Transcriptional Regulation of Grapevine Bud Burst in Light and Dark Conditions

The transition from quiescence to bud burst is rapid, taking 3-5 days from completely enclosed bud to a fully open and photosynthetic organ. However, little is known about what process underlining during grapevine buds transition. Here, we studied a developmental time course of bud burst grown in a light/dark photoperiod (0h, 24h, 72h and 144h) and continuous darkness (0h, 3h 24h, 72h and 144h) to gain knowledge about the processes involved in grapevine bud burst (Crimson Seedless).

To investigate the requirement for light to enable viable bud burst, RNA-Seq experiment was done (FDR 0.01 and FC 3-fold). In both, light/dark photoperiod and continuous darkness were performed comparisons against 0h. Functional enrichment (FatiGO, P=0.01) was performed to each treatment.

Categories as cellular process, metabolism (cellular, primary and secondary), signaling, response to stimulus and transport overview were altered between treatments. Genes belonging to NAC family transcription were detected down-regulated whole time course in continuous darkness, whereas ERF genes related to AP2 family transcription factor were found in light/dark photoperiod. Remarkably, Circadian clock Signaling category was down-regulated in the early stages with a slight increased at 144h in both treatments. However, different genes built their profiles. Furthermore, C2C2-YABBY family transcription factor was detected up-regulated in light/dark treatment.

Altogether the data provides an overview of gene expression alteration due to light exposition in grapevine buds and how these treatments affected the initiation of bud burst. Suggesting a pivotal role of several functional categories as metabolism (primary and secondary) as well as transport overview.