Pulled GA signal orchestration proteome reconfiguration and redundancy cycling via PtGA2ox10-mediated metabolic gatekeeping in Chinese pine seeds.

Abstract

Key message: This study reveals the molecular mechanisms of seed dormancy and germination in Chinese pine, highlighting the key roles of GA and ABA pathways and specific genes in regulating germination, growth, and stress resistance. Chinese pine (Pinus tabuliformis) is an ecologically and economically vital conifer species in China, serving critical functions in forest regeneration, soil conservation, and carbon sequestration. Despite its ecological importance, the molecular mechanisms governing seed dormancy release and germination in this species remain poorly understood. Using an integrative approach that combines advanced microscopy, hormone profiling, metabolomics, and whole transcriptome sequencing, we uncovered novel molecular insights into these crucial developmental processes. Optical and transmission electron microscopy revealed that protein bodies aggregated in aleurone cells during dormancy release. High-performance liquid chromatography-mass spectrometry (HPLC-MS) analysis revealed distinct hormonal antagonism: gibberellin (GA) levels peaked during dormancy release (S2), with GA3 increased by 8.1-fold (from 41.37 ± 8.68 ng/g to 336.97 ± 106.14 ng/g), whereas abscisic acid (ABA) decreased by 63.6% (from 54.39 ± 1.83 ng/g at S1 to 19.80 ± 0.73 ng/g at S3), which negatively correlated with seed germination. Moreover, these hormonal changes were accompanied by profound metabolic reprogramming, which included a 6.0-fold increase in fructose content and a 12.3-fold increase in glucose content, whereas sucrose levels decreased by 48.1%, indicating enhanced carbohydrate mobilization during the germination phase (S3). Importantly, our transcriptomic analyses identified three novel regulatory genes (PtGA2ox10, PtRGA1, and PtABI2) with distinct expression patterns and functional roles during dormancy-germination transitions. Most significantly, we provide the first experimental evidence that PtGA2ox10 plays a dual regulatory role in both germination control and stress response pathways, a previously unrecognized function in conifers. These findings fundamentally advance our understanding of pine seed biology and establish new research directions in conifer molecular physiology.