Résumé
Yellow leaf of sugarcane, caused by Sugarcane yellow leaf virus (SCYLV), was first reported in Hawaii and Brazil in the late 1980s, and it has since been reported in more than 30 sugarcane producing locations worldwide. Moderate to severe yield losses have been shown to occur in several sugarcane cultivars in several countries. The virus is propagated by planting infected seed-pieces and by several aphid species. Because disease symptoms are not specific and their appearance is unpredictable, reliable diagnosis mostly relies on molecular techniques (serology, RT-PCR, or real-time PCR) that have been developed since the second half of the 1990s. Because infected plants are very often symptomless, SCYLV was spread all over the world through infected germplasm before diagnostic methods were available. Significant genetic diversity exists within SCYLV, and four genotypes of the virus have been identified so far: BRA for Brazil, CUB for Cuba, PER for Peru, and REU for Réunion Island. BRA and PER genotypes, that are phylogenetically relatively close, cannot be easily distinguished and thus were designated BRA-PER genotype. This latter genotype appears widely distributed, whereas the other ones are restricted to a few countries to date. Additionally, variation in infection capacity and in virulence between SCYLV genotypes has recently been demonstrated. Therefore, there is a risk of propagating new virus genotypes that might be more pathogenic, and sugarcane cultivars must be identified virus-free before being dispatched to other locations, even though SCYLV is considered as largely distributed. Detection tools must be carefully tested towards the different SCYLV genotypes to make sure that all variants of the virus can be detected. Although SCYLV is a sugarcane disease that is very frequently detected in quarantine, it can be efficiently eliminated from infected cultivars using tissue culture techniques such as apical meristem culture. (Texte intégral)