A telosma mosaic virus-based vector for foreign gene expression and virus-induced gene silencing in passion fruit

Passion fruit (Passiflora edulis) is a perennial, woody, tropical vine. It produces edible round to oval fruit that is highly favored for its unique aroma and taste, as well as its richness in antioxidants, vitamins, and minerals. However, functional genomics studies of passion fruit are scarce, as simple and efficient genetic tools are lacking for this species. Here, we developed virus-mediated protein overexpression (VOX) and virus-induced gene silencing (VIGS) vectors based on the telosma mosaic virus (TelMV), an emerging potyvirus that infects passion fruit plants worldwide. This vector, designated pTelMV-GW, incorporates Gateway-compatible recombination sites for rapid gene cloning. Using this vector, we achieved systemic stable expression of 2 heterologous proteins in passion fruit: green fluorescent protein (GFP) and bacterial phytoene synthase (CrtB). Additionally, pTelMV-GW containing different GFP fragments also induced systemic gene silencing in GFP-transgenic Nicotiana benthamiana plants. Furthermore, we used this vector to trigger phytoene desaturase (PDS) and magnesium chelatase subunit I (ChlI) silencing in passion fruit plants. The TelMV-based VIGS was enhanced using a mild TelMV strain encoding a mutated helper-component proteinase (HC-Pro) with impaired RNA silencing suppressor activity. This upgraded vector (pTelMV-R181K-GW), containing PDS or ChlI fragments, induced clear photobleaching or yellowing phenotypes in passion fruit plants. Overall, our work presents a set of VIGS and VOX vectors for use in passion fruit plants, a crucial step towards identifying horticulturally important genes for improving passion fruit production and quality.