Polysaccharide Peptide Treatment Eliminates Strawberry Viruses and Promotes Strawberry Plant Growth and Rooting in Tissue Culture Media

Based on our previous finding that polysaccharide peptide (PSP) has substantial antiviral activity, we cultured strawberry plants infected with strawberry mild yellow edge virus (SMYEV) or strawberry vein banding virus (SVBV) in Murashige and Skoog (MS) media supplemented with PSP to test its ability to eliminate these viruses. PSP not only improved the elimination of SMYEV and SVBV but also promoted the growth and rooting of strawberry plants in tissue culture. On the 45th day, the average height of the ‘Ningyu’ strawberry plants in the 1-mg/ml PSP treatment group was 1.91 cm, whereas that of the plants in the control group was 1.51 cm. After the same time point, the number of new leaves on the tissue culture media supplemented with 1 mg/ml and 500 μg/ml of PSP and without PSP were 4.92, 4.41, and 3.53, respectively. PSP also promoted strawberry rooting and significantly increased both the length and number of roots. In addition, after treatment with the 1-mg/ml PSP treatment in tissue culture for 45 days followed by meristem-shoot-tip culture, the elimination rates of SMYEV and SVBV in regenerated ‘Ningyu’ strawberry plants ranged from 60 to 100%. This study investigated the use of the antiviral agent PSP for virus elimination. PSP has a low production cost and thus has great application potential for virus elimination in crop plants.