biostudies-literatureZhu WDOE | SC | Center for Bioenergy InnovationDOE | SC | Center for Bioenergy Innovation (CBI)e2503491122https://www.ebi.ac.uk/biostudies/studies/S-EPMC12403099biostudies-literatureUnknown122(34)The chemical composition of wood plays a pivotal role in the adaptability and structural integrity of trees. However, few studies have investigated the environmental factors that determine lignin composition and its biological significance in plants. Here, we examined the lignin syringyl-to-guaiacyl (S/G) ratio in members of a <i>Populus trichocarpa</i> population sourced from their native habitat and conducted a genome wide association study to identify genes linked to lignin formation. Our results revealed many significant associations, suggesting that lignin biosynthesis is a complex polygenic trait. Additionally, we found an increase in the S/G ratio from northern to southern geographic origin of the trees sampled, along with a corresponding metabolic and transcriptional reprogramming Proceedings of the National Academy of Sciences of the United States of AmericaFactors underlying a latitudinal gradient in the S/G lignin monomer ratio in natural poplar variants.PMC12403099DE-AC05-00OR22725Barros JPrabhakar PKParks JMZhang JChan YODavidson RBMuchero WCooper CJUrbanowicz BRShu MDixon RAWeber RAZhu WPanzade GTuskan GAJoshi TfalseFactors underlying a latitudinal gradient in the S/G lignin monomer ratio in natural poplar variants.The chemical composition of wood plays a pivotal role in the adaptability and structural integrity of trees. However, few studies have investigated the environmental factors that determine lignin composition and its biological significance in plants. Here, we examined the lignin syringyl-to-guaiacyl (S/G) ratio in members of a <i>Populus trichocarpa</i> population sourced from their native habitat and conducted a genome wide association study to identify genes linked to lignin formation. Our results revealed many significant associations, suggesting that lignin biosynthesis is a complex polygenic trait. Additionally, we found an increase in the S/G ratio from northern to southern geographic origin of the trees sampled, along with a corresponding metabolic and transcriptional reprogramming 2025-01-01T00:00:00Z2025 Aug2026-05-29T16:59:36.292Z2026-04-08T05:25:55.416ZS-EPMC124030994083341210.1073/pnas.2503491122