The Variation of GRSPaV in Different Parts of Shine Muscat Grapevines During Their Phenological Periods

Grapevine rupestris stem pitting associated virus (GRSPaV) is the most common virus causing rugose wood disease. It is mainly transmitted via asexual reproduction. Sensitive detection technology and cultivation of virus-free plants are essential for preventing GRSPaV.

The purpose of this study was to establish a GRSPaV detection system, and to determine the appropriate periods and sites of sample collection for virus detection, so as to provide a reference for virus detection and obtaining virus-free materials.

An RT-qPCR detection method was established using the AugeGreen dye method and primers according to the coat protein gene (CP) region. The detection rate and gene expression of GRSPaV in samples from different parts of Shine Muscat grapevines during various phenological stages were examined.

The RT-qPCR detection method for GRSPaV using GRS q CP1 as primer showed 10 times higher sensitivity than that of RT-PCR method. The detection rates of GRSPaV were 100% during the budbreak, shoot growing period, and florescence, 91.7% during the fruit enlargement stage, 94.4% for mature tendrils, and 100% for mature leaves, mature petioles, and tender shoots. Samples showing negative results were all from the young parts of the plants. The young tendrils at florescence showed the highest level of GRSPaV CP gene expression, followed by the mature leaves at florescence. The expression level in mature leaves was the highest among the parts in the same phenological period from berry expansion to maturity. The expression levels in secondary winter buds at the budbreak stage and the secondary laterals at the shoot growing period were both relatively low.

The detection rate of GRSPaV and the GRSPaV CP gene expression level of Shine Muscat grape varied with the progression of phenological periods. The detection rate was the highest from budbreak to florescence, while which was the lowest at berry maturity period. The GRSPaV CP gene expression level was the highest at florescence. Based on both the detection rate and the expression level factors, it could be concluded that the mature leaves at florescence were suitable as samples for GRSPaV virus detection, and the winter buds from the berry expansion to maturity period and the lateral shoots germinated from these buds was appropriate for obtaining virus-free materials.