bims-plasge Biomed News
on Plastid Genes
Issue of 2018‒05‒20
six papers selected by
Vera S. Bogdanova
Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences

  1. Theor Appl Genet. 2018 May 12.
      KEY MESSAGE: Phosphorus deficiency in soil is a worldwide constraint threatening maize production. Through a genome-wide association study, we identified molecular markers and associated candidate genes and molecular pathways for low-phosphorus stress tolerance. Phosphorus deficiency in soils will severely affect maize (Zea mays L.) growth and development, thus decreasing the final yield. Deciphering the genetic basis of yield-related traits can benefit our understanding of maize tolerance to low-phosphorus stress. However, considering that yield-related traits should be evaluated under field condition with large populations rather than under hydroponic condition at a single-plant level, searching for appropriate field experimental sites and target traits for low-phosphorus stress tolerance is still very challenging. In this study, a genome-wide association analysis using two natural populations was performed to detect candidate genes in response to low-phosphorus stress at two experimental sites representative of different climate and soil types. In total, 259 candidate genes were identified and these candidate genes are mainly involved in four major pathways: transcriptional regulation, reactive oxygen scavenging, hormone regulation, and remodeling of cell wall. Among these candidate genes, 98 showed differential expression by transcriptome data. Based on a haplotype analysis of grain number under phosphorus deficiency condition, the positive haplotypes with favorable alleles across five loci increased grain number by 42% than those without favorable alleles. For further verifying the feasibility of genomic selection for improving maize low-phosphorus tolerance, we also validated the predictive ability of five genomic selection methods and suggested that moderate-density SNPs were sufficient to make accurate predictions for low-phosphorus tolerance traits. All these results will facilitate elucidating genetic basis of maize tolerance to low-phosphorus stress and improving marker-assisted selection efficiency in breeding process.
  2. Funct Integr Genomics. 2018 May 12.
      Sweet potato (Ipomoea batatas (L.) Lam.) is one of the most important root crops in the world. Initial formation and development of storage roots (SRs) are key factors affecting its yields. In order to study the molecular mechanism and regulatory networks of the SRs development process, we have analyzed root transcriptomes between the high and low starch content sweet potato accessions at three different developmental stages. In this study, we assembled 46,840 unigenes using Illumina paired-end sequencing reads and identified differentially expressed genes (DEGs) between two accessions. The numbers of DEGs were increased with the development of SRs, indicating that the difference between two accessions is enlarging with the maturation. DEGs were mainly enriched in starch biosynthesis, plant hormones regulatory, and genetic information processing pathways. Then, expression patterns of DEGs that are most significant and starch biosynthesis related were validated using qRT-PCR. Our results provide valuable resources to future study on molecular mechanisms of SRs development and candidate genes for starch content improvement in sweet potato.
    Keywords:  Gene regulation; RNA-Seq; Starch content; Storage root; Sweet potato
  3. Mol Phylogenet Evol. 2018 May 10. pii: S1055-7903(17)30464-5. [Epub ahead of print]
      Whole chloroplast genome sequence analysis of 58 wild and domesticated rice samples was used to investigate their phylogeny providing more detail on the biogeography of the major groups of wild A genome rices globally. An optimized chloroplast assembly method was developed and applied to extracting high quality whole chloroplast genome sequences from shot gun whole DNA sequencing data. Forty complete high quality chloroplast genome sequences were assembled (including; temperate japonica, tropical japonica and aus). The South American and African wild rice relationships were confirmed, while the Australian chloroplast type was found to extend north to the Philippines. The remainder could be divided into an African (O. barthii and the domesticated O. glaberrima) clade and the Asian taxa. The Asian taxa were placed in two distinct clades including the domesticated O. sativa ssp. indica and O. sativa ssp. japonica respectively. These two groups of wild rices had substantially overlapping distributions with the O. sativa japonica group extending further west into India. The aromatic rices had japonica chloroplasts as expected. A polyphyletic maternal genome origin of the cultivated aus group of rices was suggested by the identification of aus accessions in both the wild indica and japonica clades. The current distribution of the chloroplast types appears to differ significantly to that of the nuclear genome diversity suggesting a complex evolutionary history of the rice progenitors leading to the domestication of rice.
    Keywords:  Asian wild rice; OryzaAA genome; chloroplast sequence; de novo assembly; mapping assembly; phylogenetic analysis
  4. Plant Physiol Biochem. 2018 May 07. pii: S0981-9428(18)30209-2. [Epub ahead of print]
      Genome manipulation technology is one of emerging field which brings real revolution in genetic engineering and biotechnology. Targeted editing of genomes pave path to address a wide range of goals not only to improve quality and productivity of crops but also permit to investigate the fundamental roots of biological systems. These goals includes creation of plants with valued compositional properties and with characters that confer resistance to numerous biotic and abiotic stresses. Numerous novel genome editing systems have been introduced during the past few years; these comprise zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and clustered regularly interspaced short palindromic repeats/Cas9 (CRISPR/Cas9). Genome editing technique is consistent for improving average yield to achieve the growing demands of the world's existing food famine and to launch a feasible and environmentally safe agriculture scheme, to more specific, productive, cost-effective and eco-friendly. These exciting novel methods, concisely reviewed herein, have verified themselves as efficient and reliable tools for the genetic improvement of plants.
    Keywords:  Crop improvement; Genetic innovation; Genome editing; Transcription
  5. FEBS Lett. 2018 May 12.
      In most eukaryotes, cytoplasmic dynein serves as the primary cytoskeletal motor for minus-end-directed processes along microtubules. However, land plants lack dynein, having instead a large number of kinesin-14s, which suggests that kinesin-14s may have evolved to fill the cellular niche left by dynein. In addition, land plants do not have centrosomes, but contain specialized microtubule-based structures called phragmoplasts that facilitate the formation of new cell walls following cell division. This Review aims to compile the evidence for functional diversification of kinesin-14s in land plants. Known functions include spindle morphogenesis, microtubule-based trafficking, nuclear migration, chloroplast distribution, and phragmoplast expansion. Plant kinesin-14s have also evolved direct roles in chromosome segregation in maize and novel biochemical features such as actin transport and processive motility in the homodimeric state. This article is protected by copyright. All rights reserved.
  6. Gene. 2018 May 10. pii: S0378-1119(18)30510-9. [Epub ahead of print]
      Long non coding RNAs (lncRNAs) are a class of non-protein coding RNAs that play a crucial role in most of the biological activities like nodule metabolism, flowering time and male sterility. Quite often, the function of lncRNAs is species-specific in nature. Thus an attempt has been made in cluster bean (Cyamopsis tetragonoloba) for the first time to computationally identify lncRNAs based on a proposed index and study their targeted genes. Further, these targeted genes of lncRNAs were identified and characterized for their role in various biological processes like stress mechanisms, DNA damage repair, cell wall synthesis. Besides, lncRNAs and miRNAs bearing Simple Sequence Repeats (SSRs) were identified that contribute towards biogenesis of small non-coding RNAs. Moreover, five novel endogenous Target Mimic lncRNAs (eTMs) were identified that may disrupt the miRNA-mRNA regulations. For easy understanding and usability, a database CbLncRNAdb has been developed and made available at
    Keywords:  Cluster bean; Endogenous target mimic; Long non coding RNAs; Micro RNA; Principal component analysis