Synthetic strategies for plant signalling studies: molecular toolbox and orthogonal platforms

Abstract

SUMMARYPlants deploy a wide array of signalling networks integrating environmental cues with growth, defence and developmental responses. The high level of complexity, redundancy and connection between several pathways hampers a comprehensive understanding of involved functional and regulatory mechanisms. The implementation of synthetic biology approaches is revolutionizing experimental biology in prokaryotes, yeasts and animal systems and can likewise contribute to a new era in plant biology. This review gives an overview on synthetic biology approaches for the development and implementation of synthetic molecular tools and techniques to interrogate, understand and control signalling events in plants, ranging from strategies for the targeted manipulation of plant genomes up to the spatiotemporally resolved control of gene expression using optogenetic approaches. We also describe strategies based on the partial reconstruction of signalling pathways in orthogonal platforms, like yeast, animal and in vitro systems. This allows a targeted analysis of individual signalling hubs devoid of interconnectivity with endogenous interacting components. Implementation of the interdisciplinary synthetic biology tools and strategies is not exempt of challenges and hardships but simultaneously most rewarding in terms of the advances in basic and applied research. As witnessed in other areas, these original theoretical-experimental avenues will lead to a breakthrough in the ability to study and comprehend plant signalling networks.

Reconstitution of the plant ubiquitination cascade in bacteria using a synthetic biology approach

“…The signaling pathways in higher plants are intertwined and constitute signaling networks with a high degree of complexity, which poses a challenge for the analysis of individual signaling pathways or biochemical cascades as a whole (Jacobo‐Velázquez et al ., ; Benning and Sweetlove, ; Braguy and Zurbriggen, ). For example, there are many de‐ubiquitinating enzymes in plant cells functioning to eliminate ubiquitination modification, which might impede the biochemical characterization of ubiquitinated proteins (Yan et al ., ).…”

“…For example, there are many de‐ubiquitinating enzymes in plant cells functioning to eliminate ubiquitination modification, which might impede the biochemical characterization of ubiquitinated proteins (Yan et al ., ). Synthetic biology applies basic engineering principles to construct synthetic biological modules and systems for both basic and applied research, thus allowing the reconstitution of the signaling cascades or biochemical pathways in lower organisms or in completely heterologous systems to avoid interference from the signaling or biochemical networks (Benning and Sweetlove, ; Braguy and Zurbriggen, ). Escherichia coli is a well‐characterized prokaryotic host, and a wide array of metabolic pathways for production of plant‐derived secondary metabolites, such as paclitaxel, artemisinin, reticuline and phenylpropanoids, have been reconstituted in this bacterial system (O'Connor, ).…”

Identification of critical cysteine sites in brassinosteroid‐insensitive 1 and novel signaling regulators using a transient expression system

“…Synthetic biology applies the concepts of modularity and orthogonality, allowing reconstruction of biological pathways in a heterologous system (Jacobo-Vel azquez et al, 2015;Braguy & Zurbriggen, 2016). For reconstruction of the plant signaling pathways, the mammalian cell system provides a popular orthogonal platform.…”

“…For reconstruction of the plant signaling pathways, the mammalian cell system provides a popular orthogonal platform. However, the high degree of orthogonality could also become a disadvantage in reconstructing those complex signaling pathways, which requires the addition of plenty of signaling components (Jacobo-Vel azquez et al, 2015;Braguy & Zurbriggen, 2016). As for BR signaling, PP2A, which dephosphorylates BZR1 and BES1, may represent an obstacle to reconstructing the BR signaling in mammalian cells or other heterologous systems.…”

Synthetic biology for basic and applied plant research

“…Synthetic Biology offers a new way to explore individual signaling pathways by reassembling them bottom up from modules in non-interfering backgrounds of new chassis. Braguy and Zurbriggen (2016) describe this approach in detail. Ultimately, understanding how signaling pathways feed into programmable plant genetic circuits will be essential for the engineering of plants to be more efficient or to produce novel compounds.…”