Cross talk between plant photoreceptor signaling and chloroplast signaling: implications for physiological regulation.

This review focuses on the bidirectional integrated network formed by light signaling and photosynthesis, providing insights for research aimed at optimizing plant energy balance, resource allocation, and stress resilience to facilitate crop improvement. Photoreceptor-mediated light signaling constitutes the core pathway through which plants perceive light quality, intensity, and duration to precisely modulate growth and development. Crucially, this signaling network extensively interacts with and engages in cross talk with the photosynthetic system, forming a sophisticated regulatory circuit. This integration allows plants to balance energy harvest (photosynthesis) with energy consumption (growth and development), thereby optimizing resource allocation and stress resilience under fluctuating environmental conditions. This review systematically examines the key components and molecular mechanisms that define photoreceptor signaling over the past two decades, including phytochromes, cryptochromes, and downstream factors such as COP1, PIFs, and HY5. A central focus of this review is the bidirectional interaction mechanism between photoreceptor signaling and chloroplast function. In this context, bidirectional regulation refers to two interconnected processes: (i) anterograde control, in which nuclear photoreceptor signaling regulates chloroplast biogenesis, photosynthetic gene expression, and chloroplast positioning; (ii) retrograde signaling, whereby chloroplast functional status generates metabolic and redox-derived signals that feed back to the nucleus to reshape light signaling outputs. Importantly, emerging evidence suggests that these pathways do not operate independently but instead converge at shared transcriptional and signaling nodes, forming an integrated regulatory network that coordinates energy capture with growth and stress responses. Finally, the review summarizes major advances and open questions in light signaling theory, discusses innovative applications in intelligent, spectral-tunable lighting systems for controlled-environment agriculture, and offers future perspectives on applying light resource research to sustainable crop improvement.