Unraveling the roles of plant specialized metabolites: using synthetic biology to design molecular biosensors

Abstract

Plants are a rich source of specialized metabolites with a broad range of bioactivities and many applications in human daily life. Over the past decades significant progress has been made in identifying many such metabolites in different plant species and in elucidating their biosynthetic pathways. However, the biological roles of plant specialized metabolites remain elusive and proposed functions lack an identified underlying molecular mechanism. Understanding the roles of specialized metabolites frequently is hampered by their dynamic production and their specific spatiotemporal accumulation within plant tissues and organs throughout a plant's life cycle. In this review, we propose the employment of strategies from the field of Synthetic Biology to construct and optimize genetically encoded biosensors that can detect individual specialized metabolites in a standardized and high-throughput manner. This will help determine the precise localization of specialized metabolites at the tissue and single-cell levels. Such information will be useful in developing complete system-level models of specialized plant metabolism, which ultimately will demonstrate how the biosynthesis of specialized metabolites is integrated with the core processes of plant growth and development.

Metal–Organic Framework-Based Biosensor for Detecting Hydrogen Peroxide in Plants through Color-to-Thermal Signal Conversion

“…The LODs of leaf, petiole, and root sensors were determined to be 600, 800, and 900 nM, respectively. A sensor’s specificity was further evaluated with various stress-related plant metabolites . As plants’ main photosynthetic products and nutrients, glucose (Glu) and sucrose (Suc) play a critical role in plant growth, development, stress, and metabolism.…”

“…A sensor's specificity was further evaluated with various stressrelated plant metabolites. 59 As plants' main photosynthetic products and nutrients, glucose (Glu) and sucrose (Suc) play a critical role in plant growth, development, stress, and metabolism. In most cases, Glu and Suc act as nutrient signals to regulate plant growth and development.…”

Enhancement of Phytosterol and Triterpenoid Production in Plant Hairy Root Cultures—Simultaneous Stimulation or Competition?

“…Specialized metabolites have numerous applications for humans in many branches of the industry but their biological roles in plants remains elusive, and proposed functions lack an identified underlying molecular mechanism. Understanding the function of specialized metabolites can be hampered by their specific spatiotemporal biosynthesis and accumulation within plant tissues and organs throughout the cycle of plant growth and development [ 39 ]. One such group of compounds embracing a variety of compounds with diverse but not always clearly defined functions, classified either as general or specialized metabolites and thus potentially competing, are terpenoids.…”

Plant Biology Research: What Is Next?

“…For one, to see if we can recreate the native behavior to ensure that we fully understand the pathway or the mechanism of regulation. In addition, this can be a useful endeavor from a practical perspective, as is the case in metabolic engineering, where a native or semi-synthetic biosynthetic pathway is expressed in a heterologous host (an intact plant or a cell suspension) to produce a valuable metabolite (Lu et al, 2016 ; Birchfield and McIntosh, 2020 ), or in biosensing, where a synthetic genetic construct is introduced to turn the host into a bio-detector for a particular stimulus or ligand of interest, e.g., a metabolite (Garagounis et al, 2021 ).…”