Plants with genetically encoded autoluminescence

Abstract

Autoluminescent plants engineered to express a bacterial bioluminescence gene cluster in plastids have not been widely adopted because of low light output. We engineered tobacco plants with a fungal bioluminescence system that converts caffeic acid (present in all plants) into luciferin and report self-sustained luminescence that is visible to the naked eye. Our findings could underpin development of a suite of imaging tools for plants.

Figure 1. Features of the fungal bioluminescence system.

a. Spectrum of fungal bioluminescence (Neonothopanus nambi, in green) overlaid onto the absorbance spectrum of plant leaves (Nicotiana tabacum, in dark gray). b. The caffeic acid cycle shares metabolites with some of the major plant biosynthetic pathways. The fungal or plant origin of enzymes is indicated with mushroom and plantlet symbols, respectively. Abbreviations: 4CL — 4-coumarate:CoA ligase; C3H — p-coumaric acid 3-hydroxylase; C4H — cinnamic acid 4-hydroxylase; CCOMT — caffeoyl-CoA 3-O-methyltransferase; CCR — cinnamoyl-CoA reductase; CHI — chalcone isomerase; CHS — chalcone synthase; CPH — putative caffeoyl pyruvate hydrolase; H3H — hispidin-3-hydroxylase; HispS — hispidin synthase; Luz — luciferase; PAL — phenylalanine ammonia-lyase. Absorbance spectrum of leave is representative of experiment performed on three leaves. Luminescence spectrum is rendered from dataset published in Ref.

Figure 2. Bioluminescent plants at various stages of development.

a. Light emission from N. tabacum plants at germination (i), vegetative (ii) and flowering (iii) stages; light emission from roots (iv) and cross section of flowers (v). Photos were captured on Sony Alpha ILCE-7M3 (Online Methods). The 110 seedlings depicted on panel (i) are representative of three independent experiments. Images of plants in vegetative (ii, 3 weeks) and flowering (iii, 8 weeks) stages, as well as individual flowers (v) are representative of 100 plants followed from in-vitro to flowering in four separate experiments. The age of plants is stated relative to transfer from in vitro to the greenhouse. The image of roots of an individual plant depicted on panel (iv) is representative of three independent imaging experiments on six plants.