Multi-omics integration analysis of leaves reveals the adaptive survival mechanism of Carpinus oblongifolia, an endemic tree species in subtropical forests of eastern China.

INTRODUCTION: The soils of subtropical forests are generally limited by P availability, and over time the P limitation experienced by the tree species becomes increasingly severe. The plasticity of leaf traits and the reprogramming of metabolites are strategies for plants to adapt to environmental stress, including P limitation. However, research that link the plasticity of leaf traits, gene regulation, and metabolism to reveal the adaptive survival mechanisms to P limitation is still relatively scarce. METHODS: The structural and chemical traits, transcriptomics, and metabolomics of the leaves of an endemic species, Carpinus oblongifolia (Betulaceae), naturally growing in a P-limited subtropical forest of eastern China, were investigated. RESULTS AND DISCUSSION: P limitation and pH was the predominant soil factor driving the variation in leaf traits of C. oblongifolia. The plasticity of leaf thickness (LT) was the core ecological strategy for this species to adapt to P-limited habitats and leaf thickening was closely related to the accumulation of secondary metabolites. Further, through integrated analysis of transcriptomics and metabolomics, the regulatory network involving four hub genes and five metabolites was constructed to mediate leaf thickening. The coordinated adaptation in leaf structure and metabolism achieves a balance between resource utilization efficiency and stress tolerance, which were the adaptive survival mechanisms of C. oblongifolia in P-limited subtropical forest ecosystems. This study has for the first time revealed the adaptive survival mechanisms of C. oblongifolia, providing a new perspective on ecological restoration, conservation planning, and genetic resource management of a species with small population under global climate change.