bims-plasge 2024-09-22 papers

Plant Cell Physiol. 2024 Sep 20. pii: pcae108. [Epub ahead of print]

Arabidopsis pentatricopeptide repeat protein GEND2 participates in mitochondrial RNA editing.

Yaqing Nie, Yan Li, Penglai Yuan, Chengyun Wu, Xiaoqing Wang, Chunfei Wang, Xiumei Xu, Zhenguo Shen, Zhubing Hu.

In Arabidopsis, RNA editing alters more than 500 cytidines (C) to uridines (U) in mitochondrial transcripts, a process involving the family of pentatricopeptide repeat (PPR) proteins. Here, we report a previously uncharacterized mitochondrial PLS-type PPR protein, GEND2, which functions in the mitochondrial RNA editing. The T-DNA insertion in the 5'-untranslated region of GEND2, referred to as gend2-1, results in defective root development compared to wild-type (WT) plants. A comprehensive examination of mitochondrial RNA editing sites revealed a significant reduction in the gend2-1 mutant compared to WT plants, affecting six specific mitochondrial RNA editing sites, notably within the mitochondrial genes CcmFn-1, RPSL2 and ORFX. These genes encode critical components of cytochrome protein maturation pathway, mitochondrial ribosomal subunit, and twin arginine translocation subunits, respectively. Further analysis of the transcriptional profile of the gend2-1 mutant and wild type revealed a striking induction of expression in a cluster of genes associated with mitochondrial dysfunction and regulated by ANAC017, a key regulator coordinating organelle functions and stress responses. Intriguingly, the gend2-1 mutation activated an ANAC017-dependent signaling aimed at countering cell wall damage induced by cellulose synthase inhibitors, as well as an ANAC017-independent pathway that retarded root growth under normal condition. Collectively, our findings identify a novel mitochondrial PLS-type PPR protein GEND2, which participates in the editing of six specific mitochondrial RNA editing sites. Furthermore, the gend2-1 mutation triggers two distinct pathways in plants: an ANAC017-dependent pathway and ANAC017-independent pathway.

Keywords: GEND2 ; Mitochondrial dysfunction ; PPR protein ; RNA editing

DOI: https://doi.org/10.1093/pcp/pcae108

Planta. 2024 Sep 20. 260(4): 102

The CsPPR gene with RNA-editing function involved in leaf color asymmetry of the reciprocal hybrids derived from Cucumis sativus and C. hystrix.

Lei Xia, Han Wang, Xiaokun Zhao, Qinzheng Zhao, Xiaqing Yu, Ji Li, Qunfeng Lou, Jinfeng Chen, Chunyan Cheng.

MAIN CONCLUSION: The leaf color asymmetry found in the reciprocal hybrids C. hystrix × C. sativus (HC) and C. sativus × C. hystrix (CH) could be influenced by the CsPPR gene (CsaV3_1G038250.1). Most angiosperm organelles are maternally inherited; thus, the reciprocal hybrids usually exhibit asymmetric phenotypes that are associated with the maternal parent. However, there are two sets of organelle genomes in the plant cytoplasm, and the mechanism of reciprocal differences are more complex and largely unknown, because the chloroplast genes are involved besides mitochondrial genes. Cucumis spp. contains the species, i.e., cucumber and melon, which chloroplasts and mitochondria are maternally inherited and paternally inherited, respectively, serving as good materials for the study of reciprocal differences. In this study, leaf color asymmetry was observed in the reciprocal hybrids (HC and CH) derived from C. sativus (2n = 14, CC) and C. hystrix (2n = 24, HH), where the leaves of HC were found to have reduced chlorophyll content, abnormal chloroplast structure and lower photosynthetic capacity. Transcriptomic analysis revealed that the chloroplast development-related genes were differentially expressed in leaf color asymmetry. Genetic analysis showed that leaf color asymmetry was caused by the maternal chloroplast genome. Comparative analysis of chloroplast genomes revealed that there was no mutation in the chloroplast genome during interspecific hybridization. Moreover, a PPR gene (CsaV3_1G038250.1) with RNA-editing function was found to be involved in the regulation of leaf color asymmetry. These findings provide new insights into the regulatory mechanisms of asymmetric phenotypes in plant reciprocal crosses.

Keywords: CsPPR ; Chloroplast genome; Cucumber; Interspecific hybridization; Maternal inheritance; Reciprocal difference

DOI: https://doi.org/10.1007/s00425-024-04513-z

Planta. 2024 Sep 20. 260(4): 100

Cytoplasmic male sterility-based hybrids: mechanistic insights.

Joorie Bhattacharya, Rahul B Nitnavare, Pooja Bhatnagar-Mathur, Palakolanu Sudhakar Reddy.

MAIN CONCLUSION: A comprehensive understanding of the nucleocytoplasmic interactions that occur between genes related to the restoration of fertility and cytoplasmic male sterility (CMS) provides insight into the development of hybrids of important crop species. Modern biotechnological techniques allow this to be achieved in an efficient and quick manner. Heterosis is paramount for increasing the yield and quality of a crop. The development of hybrids for achieving heterosis has been well-studied and proven to be robust and efficient. Cytoplasmic male sterility (CMS) has been explored extensively in the production of hybrids. The underlying mechanisms of CMS include the role of cytotoxic proteins, PCD of tapetal cells, and improper RNA editing of restoration factors. On the other hand, the restoration of fertility is caused by the presence of restorer-of-fertility (Rf) genes or restorer genes, which inhibit the effects of sterility-causing genes. The interaction between mitochondria and the nuclear genome is crucial for several regulatory pathways, as observed in the CMS-Rf system and occurs at the genomic, transcriptional, post-transcriptional, translational, and post-translational levels. These CMS-Rf mechanisms have been validated in several crop systems. This review aims to summarize the nucleo-mitochondrial interaction mechanism of the CMS-Rf system. It also sheds light on biotechnological interventions, such as genetic engineering and genome editing, to achieve CMS-based hybrids.

Keywords: CMS; Cytoplasmic male sterility; Hybrid development; Nucleo-mitochondrial interaction; Restorer-of-fertility genes; Rf

DOI: https://doi.org/10.1007/s00425-024-04532-w

Plant Sci. 2024 Sep 17. pii: S0168-9452(24)00290-5. [Epub ahead of print] 112263

Emerging roles of the C-to-U RNA editing in plant stress responses.

Yu-Xuan Hu, An Huang, Yi Li, David P Molloy, Chao Huang.

RNA editing is an important post-transcriptional event in all living cells. Within chloroplasts and mitochondria of higher plants, RNA editing involves the deamination of specific cytosine (C) residues in precursor RNAs to uracil (U). An increasing number of recent studies detail specificity of C-to-U RNA editing as an essential prerequisite for several plant stress-related responses. In this review, we summarize the current understanding of responses and functions of C-to-U RNA editing in plants under various stress conditions to provide theoretical reference for future research.

Keywords: Plant; RNA editing; Stress response

DOI: https://doi.org/10.1016/j.plantsci.2024.112263