Expression of a multigene mushroom luciferin biosynthesis pathway as a pseudo-polycistron in plants

Summary

Researchers attempted to create glowing tomato plants by introducing genes from bioluminescent mushrooms that produce their own light substrate. While the genes worked when temporarily expressed in tobacco plants, stable transgenic tomatoes could not maintain luciferin production. The main challenge was that the light-producing molecule breaks down too quickly in plant tissue, making it difficult to maintain the glow effect.

Background

Bioluminescence has not naturally evolved in higher plants, but transgenic approaches using luciferase reporter genes require exogenous luciferin substrate addition. The mushroom luciferin biosynthesis pathway offers potential for endogenous substrate production by utilizing plant cell wall precursors, providing a logical system for in vivo luciferin generation.

Objective

To develop transgenic plants expressing the mushroom luciferin biosynthesis pathway genes separated from the luciferase reporter, enabling complementation-based bioluminescence assays. The study aimed to create a LBS+ plant phenotype capable of producing luciferin substrate for use with independently expressed luciferase.

Results

Transient expression in N. benthamiana successfully produced bioluminescence when luciferin biosynthesis genes were co-expressed with luciferase. However, transgenic tomato lines failed to produce detectable luciferin in segregated generations despite initial T0 indications. Studies revealed rapid luciferin substrate degradation in plant tissue extracts and species-dependent quenching effects, with tomato displaying near-instantaneous bioluminescence suppression.

Conclusion

While the mushroom luciferin biosynthesis pathway can be functionally expressed in plants transiently, achieving stable transgenic luciferin production faces significant challenges due to substrate instability and plant tissue-mediated quenching. Future improvements require addressing luciferin protection mechanisms and optimizing pathway gene expression levels.
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