Autoluminescence characteristics of 25 Phalaenopsis orchids following transient transformation with eFBP2

Engineering autoluminescent plants, especially horticultural crops, has recently emerged as a promising research area, with one current approach involving the transgenic introduction of fungal luciferin biosynthesis genes. Unlike the reported autoluminescent plants--which have small, inconspicuous and short-lived flowers, such as tobacco and petunia--Phalaenopsis orchids are ideal for engineering autoluminescent varieties due to their showy, long-lasting flowers. However, it remains unclear whether all Phalaenopsis orchids would become autoluminescent after being engineered with luciferase genes. Here, aiming to screen for suitable cultivars prior to transgenic experiments, we assess the autoluminescence characteristics of 25 representative Phalaenopsis cultivars after transient eFBP2 transformation, alongside several key morphological and biochemical traits. Our results demonstrate that autoluminescence characteristics are correlated with floral color lightness, organ textures and epidermal cell types. In contrast, the content of the substrates of luciferin--caffeic acid and tyrosine, and the infiltration ease of eFBP2-containing inoculation solution into floral organs after injection, have limited effects on autoluminescence characteristics. Autoluminescence intensity can be reasonably predicted using five floral traits investigated, as 80.4% of variation can be explained by these traits. Our study not only identifies specific Phalaenopsis cultivars with high potential for developing autoluminescent lines but also provides a selection framework applicable to other horticultural crops.