Ornamental glowing plants with FPs or nano-lanterns
Ornamental glowing plants would be available when the fluorescence or bioluminescence was bright enough. The reported bioluminescent plants are summaried and shown in Table 1 . The gene expression casstte of FPs are easily to be integrated into genome and FPs can accumulated enormously in plant cells, so it is feasible to generate fluorescent plants. For example, CpYGFP, a yellowish-green FP from marine planktonChiridius poppei , can be excited at 509 nm laser line and emission was collected at 517 nm which is a red-shifted visible light (Masuda et al. 2006). Commercial plants were transformed withCpYGFP gene, and green fluorescence was observed from the flowers when emission filter were used (Sasaki et al. 2014; Kishi-Kaboshi et al. 2017). Additionally, eYGFP and eYGFPuv, two derivatives of CpYGFP, were expressed in the flowers of another flowering plant, Petunia hybrida . Green fluorescence was macroscopically observed from the flowers with naked eyes, when they were illuminated with visible and ultraviolet LED, respectively. Among the various colors of flowers, white flowers contain less petal pigments, indicating that less exciation light and fluorescence would be absorbed. As a result, white flowers were chosen in these trials (Chin et al., 2018). Many FPs maintain fluorescent stability under acidic conditions, thus keeping high activity in the acidic intracellular environment of higher plants that pH approximately 4.5-7.2. To enhance fluorescence, nano-lanterns were introduced into plant cells. Recently, green enhanced nano-lantern gene was transferred into A. thaliana , which could be lightened under the excitation of blue light. The luminescence became remarkably brighter when the suitable substrate furimazine was added (Furuhata et al., 2020). These results indicate it is possible to obtain commercial ornamental fluorescent flowers. Characteristics of FPs provides the fluorescent plants a specific proposed implementations, such as dried fluorescent flowers and fluorescent plant specimens. It is reported that embedding in fine grained silica gels, the desiccated fluorescent flowers transferred with CpYGFP gene remained glowing for more than a year, because some FPs are capable to generate fluorescence without water (Sasaki et al., 2014). However, fluorescent plants utilized as alternative light sources for street or reading lamp in completely darkness is currently difficult, and these application might be satisfied by glowing plants with luciferase-luciferin bioluminescent systems.