Gene expression profiling of Arabidopsis arf2-6 mutant compared to Col-0 wildtype during dark-induced senescence

ABSTRACT: The aim of this experiment was to decipher a transcriptional regulatory code of Arabidopsis Auxin Response Factor 2 (ARF2) and understand the molecular basis of ARF2’s role as a promoter of dark-induced senescence. A combination of computational tools and yeast one-hybrid experiments identified potential direct transcriptional regulators of ARF2 belonging to several TF families including AP2/ERFs and AREB/ABF/ABI5s. Using ARF2 promoter mutants in transcriptional activation and Y1H experiments, the binding sites of these TFs in the ARF2 promoter were identified. AP2/ERFs including ERF1, ERF15 and ORA59 transactivate the ARF2 promoter in Arabidopsis mesophyll protoplasts and this transactivation is positively regulated by ABA. Crucially, the positive effect of ABA on ERF1 transactivation of ARF2 relies on the functional ABRE motif in the ARF2 promoter and the presence of AREB/ABF/ABI5s (ABF3 and ABF4) suggesting the existence of combinatorial regulation of ARF2 by these direct regulators. ABF3 and ABF4 were unable to activate the ARF2 promoter on their own indicating the necessity of ERF1 as a coupling TF for AREB/ABF/ABI5-driven regulation of ARF2. We also show that MED25 (a subunit of the Mediator complex) is required for proper transcriptional regulation of ARF2 during senescence. med25 plants show decreased ARF2 mRNA levels during natural senescence and, similarly to arf2-6 mutants, exhibit a delayed dark-induced senescence phenotype. We show that MED25 is important for ERF1-, ERF15- and ORA59-dependent transactivation of ARF2 in Arabidopsis protoplasts and finally idenitfy genes differentially expressed in arf2-6 mutants compared to wildtype during dark-induced senescence. Hence, we elucidate a regulatory network around ARF2 identifying combinatorial transcriptional regulation of this gene during senescence as well as likely downstream targets. The combinatorial regulation, comprised of AP2/ERFs and AREB/ABF/ABI5s TFs, enables integration of at least two key hormone signaling pathways to drive expression of a key senescence regulator.

ORGANISM(S): Arabidopsis thaliana

PROVIDER: GSE150569 | GEO | 2022/09/30

REPOSITORIES: GEO