CDE4 encodes a pentatricopeptide repeat protein involved in chloroplast RNA splicing and affects chloroplast development under low‐temperature conditions in rice

• Published in: Journal of integrative plant biology 2021-10, Vol.63 (10), p.1724-1739
• Main Authors: Liu, Xinyong, Zhang, Xichun, Cao, Ruijie, Jiao, Guiai, Hu, Shikai, Shao, Gaoneng, Sheng, Zhonghua, Xie, Lihong, Tang, Shaoqing, Wei, Xiangjin, Hu, Peisong
• Format: Article
• Language: English
• Subjects: Arabidopsis Proteins; CDE4; Chlorophyll; Chlorophyll - metabolism; chloroplast development; Chloroplasts; Chloroplasts - physiology; Cloning; Genes; Guanylate kinase; Guanylate Kinases - metabolism; Kinases; low‐temperature; Mutants; Oryza - genetics; Oryza - metabolism; Oryza sativa; Oryza sativa L; pentatricopeptide repeat (PPR) protein; Phenotypes; Plant Development; Plant Proteins - genetics; Plant Proteins - metabolism; Proteins; Ribonucleic acid; Rice; RNA; RNA Splicing; RNA, Chloroplast - metabolism; Splicing; Temperature; Transcription
• ISSN: 1672-9072; 1744-7909
• DOI: 10.1111/jipb.13147

Pentatricopeptide repeat (PPR) proteins play important roles in the post‐transcriptional modification of organellar RNAs in plants. However, the function of most PPR proteins remains unknown. Here, we characterized the rice (Oryza sativa L.) chlorophyll deficient 4 (cde4) mutant which exhibits an albino phenotype during early leaf development, with decreased chlorophyll contents and abnormal chloroplasts at low‐temperature (20°C). Positional cloning revealed that CDE4 encodes a P‐type PPR protein localized in chloroplasts. In the cde4 mutant, plastid‐encoded polymerase (PEP)‐dependent transcript levels were significantly reduced, but transcript levels of nuclear‐encoded genes were increased compared to wild‐type plants at 20°C. CDE4 directly binds to the transcripts of the chloroplast genes rpl2, ndhA, and ndhB. Intron splicing of these transcripts was defective in the cde4 mutant at 20°C, but was normal at 32°C. Moreover, CDE4 interacts with the guanylate kinase VIRESCENT 2 (V2); overexpression of V2 enhanced CDE4 protein stability, thereby rescuing the cde4 phenotype at 20°C. Our results suggest that CDE4 participates in plastid RNA splicing and plays an important role in rice chloroplast development under low‐temperature conditions. The pentatricopeptide repeat protein CDE4 localizes in chloroplasts, where it is stabilized by VIRESCENT 2 and plays important roles in chloroplast RNA splicing, maintenance of chloroplast transcription/translation, and regulation of chloroplast development in rice under low‐temperature conditions.