Recent advances and biotechnological applications of RNA metabolism in plant chloroplasts and mitochondria

Abstract

The chloroplast and mitochondrion are semi-autonomous organelles that play essential roles in cell function. These two organelles are embellished with prokaryotic remnants and contain many new features emerging from the co-evolution of organelles and the nucleus. A typical plant chloroplast or mitochondrion genome encodes less than 100 genes, and the regulation of these genesˈ expression is remarkably complex. The regulation of chloroplast and mitochondrion gene expression can be achieved at multiple levels during development and in response to environmental cues, in which, RNA metabolism, including: RNA transcription, processing, translation, and degradation, plays an important role. RNA metabolism in plant chloroplasts and mitochondria combines bacterial-like traits with novel features evolved in the host cell and is regulated by a large number of nucleus-encoded proteins. Among these, pentatricopeptide repeat (PPR) proteins are deeply involved in multiple aspects of the RNA metabolism of organellar genes. Research over the past decades has revealed new insights into different RNA metabolic events in plant organelles, such as the composition of chloroplast and mitochondrion RNA editosomes. We summarize and discuss the most recent knowledge and biotechnological implications of various RNA metabolism processes in plant chloroplasts and mitochondria, with a focus on the nucleus-encoded factors supporting them, to gain a deeper understanding of the function and evolution of these two organelles in plant cells. Furthermore, a better understanding of the role of nucleus-encoded factors in chloroplast and mitochondrion RNA metabolism will motivate future studies on manipulating the plant gene expression machinery with engineered nucleus-encoded factors.

Graphical abstract

Keywords:

• RNA metabolism
• chloroplast
• mitochondrion
• RNA editing
• RNA splicing
• PPR

Acknowledgement

We apologize to colleagues whose work we were unable to include due to space limitations.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work is supported by the National Natural Science Foundation of China [Grant No. 32170556 to X.Z.]. X.Z. is supported by the Hundred-Talent Program of Zhejiang University and the Excellent Young Scientists Fund Program (Overseas) from National Natural Science Foundation of China. J.H. is supported by the Central Public-interest Scientific Institution Basal Research Fund, Tea Research Institute, Chinese Academy of Agricultural Sciences [Grant No. 1610212021002], National Key R&D Program of China [Grant No. 2021YFD1601101] and National Natural Science Foundation of China [Grant No. 32202552].