Pan-Plastome Insights Into Genetic Adaptation and Future Distribution of Lycopus lucidus Under Climate Change

The medicinal perennial herb Lycopus lucidus Turcz. ex Benth. possesses significant phylogenetic and ecological value, yet its genetic diversity and adaptive mechanisms remain poorly understood. In this study, we constructed a pan-plastome based on 60 newly sequenced plastomes, revealing high structural conservation alongside substantial nucleotide diversity. Population genomic analyses identified two distinct lineages: an SD lineage adapted to the hot, arid Shandong Peninsula, and a non-SD lineage prevalent in warm, humid regions south of the Yangtze River. Mantel tests demonstrated that both geographic and environmental factors shape genetic differentiation. Notably, genome-wide scans detected signatures of adaptive variants in the psbD gene within the SD lineage, suggesting its critical role in adaptation to high-temperature and drought stress. Species distribution modeling using MaxEnt further highlighted precipitation as the dominant driver shaping the current distribution of L. lucidus. Highly suitable habitats are concentrated in Liaoning Province and the Yangtze River Basin, with moderate suitability across much of eastern China. Under future climate scenarios, suitable habitats are projected to expand, yet become increasingly fragmented-particularly in northern China and regions south of the Yangtze River. These findings provide novel insights into the adaptive evolution and ecological resilience of L. lucidus, offering a genetic basis for conservation strategies and sustainable utilization in the context of global climate change.