Genome-edited plants, endowed with climate-smart traits, have been promoted as tools for strengthening resilience against climate change. Successful plant gene editing (GE) requires precise regulation of the GE machinery, a process controlled by the promoters, which drives its transcription through interactions with transcription factors (TFs) and RNA polymerase. While constitutive promoters are extensively used in GE constructs, their limitations highlight the need for alternative approaches. This review emphasizes the promise of tissue/organ specific as well as inducible promoters, which enable targeted GE in a spatiotemporal manner with no effects on other tissues. Advances in synthetic biology have paved the way for the creation of synthetic promoters, offering refined control over gene expression and augmenting the potential of plant GE. The integration of these novel promoters with synthetic systems presents significant opportunities for precise and conditional genome editing. Moreover, the advent of bioinformatic tools and artificial intelligence is revolutionizing the characterization of regulatory elements, enhancing our understanding of their roles in plants. Thus, this review provides novel insights into the strategic use of promoters and promoter editing to enhance the precision, efficiency and specificity of plant GE, setting the stage for innovative crop improvement strategies.
The Green Revolution (GR) has substantially improved cereal crop yields and enhanced adaptation to diverse environmental challenges. However, the molecular and cellular mechanisms involving GR-related genes that regulate drought tolerance in plants remain largely unclear. Here, we reveal that the gibberellin (GA) signalling repressor SLENDER RICE 1 (SLR1) negatively regulates the abundance of the dehydration-responsive protein OsBURP3 to enhance drought tolerance in rice. OsBURP3 facilitates the translocation of Sucrose Synthase 1 (OsSUS1), from the cytosol to the nucleus, thereby decreasing the sucrose content. Mutation of OsBURP3 reduces the nucleus accumulation of OsSUS1 to enhance drought tolerance. SLR1 also competitively associates with OsBURP3 in the nucleus to release OsSUS1 back into the cytosol, resulting in elevated sucrose content. Cytological evidences confirm that sucrose contributes to the fine-tuning of the stomata aperture in rice leaves. Collectively, these findings provide a comprehensive framework for understanding the role of GA in regulating drought tolerance by mediating sucrose metabolism in crops.
Plants produce a large array of natural products which play important roles in flavours, fragrances and medicines. However, some high-value plant intermediate metabolites cannot be directly extracted from plants. The tulip tree (Liriodendron chinense) in the Magnoliaceae family is rich in sesquiterpenes. Upon characterizing the functions of 11 Liriodendron chinense terpene synthases, we discovered that LcTPS3 could produce high yields of (+)-germacrene A, which was shown to be a central scaffold in sesquiterpene biosynthesis. This compound can be completely transformed into β-elemene at high temperature, a broad-spectrum antitumor drug widely used in clinical treatment. By expressing LcTPS3 in a precursor-providing Saccharomyces cerevisiae chassis and with the aid of metabolic engineering, the fermentation yield of (+)-germacrene A has been achieved at 14.71 g/L. Site-directed mutagenesis experiments and molecular dynamics simulations revealed that the A280V suppresses the cyclization of substrate by influencing the conformation of the enzyme-substrate. The Y282L facilitates secondary cyclization to produce α-guaiene by shortening the distance between the catalytic residue Y531 and the substrate. These insights underscore the high plasticity of LcTPS3 and suggest that its targeted engineering could unlock the synthesis of a wider array of valuable sesquiterpenes.
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