Engineering synthetic genetic circuits to reprogram plant root growth

Synthetic control over spatial patterns of gene expression in plant root tissues can be used to “reprogram” individual aspects of their root growth, according to a new study. “Ultimately, methods for programming novel traits in plants will become increasingly useful as climate challenges grow and new agricultural solutions are needed,” write the authors. The ability to engineer genetic circuits that can modulate gene expression patterns and drive the development of specific traits has been a longstanding goal of synthetic biology. In plants, for example, this approach could be used to alter root system growth in a predictable way and influence roots’ ability to reach essential soil nutrients and acquire water during drought. One approach toward this goal is using synthetic genetic circuits – engineered networks of genes linked through transcriptional and post-transcriptional regulation. While synthetic gene circuits have been implemented in various prokaryotic and eukaryotic cell lines, the technology has been difficult to implement in plants due to the time required for producing transgenic lines and the difficulty of tuning circuit activity across diverse cell types. Jennifer Brophy and colleagues created a collection of synthetic transcriptional regulators and used the elements to control gene expression across root tissues in the Arabidopsis plant. Brophy et al. show that the approach could be used to reprogram plant’s root development and predictably alter lateral root density, without affecting other aspects of normal plant growth. “The lessons learned by Brophy et al. are key to the future success of implementing and translating combinatorial circuits not just into plants but more broadly into other complex biological systems,” write Simon Alamos and Patrick Shih in a related Perspective. “This effort constitutes a milestone in the genetic engineering of a whole, fully developed multicellular organism and points to the challenges ahead.”