Bhati, K. K. | bioRxiv Science

bioRxiv2022

The m6A writer FIONA1 methylates the 3'UTR of FLC and controls flowering in Arabidopsis

Adenosine bases of RNA can be transiently modified by the deposition of a methyl-group to form N6-methyladenosine (m6A). This adenosine-methylation is an ancient process and the enzymes involved are evolutionary highly conserved. A genetic screen designed to identified suppressors of late flowering transgenic Arabidopsis plants overexpressing the miP1a microProtein yielded a new allele of the FIONA1 (FIO1) m6A-methyltransferase. To characterize the early flowering phenotype of fio1 mutant plants we employed an integrative approach of mRNA-seq, Nanopore direct RNA-sequencing and meRIP-seq to identify differentially expressed transcripts as well as differentially methylated mRNAs. We provide evidence that FIO1 is the elusive methylase responsible for the 3-end methylation of the FLOWERING LOCUS C (FLC) transcript. Furthermore, our genetic and biochemical data suggest that 3-methylation stabilizes FLC mRNAs and non-methylated FLC is a target for rapid degradation.

plant biology↗

bioRxiv2019

Wheat inositol pyrophosphate kinase (TaVIH2-3B) interacts with Fasciclin-like arabinogalactan (FLA6) protein and alters the plant cell-wall composition

BackgroundInositol pyrophosphates (PP-InsPs) are high-energy cellular molecules involved in different signalling and regulatory responses. Two distinct classes of inositol phosphate kinases responsible for the synthesis of PP-InsPs have been identified in Arabidopsis i.e. ITPKinase (inositol 1,3,4 trisphosphate 5/6 kinase) and PP-IP5Kinase (diphosphoinositol pentakisphosphate kinases). Plant PP-IP5Ks are capable of synthesizing InsP8 and were shown to control pathogenic defence and phosphate response signals. However, other roles offered by plant PP-IP5Ks, especially towards abiotic stress, remain poorly understood. ResultsHere, we characterized two Triticum aestivum L. (hexaploid wheat) PPIP5K homologs, TaVIH1 and TaVIH2, for their physiological functions. We demonstrated that wheat VIH proteins could utilize InsP7 as the substrate to produce InsP8, a process that requires the functional VIH-kinase domains. At the transcriptional level, both TaVIH1 and TaVIH2 are expressed in different wheat tissues, including developing grains, but show selective response to abiotic stresses during drought-mimic experiments. Overexpression of TaVIH2-3B homolog in Arabidopsis conferred tolerance to drought stress and rescued the sensitivity of Atvih2 mutants. RNAseq analysis of TaVIH2-3B transgenic lines of Arabidopsis showed a genome-wide reprogramming with remarkable effects on cell-wall biosynthesis genes with enhanced the accumulation of polysaccharides (arabinogalactan, cellulose and arabinoxylan). ConclusionsOverall, this work identifies a novel function of VIH proteins, implying their roles in modulating cell-wall homeostasis genes and providing water-deficit stress tolerance. This work suggests that the plant VIH enzymes could be linked to drought tolerance and also opens up investigations to address the roles of plant VIH derived products in generating drought resistant plants.

plant biology↗