Transcriptome Profiling Revealed Light-Mediated Gene Expression Patterns of Plants in Forest Vertical Structures

Light is a critical environmental factor that shapes forest communities. The canopy trees intercept the light, thus understory plants become shaded. Shade leads to the attenuation of light intensity and a shift in the spectrum through the forest vertical structure. The capacity of forest trees to survive and grow under conditions of light heterogeneity is closely related to the intrinsic property of these species. Therefore, identifying how plants interact with light-regime variability is an important research objective of community ecology. In this study, we investigated the light-mediated gene expression patterns in forest vertical structures utilizing transcriptome profiling. The expression levels of 20 annotated genes closely related to photosynthesis, light receptors, and photoprotection were used as traits to estimate how variable light environments influence the plants in forest vertical structures. In summary, the shade-tolerant species were characterized by higher levels of photoreceptor (phot1/2 and phyA/B), photorespiration (pglp1/2), and photoprotection genes (Lhca5, Lhca7, and PsbS and photolyases), but with a lower abundance of photosynthetic light-harvesting genes (Lhca1/2 and Lhcb1/2). Also, the expression of light-harvesting and photoprotection genes were generally up-regulated by intense light, while the expression of photoreceptor genes was up-regulated by shade. This research highlights how differential plant responses to light shape the vertical structure of plant communities in a subtropical forest.