Biology subjects

Blaakmeer, A.

Publications and source records attributed to Blaakmeer, A..

3 recordsLinked to original sources

bioRxiv2025

Point mutation in sensor triples zinc levels in Sorghum bicolor

Zinc (Zn) deficiency is widespread in agricultural soils and it is also a common nutritional problem in humans. We previously discovered a Zn Sensor Motif (ZSM) in the Arabidopsis F-bZIP transcription factors, bZIP19 and bZIP23, which impacts the concentration of Zn in Arabidopsis plants. Sorghum (Sorghum bicolor (L.) Moench) is one of the most important cereals crops worldwide and here, using a large-scale sorghum mutant library, we report the identification of variants with a ZSM point mutation. We show that a cysteine substitution in the ZSM of the sorghum bZIP19/23 homolog causes a three-fold increase in Zn levels in sorghum seeds with no visible developmental penalty. Our work provides the first evidence that modulating the F-bZIP ZSM is a promising strategy for Zn biofortification in crops. This discovery paves the way to generate Zn biofortified crops and alleviate the global problems of Zn deficient soils and Zn malnutrition.

plant biology↗

bioRxiv2024

A shade-responsive microProtein in the Arabidopsis ATHB2 gene regulates elongation growth and root development

Shade triggers widespread changes in transcript isoform production in Arabidopsis thaliana. Using 5' PEAT sequencing, we identified 377 candidate microprotein-encoding transcripts arising from alternative transcription start sites, including one located within the third exon of ATHB2, a class II HD-ZIP transcription factor central to shade avoidance. The encoded microprotein, ATHB2miP, lacks the DNA-binding homeodomain but retains the leucine zipper domain, through which it forms heterodimers with full-length ATHB2, inhibits its DNA-binding activity, and disrupts its localization to nuclear photobodies. Ectopic expression of ATHB2miP phenocopies loss of ATHB2, deregulating genes involved in auxin signaling, root development, and iron homeostasis. Complementation of the athb2 mutant with a construct carrying a silent mutation at the ATHB2miP start codon results in exaggerated hypocotyl elongation under both white light and shade, demonstrating that ATHB2miP is required to restrain excessive elongation growth. Immunoprecipitation mass spectrometry confirmed that this mutation redirects translation to alternative initiation sites, producing distinct proteoforms absent from wild-type plants. Additionally, ATHB2 suppresses iron uptake genes, and iron availability modulates shade growth responses in an ATHB2-dependent manner. Together, these findings establish ATHB2miP as a regulator of an ATHB2 feedback circuit that integrates light and nutritional signals to coordinate shoot elongation and root development.

plant biology↗

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↗