Transcriptomic profiling of Arabidopsis primary root tips of brl3 mutant exposed to DNA damaging agent zeocin [RNA-seq]

Brassinosteroids (BRs) are steroid hormones involved in multiple processes of plant growth and development, and the adaptation to the environment. Some of the processes regulated by BRs are meristem activity and stem cell divisions. At the core of the root stem cell niche, it is placed the quiescent center (QC), that act as a cell reservoir. QC cells only trigger their divisions when need to replenish the stem cells, for example, after a DNA damage. BR signaling is in charge of triggering these QC divisions, but the exact mechanisms of how this process is regulated is still unknown. Here, we use an interdisciplinary approach, using Arabidopsis thaliana as a model system, including molecular genetics, physiology and bioinformatics to decipher the role of BR receptors upon DNA damage regulating the QC divisions. The results uncover novel roles for the BR-receptor kinase BRL3 (BRI1-like 3) receptor in DNA damage response (DDR) in plants, by modulating the DNA repair and the cell-cycle progression. We identified candidate tissue-specific transcriptional regulator, specifically expressed in the QC cells, the RNR2A (RIBONUCLEOTIDE REDUCTASE 2A), in charge of maintaining dNTPs (deoxynucleotide triphosphates) supply during DNA synthesis that is modulated by BRL3 downstream signaling events. Considering the importance of plant stem cells and their tissues for biomass accumulation and constantly exposed to adverse environmental stresses that can cause DNA damage or cell-cycle arrest in the RAM, here we stablished the mechanism linking root meristematic activity to the DDR through the cell-specific steroid receptor kinase BRL3. A two factor experimental design (Genotype and treatment). Primary root tips of 6-day-old Arabidopsis seedlings of Col-0 (WT) and brl3 mutant (SALK_006024C), in control conditions and treated with 2h 10µm zeocin. Three biological replicates per genotype and condition. A total of 12 samples, whose libraries were sequenced twice.