Uncovering the novel signaling components in warm temperature mediated regulation of transcriptome in Arabidopsis thaliana

Transcriptome analysis suggests that lrb123 and pif3 mutants have similar gene expression profiles with pif4 mutants, suggesting that LRBs and PIF3 have overlapping functions with PIF4. Further analysis revealed that most of the genes induced by PIF4 in a temperature-dependent manner are strongly downregulated. These genes belong to the Auxin/BR growth hormone pathways, wherein genes involved in auxin/BR biosynthesis and signalling are severely perturbed in response to 27°C compared to 22°C. These results indicate that LRBs and PIF3-mediated induction of PIF4 target genes in response to warm temperature is likely through PIF4. Moreover, our data also demonstrate that both LRBs and PIF3 inhibit the expression of light-responsive genes in response to warmth, further highlighting the role of LRBs and PIF3 in promoting thermomorphogenesis, is by directly promoting growth-responsive genes, and second by inhibiting light signalling genes. Together, we conclude that LRBs and PIF3 are novel components of the thermosensory pathway and are essential to promote themomorhogensis, likely by enhancing the PIF4 activity and down gene expression. Overall design: To understand the mechanism of regulation of thermomorphogenesis by LRB E3 ubiquitin ligases and PIF3 transcription factor, whole transcriptome (RNA-seq) analysis of lrb123 and pif3 were performed in comparison to the wild-type (Col-0) under normal and warm temperature conditions. Also, we compared their gene expression profiles with the pif4-101 mutant to know the extent of overlapping function in regulating temperature-mediated transcriptome.