Establishment of a Virus-Induced Gene-Silencing (VIGS) System in Passiflora edulis Sims and Its Use in the Functional Analysis of PechlH

Abstract

Passion fruit is a very important tropical and subtropical fruit that not only has a good edible flavour, but also has high ornamental value. However, the functions of important trait genes in passion fruit have been difficult to elucidate due to the difficulty of stable genetic transmission in passion fruit. The VIGS system for the tobacco rattle virus (TRV) has been widely used in a number of crops, but no success has been reported in passion fruit. In this study, we used the PePDS marker gene to unravel the passion fruit VIGS system. The use of albino phenotype observation and quantitative PCR to detect gene expression showed that the PDS albino phenotype was successfully induced in the young leaves of passion fruit seedlings after 7 days, while a significant down-regulation of expression occurred in the phenotypic plants. The albino phenotype can be maintained for 14–16 d. In addition, we chose the chlorophyll-synthesis-related gene PechlH for the VIGS silencing of passion fruit leaves. When the PechlH gene was knocked out, the leaves of the passion fruit lost their green colour and showed yellowing symptoms. This revealed that the PechlH gene was involved in the chloroplast synthesis pathway. Finally, using different OD600 gradients in PePDS, we demonstrated that the silencing efficiency reached 46.70% at an OD600 of 0.8. Thus, an effective and stable VIGS system was achieved in passion fruit. This will help to accelerate the study of gene function in passion fruit in the future.