Vegetos

Abstract

Virus-induced gene silencing (VIGS) has not yet successfully been used as a tool for gene functional analysis in non grass monocotyledonous geophytes. We therefore tested VIGS in gladiolus (Gladiolus grandiflora L) using a Tobacco Rattle Virus (TRV) vector containing a fragment of the gladiolus gene encoding phytoene desaturase (PDS). Gladiolus corms and plants were infiltrated with cultures of Agrobacterium tumefasciens transformed with the vector system. We tested the effect of different inoculum concentrations, different inoculation strategies and different growing temperatures after inoculation. Successful gene silencing was obtained by syringe inoculation of the sprouted corms) with Agrobacterium at an OD₆₀₀ of 2 using syringe infiltration of the young bud, and growing the plants at 18°C after inoculation. White streaks characteristic of silencing PDS were first observed four weeks after inoculation and symptoms continued to develop up to eight weeks after inoculation. Silencing was not observed in plants grown at other temperatures, inoculated with lower concentrations of Agrobacterium, or inoculated by other means (corm, leaf, or vacuum infiltration). This is the first report on the potential use of TRV based VIGS in gladiolus and this optimised procedure of the TRV induced gene silencing should further facilitate for highly efficient functional analysis of genes.