N4‐methylcytidine ribosomal RNA methylation in chloroplasts is crucial for chloroplast function, development, and abscisic acid response in Arabidopsis

Abstract

Although the essential role of messenger RNA methylation in the nucleus is increasingly understood, the nature of ribosomal RNA (rRNA) methyltransferases and the role of rRNA methylation in chloroplasts remain largely unknown. A recent study revealed that CMAL (for Chloroplast mr aW‐ Like) is a chloroplast‐localized rRNA methyltransferase that is responsible for N4‐methylcytidine (m4C) in 16S chloroplast rRNA in Arabidopsis thaliana. In this study, we further examined the role of CMAL in chloroplast biogenesis and function, development, and hormone response. The cmal mutant showed reduced chlorophyll biosynthesis, photosynthetic activity, and growth‐defect phenotypes, including severely stunted stems, fewer siliques, and lower seed yield. The cmal mutant was hypersensitive to chloroplast translation inhibitors, such as lincomycin and erythromycin, indicating that the m4C‐methylation defect in the 16S rRNA leads to a reduced translational activity in chloroplasts. Importantly, the stunted stem of the cmal mutant was partially rescued by exogenous gibberellic acid or auxin. The cmal mutant grew poorer than wild type, whereas the CMAL‐overexpressing transgenic Arabidopsis plants grew better than wild type in the presence of abscisic acid. Altogether, these results indicate that CMAL is an indispensable rRNA methyltransferase in chloroplasts and is crucial for chloroplast biogenesis and function, photosynthesis, and hormone response during plant growth and development.

RNA methylation in plants: An overview

“…Along with this, chloroplast-to-nucleus signal affects the expression of plant hormone (GA, auxin, and ABA) signalingrelated genes. This study indicates that all these CMAL-mediated processes are essential for plant development and hormone signaling (Tieu Ngoc et al, 2021). Another study (Zou et al, 2020) in Arabidopsis showed that CMAL is involved in plant development by modulating auxin signaling pathways, in which authors uncovered the role of CMAL in ribosome biogenesis (Zou et al, 2020).…”

Comparative transcriptome profiling reveals the importance of GmSWEET15 in soybean susceptibility to Sclerotinia sclerotiorum

“…Although some abiotic stress responses have been reported, ribosome biogenesis can adapt to these stresses by increasing the transcript levels of respective key genes. However, the role of ribosome biosynthesis in plant immunity has rarely been reported ( Yu H. et al, 2020 ; Tieu Ngoc et al, 2021 ). In this study, compared to WT_24 h, gmsweet15 _24 h upregulated the abundance of genes related to ribosome biosynthesis ( Figures 4A , C ).…”

Boosting Clear Cell Renal Carcinoma-Specific Drug Discovery Using a Deep Learning Algorithm and Single-Cell Analysis

“…Besides their hydrogen bonding ability, they can also generate π-π interactions. The last compound is a cytosine nucleoside analogue, which has mechanisms to inhibit DNA methyltransferase (e.g., zebularine) and potential antimetabolic and antitumor activities [63]. It also has a comparatively stable binding pocket with the protein EPAS1 through more than four potential hydrogen bonds (Figure 8E).…”