Related Experiment Video
Updated: Jan 16, 2026
Discrimintion and Mapping of the Primary and Processed Transcripts in Maize Mitochondrion Using a Circular RT-PCR-based Strategy
Published on: July 29, 2019
Genomic-Encoded Mitovirus RdRp Is Required for Embryo Development and Maintaining Mitochondrial Dynamics in
Yadi Gong1, Rongqin Chen1, Chen Yang1
1Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Science, South China Normal University, Guangzhou 510631, China.
Abstract:
Mitoviral-derived sequences are frequently detected in plant genomes, encoding an RNA-dependent RNA polymerase (RdRp). These sequences share many similarities with mitoviruses that are known to commonly infect plant mitochondria. However, the functional characterization of nuclear-encoded mitoviral-RdRp remains unclear. This study elucidates the critical role of mRdRp (AT2G07749) in maintaining mitochondrial homeostasis and embryo viability, highlighting the dual role of viral-derived genes in plant development and stress response. Phylogenetic analysis reveals that mRdRp shares 96.8% identity with the mitoviral RdRp encoded by mitochondrial-genomes, suggesting that this nuclear mRdRp gene originated from horizontal transfer events following ancestral plant-mitovirus infections. To dissect mRdRp function, we generated a mRdRp knockout mutant via CRISPR-Cas9 or knockdown mutant by RNA interference (RNAi). These mRdRp mutants exhibited severe developmental defects, including dwarfism, embryo lethality, and sterility. Phenotypic assays further showed that mRdRp mutants displayed heightened susceptibility to ABA and rotenone, indicating impaired adaptive capacity to both hormonal and metabolic stress. Loss of mRdRp led to fragmented mitochondrial networks and a significant reduction in mitochondrial abundance in both leaf protoplasts and root meristematic cells. Additionally, mitochondrial-derived small RNA (sRNA) aberrantly accumulated in mRdRp mutants, which potentially disrupts endogenous RNA-silencing pathways that rely on sRNA-mediated gene regulation. Collectively, these results provide mechanistic insights into the function integration of a virus-derived gene into plant cellular networks, advancing our understanding of host-virus coevolution and the role of horizontally transferred viral genes in shaping plant physiology.
Insights
A nuclear-encoded viral gene, mRdRp, is crucial for plant mitochondrial health and embryo development. Loss of this gene impairs stress response and disrupts RNA silencing, revealing its vital role in plant physiology.
Area of Science:
- Plant Biology
- Virology
- Genetics
Background:
- Nuclear genomes often contain sequences derived from mitoviruses, encoding RNA-dependent RNA polymerase (RdRp).
- The function of these nuclear-encoded viral RdRp proteins in plants remains largely uncharacterized.
- Mitoviruses are known to infect plant mitochondria, but the integration of viral genes into host nuclear genomes is of significant interest.
Purpose of the Study:
- To investigate the function of the nuclear-encoded mRdRp (AT2G07749) in plant development and mitochondrial homeostasis.
- To explore the origin and evolutionary significance of nuclear-encoded viral genes in plants.
- To understand the impact of mRdRp on plant stress responses and RNA silencing pathways.
Main Methods:
- Phylogenetic analysis to determine the evolutionary relationship between nuclear mRdRp and viral RdRp.
- CRISPR-Cas9 gene editing and RNA interference (RNAi) to generate mRdRp knockout and knockdown mutants.
- Phenotypic analysis of mutants under normal and stress conditions (ABA, rotenone), and assessment of mitochondrial morphology and abundance.
Main Results:
- mRdRp knockout/knockdown mutants exhibited severe developmental defects, including dwarfism, embryo lethality, and sterility.
- Mutants showed increased susceptibility to abscisic acid (ABA) and rotenone, indicating impaired stress adaptation.
- Loss of mRdRp resulted in fragmented mitochondrial networks, reduced mitochondrial abundance, and aberrant accumulation of mitochondrial small RNAs (sRNAs).
Conclusions:
- The nuclear-encoded mRdRp plays a critical role in maintaining mitochondrial homeostasis and embryo viability in plants.
- Horizontally transferred viral genes, like mRdRp, can be functionally integrated into host genomes, influencing plant development and stress responses.
- mRdRp's function is essential for normal plant physiology, potentially by regulating mitochondrial integrity and endogenous RNA silencing pathways.
More Related Videos
Related Concept Videos
02:59Animal Mitochondrial Genetics
01:19Translocation of Proteins into the Mitochondria
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
01:39Mitochondrial Protein Sorting
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
01:37Mitochondria