Résumé
Sugarcane varietal improvement requires the introduction of vegetative propagation material (cuttings, tissue-cultured plantlets). The continued increase of international and intercontinental trade of plants has led to the enforcement of quarantine measures in many countries before the introduction of vegetatively propagated material because many plant pathogens can be carried and transmitted by them. Visacane is the new name of CIRAD's sugarcane quarantine. It covers three main quarantine procedures: detection of pests and pathogens, elimination of pests and pathogens, and transfer of plant material free of pests and pathogens. Visacane has been devoted to sugarcane quarantining for several decades. Besides phytosanitary constraints, this quarantine structure also takes into account legal constraints and ensures, through appropriate contracts, that plant breeders' intellectual property rights over the transferred material are respected. Visacane can import and export varieties from and to most sugarcane growing countries in the world, ensuring that the material is free from any important pest and disease causing agent. Until recently, the sugarcane quarantine process was aimed at detecting known pathogens harboured by the plant material, and at eliminating these pathogens whenever possible. This process takes into account the pathogens that have been previously described and for which efficient detection tools exist, or have to be developed. However, during the last three decades, several new viruses infecting sugarcane have been discovered, including Sugarcane yellow leaf virus, Sugarcane streak mosaic virus and the virus associated with Ramu stunt. Therefore, it can be assumed that unknown pathogens are still to be discovered in sugarcane, especially if these pathogens do not cause symptoms that can be easily observed. For these reasons, the research team associated with Visacane is setting up a new strategy of diagnostics, the so-called sequence-independent approach which aims at deciphering the genomes of all the viruses that inhabit a particular organism. This metagenomics approach will help to improve our routine quarantine diagnostics.