bims-plasge Biomed News
on Plastid genes
Issue of 2020‒07‒19
two papers selected by
Vera S. Bogdanova
Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences

  1. Rice (N Y). 2020 Jul 11. 13(1): 45
      BACKGROUND: The plant chloroplast is essential for photosynthesis and other cellular processes, but an understanding of the biological mechanisms of plant chloroplast development are incomplete.RESULTS: A new temperature-sensitive white stripe leaf 9(wsl9) rice mutant is described. The mutant develops white stripes during early leaf development, but becomes green after the three-leaf stage under field conditions. The wsl9 mutant was albinic when grown at low temperature. Gene mapping of the WSL9 locus, together with complementation tests indicated that WSL9 encodes a novel protein with an HNH domain. WSL9 was expressed in various tissues. Under low temperature, the wsl9 mutation caused defects in splicing of rpl2, but increased the editing efficiency of rpoB. Expression levels of plastid genome-encoded genes, which are transcribed by plastid-coded RNA polymerase (PEP), chloroplast development genes and photosynthesis-related genes were altered in the wsl9 mutant.
    CONCLUSION: WSL9 encodes an HNH endonuclease domain-containing protein that is essential for early chloroplast development. Our study provides opportunities for further research on regulatory mechanisms of chloroplast development in rice.
    Keywords:  Chloroplasts; Oryza sativa; RNA splicing
  2. BMC Genomics. 2020 Jul 13. 21(1): 480
      BACKGROUND: The genus Brassica mainly comprises three diploid and three recently derived allotetraploid species, most of which are highly important vegetable, oil or ornamental crops cultivated worldwide. Despite being extensively studied, the origination of B. napus and certain detailed interspecific relationships within Brassica genus remains undetermined and somewhere confused. In the current high-throughput sequencing era, a systemic comparative genomic study based on a large population is necessary and would be crucial to resolve these questions.RESULTS: The chloroplast DNA and mitochondrial DNA were synchronously resequenced in a selected set of Brassica materials, which contain 72 accessions and maximally integrated the known Brassica species. The Brassica genomewide cpDNA and mtDNA variations have been identified. Detailed phylogenetic relationships inside and around Brassica genus have been delineated by the cpDNA- and mtDNA- variation derived phylogenies. Different from B. juncea and B. carinata, the natural B. napus contains three major cytoplasmic haplotypes: the cam-type which directly inherited from B. rapa, polima-type which is close to cam-type as a sister, and the mysterious but predominant nap-type. Certain sparse C-genome wild species might have primarily contributed the nap-type cytoplasm and the corresponding C subgenome to B. napus, implied by their con-clustering in both phylogenies. The strictly concurrent inheritance of mtDNA and cpDNA were dramatically disturbed in the B. napus cytoplasmic male sterile lines (e.g., mori and nsa). The genera Raphanus, Sinapis, Eruca, Moricandia show a strong parallel evolutional relationships with Brassica.
    CONCLUSIONS: The overall variation data and elaborated phylogenetic relationships provide further insights into genetic understanding of Brassica, which can substantially facilitate the development of novel Brassica germplasms.
    Keywords:  Brassica; Cytoplasmic DNA; Cytoplasmic male sterility; Evolutionary relationship; Maternal origin; Rapeseed