Optimization of Virus-induced Gene Silencing to Facilitate Evo-devo Studies in the Emerging Model Species Mimulus guttatus (Phrymaceae)1

Abstract Mimulus guttatus DC. (yellow monkey-flower; Phrymaceae) is an important model species for ecological and evolutionary studies, being locally adapted to a wide range of elevation, moisture and temperature gradients, soil types, and pollinator availabilities. In order to advance this species as a model for evolutionary genetic studies, we have developed virus-induced gene silencing (VIGS) using the tobacco rattle virus (TRV) to assay gene function. We demonstrate the effectiveness of Agrobacterium-mediated VIGS in two divergent populations of M. guttatus, Iron Mountain 767 (IM767) and Point Reyes (PR). Plants infected with a fragment of the carotenoid biosynthesis pathway gene PHYTOENE DESATURASE (PDS) cloned into the TRV2 vector exhibited endogenous PDS silencing and photobleached phenotypes. We further assayed for VIGS-induced floral phenotypes by silencing paralogous genes putatively affecting floral symmetry, CYCLOIDEA1 (CYC1) and CYCLOIDEA2 (CYC2). Simultaneous silencing of CYC1 and CYC2 resul...