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Summary: Synthetic biology has the potential to revolutionize biotechnology, public health, and agriculture. Recent studies have shown the enormous potential of plants as chassis for synthetic biology applications. However, tools to precisely manipulate metabolic pathways for bioproduction in plants are still needed.We used bacterial allosteric transcription factors (aTFs) that control gene expression in a ligand‐specific manner and tested their ability to repress semi‐synthetic promoters in plants. We also tested the modulation of their repression activity in response to specific plant metabolites, especially phenylpropanoid‐related molecules. Using these aTFs, we also designed synthetic genetic circuits capable of computing Boolean logic operations.Three aTFs, CouR, FapR, and TtgR, achieved c. 95% repression of their respective target promoters. For TtgR, a sixfold de‐repression could be triggered by inducing its ligand accumulation, showing its use as biosensor. Moreover, we designed synthetic genetic circuits that use AND, NAND, IMPLY, and NIMPLY Boolean logic operations and integrate metabolite levels as input to the circuit.We showed that biosensors can be implemented in plants to detect phenylpropanoid‐related metabolites and activate a genetic circuit that follows a predefined logic, demonstrating their potential as tools for exerting control over plant metabolic pathways and facilitating the bioproduction of natural products. [ABSTRACT FROM AUTHOR]

Keywords: CRISPR/Cas9; crop improvement; gene editing; miRNA; post-transcription EN CRISPR/Cas9 crop improvement gene editing miRNA post-transcription 2208 2212 5 04/11/23 20230409 NES 230409 B Gene editing tools such as CRISPR/Cas9 are often thought of as a means to prevent gene expression; however, a more subtle and yet powerful approach is the enhancement of gene expression by precise deletion of repressor sites within a gene of interest. For example, preassembled CRISPR/Cas RNPs using the Cas9 protein have been delivered using particle bombardment into maize and wheat embryos, and plants have been regenerated without the addition of exogenous genes (including no selection marker), resulting in on-target editing frequencies above 2% ([18]; [11]). As the CRISPR/Cas technology matures, gene editing will become more precise and predictable, for example with tools such as APOBEC-Cas9 ([20]), and hence broadening the miRNA regulatory networks amenable to gene editing. [Extracted from the article]

Plants respond to biotic stressors by modulating various processes in an attempt to limit the attack by a pathogen or herbivore. Triggering these different defense processes requires orchestration of a network of proteins and RNA molecules that includes microRNAs (miRNAs). These short RNA molecules (20-22 nucleotides) have been shown to be important players in the early responses of plants to stresses because they can rapidly regulate the expression levels of a network of downstream genes. The ascomycete Fusarium graminearum is an important fungal pathogen that causes significant losses in cereal crops worldwide. Using the well-characterized Fusarium-Arabidopsis pathosystem, we investigated how plants change expression of their miRNAs globally during the early stages of infection by F. graminearum . In addition to miRNAs that have been previously implicated in stress responses, we have also identified evolutionarily young miRNAs whose levels change significantly in response to fungal infection. Some of these young miRNAs have homologs present in cereals. Thus, manipulating expression of these miRNAs may provide a unique path toward development of plants with increased resistance to fungal pathogens., Competing Interests: Competing Interests The authors declare no competing interests.