Pararetroviruses, diseases, integration and genomes


PARADIGM is a programme in the EU framework V coordinated by Marie-Line Caruana and Pierre-Yves Teycheney of the Centre International de Recherche Agronomique pour le Développement (CIRAD), France, and involves seven partners from France, UK, Austria, Switzerland and Spain. (Project QLTR 2001-02098 duration: October 2002 – April 2006)  

Link to Leicester Work in Pararetroviruses

Links on this page: Endogenous Pararetroviruses - Objectives - Workplan - Contact


Endogenous pararetroviruses

Numerous endogenous pararetroviruses (EPRVs) are now known to be integrated in variable copy numbers into the genome of various crops such as banana, petunia and tobacco. Although EPRVs might in some cases be simply neutral components of plant genomes, in other instances they can be infectious, express viral particles and cause severe diseases in plants. Recent experimental evidences show that EPRVs are widespread in the genome of a large number of crops and might be highly detrimental to existing and future crop improvement-oriented breeding programmes, in vitro mass propagation of vegetative crops and germplasm conservation. Our project aims at studying the biodiversity and roles of EPRVs in plant germplasms, their interactions with plant and viral genomes, the associated risks in pathogenesis, and their potential to confer viral resistance in order to develop appropriate risk assessment strategies for the control of potentially pathogenic EPRV sequences in crops relevant to European agriculture.


Overall objectives of the PARADIGM consortium

The research that is carried out by the consortium will be primarily based on existing experimental models (banana, tobacco, petunia) for the development of risk assessment strategies, then applied to crops relevant to European agriculture for the implementation stage. The consortium will share and apply their acknowledged complementary expertise and experience to develop experimental approaches with the specific objectives of:

  • Investigating the biodiversity and evolutionary status of EPRVs in such crops;
  • Screening economically important crops to European agriculture for possibly deleterious EPRVs;
  • Evaluating the risks of EPRVs for germplasm conservation and for ongoing and future breeding programmes, including those aimed at creating genetically modified crops;
  • Determining the mechanisms of (i) integration of EPRVs in plant genomes and (ii) those of activation, excision and expression of EPRVs leading to infectious episomal viral genomes;
  • Defining the effect of EPRVs on plant genomes stability and dynamics;
  • Characterizing the mechanisms developed by plants to control EPRVs, such as gene silencing, and the strategies developed by pararetroviruses to suppress such controls;
  • Devising risk assessment and control strategies for EPRVs, and implementing such strategies through industrial partnerships with European plant biotech and plant breeding

Workpackages in Paradigm

The project has been divided into 4 scientific workpackages aimed at answering clearly defined questions:

WPI: What is the exact extent and biodiversity of EPRVs within plant germplasms? Coordination in Leicester.

WPII: What are the mechanisms of movement of viral sequences into and out of the plant genomes?

WPIII: What are the interactions between EPRVs and plant genomes?

WPIV: What is the role of, and risk related to, EPRVs in pathogenesis?



Trude Schwarzacher on +44/0 116 252 2276, email TS32(a), web page