bims-plasge Biomed News
on Plastid Genes
Issue of 2018‒06‒17
two papers selected by
Vera S. Bogdanova
Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences

  1. Mol Plant. 2018 Jun 06. pii: S1674-2052(18)30187-4. [Epub ahead of print]
      Mandarin (Citrus reticulata) is one of the most important citrus crops worldwide. Its domestication is believed to occur in South China, which has been one of the cultivation centers for four millennia. We collected natural wild populations of mandarin around the Nanling region and cultivated landraces in the vicinity. The citric acid level was dramatically reduced in cultivated mandarins. To understand the genetic basis of mandarin domestication, we de novo assembled a draft genome of wild mandarin and analyzed a set of 104 citrus genomes. The results showed that the Mangshan mandarin is a primitive type and that two independent domestication events have occurred, resulting in two groups of cultivated mandarins (MD1 and MD2) in the North and South of the Nanling Mountains, respectively. Two bottlenecks and two expansions of effective population size were identified for the MD1 group of cultivated mandarins. However, in the MD2 group, there was a long and continuous decrease in the population size. MD1 and MD2 mandarins showed different patterns of interspecific introgression from cultivated pummelo species. We identified a genomic region of high divergence in an aconitate hydratase (ACO) gene involved in the regulation of citrate content, which was possibly under selection during the domestication of mandarin. This study provides concrete genetic evidence for the geographical origin of extant wild mandarin populations and sheds light on the domestication and evolutionary history of mandarin.
  2. Plant Physiol Biochem. 2018 May 31. pii: S0981-9428(18)30249-3. [Epub ahead of print]129 168-179
      Among the different abiotic stresses, salt stress has a significant effect on the growth and yield of grapevine (Vitis vinifera L.). In this study, we employed RNA sequence based transcriptome analysis to study salinity stress response in grape variety Thompson Seedless. Salt stress adversely affected the growth related and physiological parameters and the effect on physiological parameters was significant within 10 days of stress imposition. A total of 343 genes were differentially expressed in response to salt stress. Among the differentially expressed genes (DEGs) only 42 genes were common at early and late stages of stress. The gene enrichment analysis revealed that GO terms related to transcription factors were over-represented. Among the DEGs, 52 were transcription factors belonging to WRKY, EREB, MYB, NAC and bHLH families. Salt stress significantly affected several pathways like metabolic pathways, biosynthesis of secondary metabolites, membrane transport development related pathways etc. 343 DEGs were distributed on all the 19 chromosomes, however clustered regions of DEGs were present on chromosomes 2, 5, 6 and 12 suggesting probable QTLs for imparting tolerance to salt and other abiotic stresses. Real-time PCR of selected genes in control and treated samples of grafted and own root vines demonstrated that rootstock influenced expression of salt stress responsive genes. Microsatellite regions were identified in ten selected salt responsive genes and highly polymorphic markers were identified using fifteen grape genotypes. This information will be useful for the identification of key genes involved in salt stress tolerance in grape. The identified DEGs could also be useful for genome wide analysis for the identification of polymorphic markers for their subsequent use in molecular breeding for developing salt tolerant grape genotypes.
    Keywords:  Abiotic stress; Grapes; Polymorphic markers; RNA-Seq; Rootstock effect; Salinity