bims-plasge 2023-11-19 papers

Plant Physiol. 2023 Nov 13. pii: kiad598. [Epub ahead of print]

DEFECTIVE KERNEL 56 functions in mitochondrial RNA editing and maize seed development.

Jie Zang, Tengfei Zhang, Zhaogui Zhang, Juan Liu, Huabang Chen.

Proper seed development is essential for achieving grain production, successful seed germination, and seedling establishment in maize (Zea mays). In the past few decades, pentatricopeptide repeat (PPR) proteins have been proven to play an essential role in regulating the development of maize kernels through post-transcriptional RNA modification of mitochondrial genes. However, the underlying mechanisms remain largely unknown. Here, we characterized a mutant of DEFECTIVE KERNEL 56 (DEK56) with defective kernels that exhibited arrested development of both the embryo and endosperm. Accordingly, we isolated DEK56 through a map-based cloning strategy, and found that it encoded an E-subgroup PPR protein located in the mitochondria. Dysfunction of DEK56 resulted in altered cytidine (C) -to- uridine (U) editing efficiency at 48 editing sites across 21 mitochondrial transcripts. Notably, the editing efficiency of the maturase-related (matR) -1124 site was substantially reduced or abolished in the dek56 mutant. Furthermore, we found that the splicing efficiency of NADH dehydrogenase subunit 4 (nad4) introns 1 and 3 was substantially reduced in dek56 kernels, which might be a consequence of the defective MatR function. Through a protein-protein interaction test, we hypothesized that DEK56 carries out its function by recruiting the PPR-DYW protein PPR motif, coiled-coil, and DYW domain-containing protein 1 (PCW1). This interaction is facilitated by Multiple Organellar RNA Editing Factors (ZmMORFs) and Glutamine-Rich Protein 23 (ZmGRP23). Based on these findings, we developed a working model of PPR-mediated mitochondrial processing that plays an essential role in the development of maize kernels. The present study will further broaden our understanding of PPR-mediated seed development and provide a theoretical basis for maize improvement.

Keywords: Maize; PPR gene; RNA editing; kernel development; mitochondrion

DOI: https://doi.org/10.1093/plphys/kiad598

Theor Appl Genet. 2023 Nov 18. 136(12): 248

Mapping of Rf20(t), a minor fertility restorer gene for rice wild abortive cytoplasmic male sterility in the maintainer line 'Zhenshan97B'.

Yang Liu, Zuopeng Xu, Yuanyue Du, Benxi Huang, Meng Li, Lijia Zhang, Xiangqiang Zhao, Qiaoquan Liu, Shuzhu Tang, Honggen Zhang.

Three-line hybrid rice has primarily been developed on wild abortive (WA)-type cytoplasmic male sterility (CMS) and has helped increase the yield of rice globally. The development of WA-type CMS lines and hybrids was expedited through the identification and mapping of the fertility restorer gene (Rf) in maintainers. This study observed fertile plants in WA-TianfengA/Zhenshan97B//TianfengB population, indicating that the maintainer line 'Zhenshan97B' should carry Rfs for WA-type CMS. Several advanced backcross populations were generated with the genetic background of the 'WA-TianfengA,' and the pollen fertility levels of the backcrossed individuals in BC3F1, BC4F1 and BC4F2 populations are governed by a new gene, Rf20(t), from 'Zhenshan97B.' Employing bulk segregant analysis of fertile and sterile pools from the BC4F1 population, Rf20(t) was genetically mapped to a candidate region on chromosome 10. Subsequently, Rf20(t) was located between RM24883 and RM24919 through recombination analysis of molecular markers using the BC4F2 population. Implementing a substitution mapping strategy, Rf20(t) was ultimately mapped to a 245-kb region between the molecular markers STS10-122 and STS10-126 and obtained the most likely candidate gene LOC_Os10g02650, which is predicted to encode pentatricopeptide repeat-containing (PPR) protein. These results enhance our understanding of the fertility restoration of WA-type CMS lines, facilitating the development of high-quality pairs of WA-type CMS and maintainer lines.

DOI: https://doi.org/10.1007/s00122-023-04486-9

Nat Commun. 2023 Nov 13. 14(1): 7333

Copy number variation of the restorer Rf4 underlies human selection of three-line hybrid rice breeding.

Zhe Zhao, Zhi Ding, Jingjing Huang, Hengjun Meng, Zixu Zhang, Xin Gou, Huiwu Tang, Xianrong Xie, Jingyao Ping, Fangming Xiao, Yao-Guang Liu, Yongyao Xie, Letian Chen.

Cytoplasmic male sterility (CMS) lines are important for breeding hybrid crops, and utilization of CMS lines requires strong fertility restorer (Rf) genes. Rf4, a major Rf for Wild-Abortive CMS (CMS-WA), has been cloned in rice. However, the Rf4 evolution and formation of CMS-WA/Rf system remain elusive. Here, we show that the Rf4 locus emerges earlier than the CMS-WA gene WA352 in wild rice, and 69 haplotypes of the Rf4 locus are generated in the Oryza genus through the copy number and sequence variations. Eight of these haplotypes of the Rf4 locus are enriched in modern rice cultivars during natural and human selections, whereas non-functional rf4i is preferentially selected for breeding current CMS-WA lines. We further verify that varieties carrying two-copy Rf4 haplotype have stronger fertility restoration ability and are widely used in three-line hybrid rice breeding. Our findings increase our understanding of CMS/Rf systems and will likely benefit crop breeding.

DOI: https://doi.org/10.1038/s41467-023-43009-4