2025-08-25 オークリッジ国立研究所(ORNL)
<関連情報>
天然ポプラ変種におけるS/Gリグニン単量体比率の緯度勾配を裏付ける要因 Factors underlying a latitudinal gradient in the S/G lignin monomer ratio in natural poplar variants
Weiwei Zhu, Jin Zhang, Pradeep Kumar Prabhakar, +12 , and Jaime Barros
Proceedings of the National Academy of Sciences Published:August 20, 2025
DOI:https://doi.org/10.1073/pnas.2503491122
Significance
Lignin is a phenolic polymer in plant cell walls that provides mechanical support and facilitates water and nutrient transport through the vascular system. While lignin composition is known to change in response to environmental factors, its natural variation and adaptive significance remain poorly understood. This study demonstrates a latitudinal gradient in lignin composition in 433 poplar trees collected from the natural range of this species along the Northwest coast of North America. We found a coordinated metabolic and transcriptional shift and identified a mutation in a cell wall laccase genetically associated with this geographical pattern. These findings advance our understanding of the ecological function of lignin across latitudes and offer insights for developing sustainable forestry and bioenergy practices.
Abstract
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 Populus trichocarpa 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 of xylem cell wall biosynthesis. Further molecular analysis identified a mutation in a cell wall laccase genetically associated with higher S/G ratios that predominate in trees from warmer lower latitudes. Collectively, our findings suggest that lignin heterogeneity arises from an evolutionary process enabling poplar adaptation to different climatic challenges.
