Landscape of RNA NAD+ capping in Arabidopsis unopened flower bud

Eukaryotic messenger RNAs (mRNAs) possess a 5’-end N7-methyl guanosine (m7G) cap that promotes their translation and stability. However, it was recently demonstrated that eukaryotic mRNAs can also carry a 5' end nicotinamide adenine dinucleotide (NAD+) cap that promotes mRNA decay mediated by the NAD+ decapping enzyme DXO1. However, the dynamic regulation of NAD+ capping in plant remains unknown. Here, we describe the global landscape of NAD+-capped RNAs in Arabidopsis thaliana, and demonstrate that DXO1 is responsible for removal of these 5’-end modifications and facilitates mRNA degradation in plant transcriptomes. We also reveal that in the absence of DXO1 NAD+-capped mRNAs are unstable and processed into smRNAs. Furthermore, we find that Abscisic Acid (ABA) remodel the landscape of RNA cap epitransciptome, and the mRNA lost their NAD+ cap contribute to their stability under ABA. Overall, our results support a link between ABA response and RNA NAD+ capping. NADseq, GMUCT and small RNA profiling in unopened flower bud of Arabidopsis thaliana