Disruption of Chloroplast Function Through Downregulation of Phytoene Desaturase Enhances the Systemic Accumulation of an Aphid-Borne, Phloem-Restricted Virus

Mol Plant Microbe Interact. 2018 Oct;31(10):1095-1110. doi: 10.1094/MPMI-03-18-0057-R. Epub 2018 Aug 27.

Abstract

Chloroplasts play a central role in pathogen defense in plants. However, most studies explaining the relationship between pathogens and chloroplasts have focused on pathogens that infect mesophyll cells. In contrast, the family Luteoviridae includes RNA viruses that replicate and traffic exclusively in the phloem. Recently, our lab has shown that Potato leafroll virus (PLRV), the type species in the genus Polerovirus, forms an extensive interaction network with chloroplast-localized proteins that is partially dependent on the PLRV capsid readthrough domain (RTD). In this study, we used virus-induced gene silencing to disrupt chloroplast function and assess the effects on PLRV accumulation in two host species. Silencing of phytoene desaturase (PDS), a key enzyme in carotenoid, chlorophyll, and gibberellic acid (GA) biosynthesis, resulted in a substantial increase in the systemic accumulation of PLRV. This increased accumulation was attenuated when plants were infected with a viral mutant that does not express the RTD. Application of GA partially suppressed the increase in virus accumulation in PDS-silenced plants, suggesting that GA signaling also plays a role in limiting PLRV infection. In addition, the fecundity of the aphid vector of PLRV was increased when fed on PDS-silenced plants relative to PLRV-infected plants.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Aphids / virology*
  • Chloroplasts / enzymology*
  • Down-Regulation
  • Gene Expression Regulation, Enzymologic
  • Gene Expression Regulation, Plant
  • Gene Silencing
  • Insect Vectors
  • Luteoviridae
  • Nicotiana / metabolism
  • Nicotiana / virology*
  • Oxidoreductases / genetics
  • Oxidoreductases / metabolism*
  • Phloem / virology*

Substances

  • Oxidoreductases
  • phytoene dehydrogenase