Occurrence of Three Genotypes of Sugarcane Yellow Leaf Virus in a Variety Collection in Mauritius

Sugarcaneyellow leaf virus (SCYLV) is widely distributed in Mauritius, but so far the characterisation of genotypes of the virus has not been determined. RT-PCR primers were used to identify genetic diversity of the virus in a variety collection plot. Total nucleic acids were extracted from leaves of thirteen introduced varieties infected by SCYLV and a two-step RT-PCR was optimised for each of the three genotype-specific primer pairs CUB-F/CUB-R, REU-F/B-REV, and PER-F/PER-R tested. The presence of three SCYLV genotypes namely the BRA-PER, CUB and REU was confirmed in the germplasm collection. Genotype REU was observed in 10 varieties while 4 varieties were infected by genotype BRA-PER. Mixed infection with genotypes CUB and REU was observed in variety Co6304 while Q88 was co-infected by genotypes BRA-PER and REU. PCR fragments of 363 bp (BRA-PER), 452 bp (CUB) and 905 bp (REU) amplified from varieties PR67245, Co6304 and S17 were cloned and sequenced. Blast analysis of these three sequences showed high homologies with the corresponding genotype sequences from GenBank—100% similarity with isolate Taiwl (AJ491144, BRA genotype), and >99% similarity with isolates CUB-YL1 (AM083988) and REU-YL2 (AM072756) respectively. Recent screening of some local commercial cultivars revealed infection by REU and BRA-PER genotypes. Further intensive surveys are being carried out to assess the distribution of the three SCYLV genotypes in sugarcane fields in Mauritius.