RHE1 is associated with short-day-induced hypocotyl elongation, peroxisomal ROS homeostasis, and m 6A-dependent RNA stability in Arabidopsis.

Plants dynamically adjust growth in response to short-day (SD) conditions while maintaining reactive oxygen species (ROS) homeostasis across cellular compartments. However, how light signaling is coupled to organelle-specific redox regulation remains poorly understood. Here, we identify the peroxisomal Mpv17/PMP22 family protein REGULATOR OF ROS-MEDIATED HYPOCOTYL ELONGATION 1 (RHE1) as a regulator of short-day-induced hypocotyl elongation and ROS homeostasis in Arabidopsis thaliana. RHE1 expression is associated with a light-responsive G-box element bound by HY5 and shows a strong positive relationship with N6-methyladenosine (m6A) enrichment. Environmental stresses that elevate inferred m6A levels increase RHE1 transcript abundance and stability, whereas short-day conditions reduce m6A enrichment and decrease RHE1 expression. Loss of RHE1 results in enhanced hypocotyl cell elongation and elevated ROS accumulation specifically under short-day conditions, indicating that RHE1 constrains growth through peroxisomal redox regulation. Furthermore, RHE1 transcript levels correlate with the m6A reader ECT2, and published binding datasets support direct association of ECT2 with RHE1 mRNA. Together, these findings reveal a multilayered regulatory mechanism in which HY5-associated transcription and m6A-dependent RNA stabilization converge on RHE1 to coordinate SD-dependent growth with peroxisomal ROS homeostasis. This study uncovers a previously unrecognized connection between SD signaling, epitranscriptomic regulation, and organelle-specific redox control.