Abstract:To explain the application of SYBR GreenⅠreal-time quantitative RT-PCR in the analysis of the viruses amounts, the plant samples were collected from the sweet cherry trees Prunus avium cv. Red Lamp which were infected by Prunus necrotic ringspot virus (PNRSV), Prune dwarf virus (PDV), Cherry virus A (CVA) and Little cherry virus-2 (LChV-2) simultaneously. Relative expression of the virus coat protein gene was determined and selected to estimate the amounts of the virus in different plant tissues. The results showed that all of the four virus genes can be detected in flowers, young leaves, mature leaves and senescent leaves, but the expression levels of the genes among the samples were different. PNRSV-CP and CVA-CP obtained similar expression patterns, which were high in the functionally active plant tissues and low in the senescent tissues. The expression patterns of PDV-CP were similar to that of LChV2-CP, which increased in the young leaves and decreased in the functionally active plant tissues. The expression of PNRSV-CP was obviously higher than the other three virus genes in flowers and mature leaves. Compared to the other three genes, the expression of LChV2-CP were the lowest in all of the tissues. This method is suitable for quantitative analysis of sweet cherry viruses in different tissues.