J Integr Plant Biol. ›› 2021, Vol. 63 ›› Issue (3): 570-582.DOI: 10.1111/jipb.13009

Special Issue: Development Abiotic stress Crop yield Epigenetics Hormone signaling Seed development Grain quality

• Research Articles • Previous Articles     Next Articles

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

Le Nguyen Tieu Ngoc1,2, Su Jung Park1, Trinh Thi Huong1, Kwang Ho Lee3 and Hunseung Kang1*   

  1. 1Department of Applied Biology, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186, Republic of Korea
    2Faculty of Forestry Agriculture, Tay Nguyen University, BuonMaThuotDakLak, 63000, Vietnam
    3Center for Research Facilities, Chonnam National University, Gwangju 61186, Republic of Korea

    *Correspondence: Hunseung Kang (hskang@jnu.ac.kr)
  • Received:2020-08-20 Accepted:2020-09-01 Online:2020-09-02 Published:2021-03-01

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.

Editorial Office, Journal of Integrative Plant Biology, Institute of Botany, CAS
No. 20 Nanxincun, Xiangshan, Beijing 100093, China
Tel: +86 10 6283 6133 Fax: +86 10 8259 2636 E-mail: jipb@ibcas.ac.cn
Copyright © 2022 by the Institute of Botany, the Chinese Academy of Sciences
Online ISSN: 1744-7909 Print ISSN: 1672-9072 CN: 11-5067/Q