Molecular Regulatory Mechanisms Underlying Leaf Color Transitions in Pyrus betulaefolia Bunge under High Light Intensity Stress

Pyrus betulaefolia is a significant species within the Pyrus genus and serves as a crucial rootstock for commercial pear cultivation. While leaf coloration is a common phenomenon in nature, the specific mechanisms driving this change in P. betulaefolia remain underexplored. This study investigated leaf color dynamics in P. betulaefolia , revealing that leaves turned red following 12 days of exposure to intense white light. Subsequently, exposure to natural light for 9 days induced the red leaves to revert to green. Measurements of chlorophyll fluorescence and pigment content indicated that the reddened leaves exhibited significantly increased non-photochemical quenching (NPQ) and elevated synthesis of chlorophyll a, anthocyanins, and carotenoids, thereby enhancing their tolerance to high-intensity white light. Transcriptome analysis of the red leaves demonstrated a marked upregulation of light-harvesting complex (LHC) proteins, as well as proteins related to carotenoid and chlorophyll metabolism. Furthermore, transcription factor analysis identified 18 transcription factors potentially involved in regulating these pigment changes.