PbGLR3.2 and PbGLR3.6 Glutamate Receptor-Like Channels Are Involved in Rhythmic Floral Scent Emission in Phalaenopsis bellina

Phalaenopsis bellina produces monoterpenes in floral tissues under light conditions and endogenous circadian regulation. This study found that during monoterpene emission, floral tissues exhibit distinct low-frequency oscillatory electrical signals (main peak at 1.563–1.953 mHz), which also show a diurnal rhythmic pattern. In addition, elevated calcium ion concentrations in floral tissues were found to be specifically correlated with floral scent emission in P. bellina. Application of calcium channel blockers not only abolished the electrical signals but also suppressed monoterpene emission and downregulated the expression of the key biosynthetic enzyme gene PbGDPS.

Since glutamate receptor-like channels (GLRs) are key calcium-permeable channels in plants, we further identified four GLR genes in the floral tissues of P. bellina. Among them, PbGLR3.2 and PbGLR3.6, which are localized at the plasma membrane, are highly expressed in floral organs, and their expression levels are positively correlated with PbGDPS and genes encoding floral scent-related transcription factors. Using RNA interference (RNAi) to reduce the expression of either PbGLR3.2 or PbGLR3.6 significantly decreased monoterpene biosynthesis and floral volatile emission.

In summary, this study demonstrates that PbGLR3.2 and PbGLR3.6 are key regulators of rhythmic floral scent emission, and that this process is closely linked to electrical signaling and calcium dynamics in floral tissues. These findings reveal a mechanistic connection between floral electrophysiology, calcium signaling, and volatile compound emission, providing new insights into the regulation of rhythmic floral scent release in plants.

Publication:

Ya-Lan Chang, Xiu-Ci Zhu, Tsun-Ying Chen, Chui Eng Wong, Tsyr-Huei Chiou, Pai-Hsiang Su, Fang-Yu Chang, Mei-Fen Jeng, Chung-Hsien Wu, Hao Yu, and Hong-Hwa Chen*. 2026. GLR channels are required for rhythmic scent emission in Phalaenopsis bellina. The Plant Journal 126, e70822. doi: 10.1111/tpj.70822

https://onlinelibrary.wiley.com/doi/10.1111/tpj.70822