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J Exp Bot. 2016 Oct;67(19):5857-5868. Epub 2016 Oct 3.

Changes in the DNA methylation pattern of the host male gametophyte of viroid-infected cucumber plants.

Author information

1
Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Politecnica de Valencia (UPV), CPI, Edificio 8 E, Av. de los Naranjos s/n, 46022 Valencia, Spain.
2
Department of Plant Biology, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, SE-750 07 Uppsala, Sweden.
3
Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Politecnica de Valencia (UPV), CPI, Edificio 8 E, Av. de los Naranjos s/n, 46022 Valencia, Spain ggomez@ibmcp.upv.es.

Abstract

Eukaryotic organisms exposed to adverse conditions are required to show a certain degree of transcriptional plasticity in order to cope successfully with stress. Epigenetic regulation of the genome is a key regulatory mechanism allowing dynamic changes of the transcriptional status of the plant in response to stress. The Hop stunt viroid (HSVd) induces the demethylation of ribosomal RNA (rRNA) in cucumber (Cucumis sativus) leaves, leading to increasing transcription rates of rRNA. In addition to the clear alterations observed in vegetative tissues, HSVd infection is also associated with drastic changes in gametophyte development. To examine the basis of viroid-induced alterations in reproductive tissues, we analysed the cellular and molecular consequences of HSVd infection in the male gametophyte of cucumber plants. Our results indicate that in the pollen grain, accumulation of HSVd RNA induces a decondensation of the generative nucleus that correlates with a dynamic demethylation of repetitive regions in the cucumber genome that include rRNA genes and transposable elements (TEs). We therefore propose that HSVd infection impairs the epigenetic control of rRNA genes and TEs in gametic cells of cucumber, a phenomenon thus far unknown to occur in this reproductive tissue as a consequence of pathogen infection.

KEYWORDS:

Cucumber; epigenetic inheritance; hop stunt viroid; viroid-induced pathogenesis; viroids and DNA methylation.; viroid–plant interactions

PMID:
27697787
PMCID:
PMC5066502
DOI:
10.1093/jxb/erw353
[Indexed for MEDLINE]
Free PMC Article

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