The study performed transcriptome profiling of Cryptomeria japonica individuals from different geographic origins grown in three common gardens across Japan, assembling 77,212 transcripts guided by the species' genome. Using SNP-based genetic clustering and weighted gene co‑expression network analysis, they identified gene modules whose expression correlated with genetic differentiation, revealing that defense‑related genes are up‑regulated in Pacific‑side populations while terpenoid metabolism genes are higher in Sea‑of‑Japan populations, indicating local adaptation via regulatory changes.

The study demonstrates that abscisic acid (ABA) accumulates in darkness to suppress cotyledon opening during seedling deetiolation, and that light exposure lifts this repression, enabling cotyledon aperture. Genome‑wide transcriptional and alternative‑splicing changes accompany this process, and the light‑dependent regulation requires the splicing factors RS40 and RS41, whose activity is repressed in the dark.