Abstract: Geranylgeranyl diphosphate synthase (GGPS) is a constitutive enzyme in the terpenoid biosynthesis pathway and plays an important role in plant growth. Five putative gene sequences of GGPS were cloned by RACE and RT-RCR, and named as CsGGPS1-4 and CsGGPS9, respectively. Three allelic variants (CsGGPS9-1, CsGGPS9-2 and CsGGPS9-3) were detected for CsGGPS9, and phylogenetic analysis indicated CsGGPS9 was different from the others. Protein sequence analysis revealed that all CsGGPSs had a conserved polyprenyl_synt domain but no N-terminal signal peptide. Subcellular location predication showed that CsGGPS1, CsGGPS2 and CsGGPS4 might be located in chloroplast while CsGGPS2 and CsGGPS4 might be located in mitochondria. The 3D model of CsGGPSs were predicted by Swiss Model and combined with the ‘three floor’ model indicated that CsGGPS1, CsGGPS2 and CsGGPS4 were bona fide GGPS. CsGGPS3 was the small subunit of heterodimer GPS. Although CsGGPS9 shared a similar structure with the others, the main product of it could be isopentenyl pyrophosphate with chain length longer than 30. The qRT-PCR analysis showed that CsGGPS1 had low expression levels in all tissues except the ‘two and a bud’. By contrast, CsGGPS2 was highly expressed in all tissues with the highest levels in flowers, where in the expression levels increased first and then decreased during flower blooming. CsGGPS3 exhibited higher expression levels in the leaves and tender root than the flower. The expression levels of CsGGPS4 were similar in different tissues, with the same pattern as CsGGPS2 during flower blooming. CsGGPS9 was significantly higher expressed in the young leaves than the mature leaves.

Key words: tea plant (Camellia sinensis), geranylgeranyl diphosphate synthase, 3D structure model, expression analysis