useful tool for revealing the mechanisms of plant development and for use in plant transformation technologies.

Optimization of Mature Embryo-Based Tissue Culture and Agrobacterium-Mediated Transformation in Model Grass Brachypodium distachyon

“…The validation of the new chemical inducer will not only benefit the process of transgenic performance but also add new knowledge to the functional analysis of developmental research in the model grass. FPX, as a new chemical inducer, has been employed in callus and shoot formation in mature and immature embryos in Brachypodium [21]. Our results also reinforced the ability of callus and shoot regeneration of FPX in Brachypodium .…”

“…Recently, Nakano et al [21] demonstrated that FPX could function as a chemical inducer that promotes callus formation and shoot regeneration in plants. To examine if FPX can improve callus induction in our system, we conducted a comparative analysis between FPX and the regularly used chemical 2,4-D. Our results revealed that callus were indeed induced on the FPX medium.…”

Effect of nanocarbon molecules on theArabidopsis thalianatranscriptome

“…A transcriptome is often already altered before organisms start to the physiological response to the treatment. Thus, transcriptome analyses of plants treated with small molecules provided insight into action mechanism of the molecules[17-19]. Thus, we conducted a genome-wide gene expression analysis to understand plant responses to nanocarbon molecules.…”

“…Whole organs (cotyledons, hypocotyl, and root) was exposed to the treatment. It was demonstrated that 1-50 μM of bioactive small molecules change gene expression in Arabidopsis seedlings[17,18,20]. Thus we assumed that nanocarbon molecules may affect gene expression if these molecules have any biological activities.…”

Plant Chemical Biology

“…Roots, shoots and whole plantlets can be subsequently regenerated from the callus and, for this reason, a precise control of callus formation and regeneration is critical for tissue culture and transformation technologies. Through a chemical screen, Nakano et al (2018) identified fipexide (FPX) as a potent inducer of dedifferentiation and callus formation. A transcriptomic analysis of FPX-induced/repressed genes revealed shared and unique effects of FPX and auxin/cytokinin treatments.…”