*2.1. Anthocyanin Accumulation Patterns in Phalaenopsis 'Panda'*

The examination by light microscope showed that anthocyanin accumulated in the upper epidermal cells of spot area, while no anthocyanin accumulated in cells in non-spot area (Figure 1A–C). This result indicated that the visible spots resulted from accumulation of anthocyanin in cells of the upper epidermis. Furthermore, the anthocyanin content of the spot in *Phalaenopsis* 'panda' sepals was significantly different from that of the sepal according to the results by the UV-visible spectrophotometer scanning detection (Figure 1D,E). Anthocyanin content measured by the pH differential method revealed that high content of anthocyanin (1.0798 mg/g) was accumulated in spot area, while was barely detectable in the acyanic parts extraction.

**Figure 1.** Anatomical structures and anthocyanin content of *Phalaenopsis* 'Panda' sepal. (**A**) Sepal (bar = 1 cm); (**B**) Upper epidermal cell in spot area (bar = 10 μm); (**C**) Upper epidermal cell in non-spot area (bar = 10 μm); (**D**) UV-visible spectrophotometer scanning of non-spot area; (**E**) UV-visible spectrophotometer scanning of spot area. Red number of 531 nm represents the absorption wavelength of anthocyanin.
