Abstract text: Although the Musashi family of RNA-binding proteins has been extensively studied in animal cells, plant Musashi-like (MSIL) proteins remain poorly characterized, despite sharing key structural and functional features, notably two RNA Recognition Motifs (RRMs) that enable mRNA binding and regulation.
In Arabidopsis, the double atmsil2/4 mutant exhibits several phenotypes, including a hanging stem (Kairouani et al. 2023). Biochemical analyses of the stem cell wall in atmsil2/4 revealed an increased level of methylated glucuronic acid, which is associated with overexpression of the xylan methylation enzyme GXM3. These results suggest that AtMSIL2/4 redundantly regulate stem cell wall development, notably through the control of glucuronoxylan 4-O-methylation.
To assess the conservation of MSIL function across plant species, MSIL proteins are being studied in Brachypodium, a grass with a type II cell wall distinct from Arabidopsis. Four BdMSIL genes have been identified and structurally characterized, and phylogenetic analyses were performed. Single and double mutants targeting the most highly expressed BdMSIL genes were generated using CRISPR-Cas9. The lines were then genotyped and the most representative ones selected for further analyses. Biochemical characterization of MSIL mutants cell walls will be presented, including sugar and lignin quantification, to identify metabolic alterations, with a particular focus on glucuronoxylan methylation.