A telosma mosaic virus-based vector for foreign gene expression and virus-induced gene silencing in the perennial woody vine, passion fruit (Passiflora edulis)

Passion fruit (Passiflora edulis) is a perennial, woody, tropical vine crop. It produces edible round to oval fruit that has been increasingly favored for its unique aroma and taste, and richness in antioxidants, vitamins and minerals. However, the functional genomic study of passion fruit lags far behind due to a lack of simple and efficient genetic tools. Here, we report the development of virus-mediated protein overexpression (VOX) and virus-induced gene silencing (VIGS) vector based on telosma mosaic virus (TelMV), an emerging potyvirus infecting passion fruit plants worldwide. This vector, designated pTelMV-GW, incorporates the Gateway-compatible recombination sites for rapid gene cloning. We show that this vector allows for the systemic stable expression of two heterologous proteins, green fluorescent protein (GFP) and bacterial phytoene synthase (crtB) in passion fruit plants, and pTelMV-GW containing different fragments of GFP can also induce systemic gene silencing on the GFP-transgenic N. benthamiana plants. Moreover, we demonstrated that in passion fruit plants, this vector can trigger gene silencing of endogenous phytoene desaturase (PDS) to a limited extent. Furthermore, we upgraded the vector by using a mild TelMV strain that does not induce noticeable symptoms in plants. We show that the upgraded vector (pTelMV-R181K-GW) containing PDS or ChlI fragments induces the robust silencing of the corresponding endogenous gene in passion fruit plants. Together, we reported the first development of VIGS and VOX vectors in passion fruit plants, as the first step in our endeavor to discover horticulturally important genes for improving passion fruit production and quality.