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MicroRNA-guided processing impairs Plum pox virus replication, but the virus readily evolves to escape this silencing

Carmen Simón-Mateo1, Juan Antonio García

  • 1Centro Nacional de Biotecnología-CSIC, Campus Universidad Autónoma de Madrid, Spain.

Journal of Virology
|February 14, 2006
PubMed

Insights

Plum pox virus (PPV) chimeras with microRNA (miRNA) target sites showed reduced infectivity in host plants. Virus infectivity was influenced by miRNA sequence, insertion site, and host plant, with escape mutations observed.

Area of Science:

  • Plant virology
  • Molecular biology
  • RNA silencing mechanisms

Background:

  • MicroRNAs (miRNAs) are key regulators of gene expression through RNA silencing.
  • RNA silencing pathways are increasingly recognized for their role in antiviral defense in plants.
  • Plum pox virus (PPV) is a significant pathogen affecting fruit trees.

Purpose of the Study:

  • To investigate the impact of miRNA target sequences on Plum pox virus (PPV) infectivity.
  • To determine if miRNA-guided RNA silencing can interfere with PPV replication in different host plants.
  • To analyze the mechanisms by which PPV might evade miRNA-mediated antiviral defense.

Main Methods:

  • Construction of PPV chimeras containing functional target sequences for Arabidopsis miRNAs (miR171, miR167, miR159).
  • Infection assays of PPV chimeras in three different host plants.
  • Analysis of viral infectivity and replication in the presence and absence of host miRNA activity.
  • Evaluation of PPV chimera behavior in transgenic plants expressing the P1/HC-Pro silencing suppressor.
  • Sequencing of viral RNA to identify mutations in miRNA target sequences.

Main Results:

  • Several PPV chimeras with miRNA target sequences exhibited significantly impaired infectivity compared to controls.
  • The effect on infectivity varied across different host plants, depending on the specific miRNA sequence and its insertion site within the PPV genome.
  • Infection by PPV chimeras was less affected in transgenic plants expressing the P1/HC-Pro silencing suppressor.
  • PPV chimeras rapidly evolved mutations within the miRNA target sequences, particularly in the 5'-terminal region complementary to the miRNA, to escape RNA silencing.

Conclusions:

  • MicroRNA-guided RNA silencing can negatively impact Plum pox virus infectivity in susceptible host plants.
  • PPV employs strategies, including mutations in target sequences, to overcome miRNA-mediated antiviral defense.
  • The effectiveness of miRNA-mediated antiviral defense against PPV is influenced by host factors and viral genetic elements.

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