bims-plasge Biomed News
on Plastid genes
Issue of 2018‒12‒09
four papers selected by
Vera S. Bogdanova
Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences

  1. Plant Cell Physiol. 2018 Nov 30.
      Pentatricopeptide repeat (PPR) proteins regulate organellar gene expression in plants, through their involvement in organellar RNA metabolism. In rice (Oryza sativa), 477 genes are predicted to encode PPR proteins; however, the majority of their functions remain unknown. In this study, we identified and characterized a rice mutant, pale-green leaf12 (pgl12); at the seedling stage, pgl12 mutants had yellow-green leaves, which gradually turned pale green as the plants grew. The pgl12 mutant had significantly reduced chlorophyll contents and increased sensitivity to changes in temperature. A genetic analysis revealed that the pgl12 mutation is recessive and located within a single nuclear gene. Map-based cloning of PGL12, including a transgenic complementation test, confirmed the presence of a base substitution (C to T), generating a stop codon, within LOC_Os12g10184 in the pgl12 mutant. LOC_Os12g10184 encodes a novel PLS-type PPR protein containing 17 PPR motifs and targeting to the chloroplasts. A qRT-PCR analysis showed that PGL12 was expressed in various tissues, especially the leaves. We also showed that the transcript levels of several nuclear- and plastid-encoded genes associated with chloroplast development and photosynthesis were significantly altered in pgl12 mutants. The mutant exhibited defects in the 16S rRNA processing and splicing of the plastid transcript ndhA. Our results indicate that PGL12 is a new PLS-type PPR protein required for proper chloroplast development and 16S rRNA processing in rice.
  2. Mol Phylogenet Evol. 2018 Nov 30. pii: S1055-7903(18)30453-6. [Epub ahead of print]
      Cycloidea-like (CYC-like) genes are the key regulatory factors in the development of flower symmetry. Duplication and/or reduction of CYC-like genes have occurred several times in various angiosperm groups and are hypothesized to be correlated with the evolution of flower symmetry, which in turn has contributed to the evolutionary success of these groups. However, less is known about the evolutionary scenario of CYC-like genes in the whole Fabales, which contains four families with either symmetric or actinomorphic flowers. Here we investigated the evolution of CYC-like genes in all the four families of Fabales and recovered one to four CYC-like genes (CYC1, CYC2, and CYC3) depending on which lineages, but the CYC3 genes were most likely lost in Leguminosae. Phylogenetic analysis suggested that the CYC-like genes could have undergone multiple duplications and losses in different plant lineages and formed distinct paralogous/orthologous clades. The ancestor of the Papilionoideae and Caesalpinioideae may possess two paralogs of CYC1 genes but one of them was subsequently lost in Papilionoideae and was retained only in several species of Caesalpinioideae. CYC2 genes were more frequently duplicated in Papilionoideae than in other legumes. We propose that the diversification patterns of both CYC1 and CYC2 genes are not related to the floral symmetry in non-papilionoid Fabales groups, however, gene duplication and functional divergence of CYC2 are essential for the floral zygomorphy of Papilionoideae. This is the first systematic analysis of the CYC-like genes in Fabales and could form the basis for further study of molecular mechanisms controlling floral symmetry in non-model plants of Fabales.
    Keywords:  Cycloidea-like genes; Duplication; Fabales, Leguminosae; Floral symmetry
  3. Plant Genome. 2018 Nov;11(3):
      Plant genomes reduce in size following a whole-genome duplication event, and one gene in a duplicate gene pair can lose function in absence of selective pressure to maintain duplicate gene copies. Maize ( L.) and its sister genus, , share a genome duplication event that occurred 5 to 26 million years ago. Because few genomic resources for exist, it is unknown whether grasses and maize have maintained a similar set of genes that have resisted decay into pseudogenes. Here we present high-quality de novo transcriptome assemblies for two species: (L.) L. and Porter ex Vasey. Genes with experimental protein evidence in maize were good candidates for genes resistant to pseudogenization in both genera because pseudogenes by definition do not produce protein. We tested whether 15,160 maize genes with protein evidence are resisting gene loss and whether their homologs are also resisting gene loss. Protein-encoding maize transcripts and their homologs have higher guanine-cytosine (GC) content, higher gene expression levels, and more conserved expression levels than putatively untranslated maize transcripts and their homologs. These results suggest that similar genes may be decaying into pseudogenes in both genera after a shared ancient polyploidy event. The transcriptome assemblies provide a high-quality genomic resource that can provide insight into the evolution of maize, a highly valuable crop worldwide.
  4. BMC Plant Biol. 2018 Dec 05. 18(1): 332
      BACKGROUND: In flowering plants, lipid biosynthesis and transport within anthers is essential for male reproductive success. TaMs1, a dominant wheat fertility gene located on chromosome 4BS, has been previously fine mapped and identified to encode a glycosylphosphatidylinositol (GPI)-anchored non-specific lipid transfer protein (nsLTP). Although this gene is critical for pollen exine development, details of its function remains poorly understood.RESULTS: In this study, we report that TaMs1 is only expressed from the B sub-genome, with highest transcript abundance detected in anthers containing microspores undergoing pre-meiosis through to meiosis. β-glucuronidase transcriptional fusions further revealed that TaMs1 is expressed throughout all anther cell-types. TaMs1 was identified to be expressed at an earlier stage of anther development relative to genes reported to be necessary for sporopollenin precursor biosynthesis. In anthers missing a functional TaMs1 (ms1c deletion mutant), these same genes were not observed to be mis-regulated, indicating an independent function for TaMs1 in pollen development. Exogenous hormone treatments on GUS reporter lines suggest that TaMs1 expression is increased by both indole-3-acetic acid (IAA) and abscisic acid (ABA). Translational fusion constructs showed that TaMs1 is targeted to the plasma membrane.
    CONCLUSIONS: In summary, TaMs1 is a wheat fertility gene, expressed early in anther development and encodes a GPI-LTP targeted to the plasma membrane. The work presented provides a new insight into the process of wheat pollen development.
    Keywords:  Glycosylphosphatidylinositol-anchored lipid transfer protein; LTP; Male sterility; Pollen exine; Sporopollenin; Wheat