bims-plasge Biomed News
on Plastid genes
Issue of 2019‒09‒29
two papers selected by
Vera S. Bogdanova
Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences

  1. Yale J Biol Med. 2019 Sep;92(3): 499-510
      Chloroplasts (members of the plastid family) and mitochondria are central to the energy cycles of ecosystems and the biosphere. They both contain DNA, organized into nucleoids, coding for critical genes for photosynthetic and respiratory energy production. This review updates the cellular and molecular biology of how chloroplasts, mitochondria, and their genomes in Angiosperms are maintained; particularly in leaf development and maternal inheritance. Maternal inheritance is the common form of transmission to the next generation. Both organelles cannot be derived de novo. Proplastids during very early leaf development develop into chloroplasts with their characteristic thylakoid structure, with the nucleoids associated with the thylakoids. In cell divisions in the leaf primordia and very early leaf development, mitochondria and plastids are duplicated, their nucleoids replicated and segregated, and the population of mitochondria and plastids segregated to daughter cells using the cytoskeleton. To maintain their nucleoids, mitochondria must undergo fusion as well as fission. Chloroplasts are transmitted to the next generation as proplastids where they are maintained in the egg cell but eliminated from the sperm cells. Mitochondria in the apical meristem undergo massive mitochondrial fusion (MMF) prior to floral induction and subsequent maternal inheritance. MMF also occurs again in early germination. MMF encourages DNA repair and recombination, possibly as part of a quality control in each generation. As a further quality control in both chloroplasts and mitochondria, damaged organelles are removed by autophagy. Following consideration of the above, areas requiring further understanding are highlighted.
    Keywords:  Chloroplast DNA; chloroplast dynamics; chloroplast maintenance; plant mitochondrial DNA; plant mitochondrial dynamics; plant organelle inheritance; plant organelle nucleoids; proplastids
  2. Mol Plant. 2019 Aug 29. pii: S1674-2052(19)30287-4. [Epub ahead of print]
      Bird predation during seed maturation causes great loss to agricultural production. In this study, by GWAS analysis of a large-scale sorghum germplasm diversity panel we identified Tannin1, which encodes a WD40 protein functioning in the WD40/MYB/bHLH complex, controls bird feeding behavior in sorghum. Metabolism analysis showed that the accessions of the bird-preference group with mutated tan1-a/b alleles accumulated significantly lower levels of anthocyanins and condensed tannin compounds. Moreover, a variety of aromatic and fatty acid-derived volatiles accumulated at significantly higher levels in the same bird-preference accessions. We subsequently conducted both sparrow-feeding and sparrow volatile attractant assays which confirmed, respectively, the antifeedant and attractant functions of these differentially accumulated metabolites. In addition, the connection between two pathways was demonstrated by discovering that Tannin1 complex modulates fatty acid biosynthesis thus affecting the accumulation of fatty acid-derived volatiles through regulating the expression of SbGL2 gene in sorghum. Taken together, our study identified Tannin1 as the gene underlying the major locus controlling bird feeding behavior in sorghum, illustrating an example of the identification of an ecologically impactful molecular mechanism from the field observation and providing significant insights into the chemistry of bird-plant ecological interactions.
    Keywords:  Bird damage; GWAS; Metabolism; Tannin; Volatiles