Molecular and Ultrastructural Mechanisms Underlying Yellow Dwarf Symptom Formation in Wheat after Infection of Barley Yellow Dwarf Virus

Int J Mol Sci. 2018 Apr 13;19(4):1187. doi: 10.3390/ijms19041187.

Abstract

Wheat (Tritium aestivum L.) production is essential for global food security. Infection of barley yellow dwarf virus-GAV (BYDV-GAV) results in wheat showing leaf yellowing and plant dwarfism symptom. To explore the molecular and ultrastructural mechanisms underlying yellow dwarf symptom formation in BYDV-GAV-infected wheat, we investigated the chloroplast ultrastructure via transmission electron microscopy (TEM), examined the contents of the virus, H₂O₂, and chlorophyll in Zhong8601, and studied the comparative transcriptome through microarray analyses in the susceptible wheat line Zhong8601 after virus infection. TEM images indicated that chloroplasts in BYDV-GAV-infected Zhong8601 leaf cells were fragmentized. Where thylakoids were not well developed, starch granules and plastoglobules were rare. Compared with mock-inoculated Zhong8601, chlorophyll content was markedly reduced, but the virus and H₂O₂ contents were significantly higher in BYDV-GAV-infected Zhong8601. The transcriptomic analyses revealed that chlorophyll biosynthesis and chloroplast related transcripts, encoding chlorophyll a/b binding protein, glucose-6-phosphate/phosphate translocator 2, and glutamyl-tRNA reductase 1, were down-regulated in BYDV-GAV-infected Zhong8601. Some phytohormone signaling-related transcripts, including abscisic acid (ABA) signaling factors (phospholipase D alpha 1 and calcineurin B-like protein 9) and nine ethylene response factors, were up-regulated. Additionally, reactive oxygen species (ROS)-related genes were transcriptionally regulated in BYDV-GAV infected Zhong8601, including three up-regulated transcripts encoding germin-like proteins (promoting ROS accumulation) and four down-regulated transcripts encoding peroxides (scavenging ROS). These results clearly suggest that the yellow dwarf symptom formation is mainly attributed to reduced chlorophyll content and fragmentized chloroplasts caused by down-regulation of the chlorophyll and chloroplast biosynthesis related genes, ROS excessive accumulation, and precisely transcriptional regulation of the above-mentioned ABA and ethylene signaling- and ROS-related genes in susceptible wheat infected by BYDV-GAV.

Keywords: Tritium aestivum L., barley yellow dwarf virus; abscisic acid; chlorophyll; chloroplast; ethylene; reactive oxygen species; yellow dwarf symptom formation.

Publication types

  • Comparative Study

MeSH terms

  • Chlorophyll / analysis
  • Chloroplasts / pathology
  • Chloroplasts / ultrastructure*
  • Chloroplasts / virology
  • Cloning, Molecular
  • Gene Expression Profiling / methods*
  • Gene Regulatory Networks / drug effects
  • Luteovirus / pathogenicity*
  • Microscopy, Electron, Transmission
  • Oligonucleotide Array Sequence Analysis / methods
  • Plant Diseases / virology*
  • Plant Proteins / genetics
  • Triticum / chemistry*
  • Triticum / cytology
  • Triticum / growth & development
  • Triticum / virology
  • Viral Load
  • Water / analysis

Substances

  • Plant Proteins
  • Water
  • Chlorophyll