Frontiers of torenia research: innovative ornamental traits and study of ecological interaction networks through genetic engineering

Abstract

Advances in research in the past few years on the ornamental plant torenia (Torenia spps.) have made it notable as a model plant on the frontier of genetic engineering aimed at studying ornamental characteristics and pest control in horticultural ecosystems. The remarkable advantage of torenia over other ornamental plant species is the availability of an easy and high-efficiency transformation system for it. Unfortunately, most of the current torenia research is still not very widespread, because this species has not become prominent as an alternative to other successful model plants such as Arabidopsis, snapdragon and petunia. However, nowadays, a more global view using not only a few selected models but also several additional species are required for creating innovative ornamental traits and studying horticultural ecosystems. We therefore introduce and discuss recent research on torenia, the family Scrophulariaceae, for secondary metabolite bioengineering, in which global insights into horticulture, agriculture and ecology have been advanced. Floral traits, in torenia particularly floral color, have been extensively studied by manipulating the flavonoid biosynthetic pathways in flower organs. Plant aroma, including volatile terpenoids, has also been genetically modulated in order to understand the complicated nature of multi-trophic interactions that affect the behavior of predators and pollinators in the ecosystem. Torenia would accordingly be of great use for investigating both the variation in ornamental plants and the infochemical-mediated interactions with arthropods.

Application of the CRISPR/Cas9 system for modification of flower color in Torenia fournieri

“…In this study, we attempted to modify flower colors by genome editing of a flavonoid biosynthetic-related gene using the basic CRISPR/Cas9 system. For this purpose, we used Torenia fournieri , a model plant widely applied for flower research [ 20 ]. We targeted the flavanone 3-hydroxylase ( F3H ) gene, a key enzyme gene in the flavonoid biosynthetic pathway (Additional file 1 : Figure S1), because we had previously determined that an F3H mutation was responsible for the white flower color of a torenia cultivar [ 21 ].…”

Ectopic Expression of PAP1 Leads to Anthocyanin Accumulation and Novel Floral Color in Genetically Engineered Goldenrod (Solidago canadensis L.)

“…Limited gene pools hamper achieving this goal in some species, leaving them with a fixed set of colors, or only one color, as with gypsophila and Solidago . In some instances, manipulating the biosynthetic pathways by introducing enzymes or transcription factors, or even a partial pathway, via genetic engineering, has proven to be successful (Xie et al, 2006; Katsumoto et al, 2007; Ben Zvi et al, 2012; Chandler and Sanchez, 2012; Brugliera et al, 2013; Nishihara et al, 2013; Polturak et al, 2016). However, a prerequisite for genetic engineering is the development of a repeatable transformation and regeneration protocol.…”

African violet (Saintpaulia ionantha H. Wendl.): classical breeding and progress in the application of biotechnological techniques

“…Broadly, the first strategy would be to increase the colour range in a single, very high quality variety, as was done using genetic engineering in torenia (Nishihara et al 2013). The second strategy would be to use genetic engineering for the generation of colours not found in the species, such as a true red (van Schaik and Newlands 1963) or deep yellow.…”