Genome-wide identification of geranylgeranyl diphosphate synthase (GGPPS) gene family and functional characterization of PmGGPPS14 in Pinus massoniana

Pinus massoniana Lamb. is the primary commercial resin-producing conifer in China. Its oleoresin, a complex mixture of diverse terpene metabolites, is a high-value industrial feedstock for rosin and turpentine production, while also functioning as a key defensive metabolite mediating pine stress resistance. Geranylgeranyl pyrophosphate synthase (GGPPS), the rate-limiting enzyme in the diterpenoid biosynthetic pathway, not only modulates plant growth and development, but has also been well documented to be tightly linked to pine wood nematode (PWN) resistance and resin yield in P. massoniana . In this study, we identified 15 PmGGPPS genes from the P. massoniana genome and conducted a comprehensive systematic analysis. Expression pattern analysis revealed that six PmGGPPS genes were significantly induced by PWN infection. These genes exhibited distinct tissue-specific expression profiles, and also responded to hormone treatments and various stress challenges in P. massoniana . Furthermore, we validated that PmGGPPS14 encodes a functional geranylgeranyl diphosphate (GGPP) synthase. Functional assays via virus-induced gene silencing (VIGS) in P. massoniana and heterologous expression in Arabidopsis thaliana revealed that PmGGPPS14 is a key regulator of both photosynthetic pigment biosynthesis in pine needles and diterpene resin acid production. Additionally, yeast two-hybrid (Y2H) screening identified nine interacting protein partners of PmGGPPS14 . This study advances the functional understanding of the GGPPS gene family in conifers, and provides a theoretical foundation for the molecular breeding of elite P. massoniana with enhanced stress resistance and high resin yield.