Biology subjects

Geelen, D.

Publications and source records attributed to Geelen, D..

3 recordsLinked to original sources

bioRxiv2023

The selective estrogen receptor modulator clomiphene inhibits sterol biosynthesis in Arabidopsis thaliana

Sterols are produced via complex, multistep biosynthetic pathways involving similar enzymatic conversions in plants, animals and fungi, yielding a variety of sterol metabolites with slightly different chemical properties to exert diverse and specific functions. The role of plant sterols has been studied in the context of cell biological processes, signaling and overall plant development, mainly based on mutants. Due to their essential nature, genetic interference with their function causes pleiotropic developmental defects. An important alternative is to use a pharmacological approach. However, the current toolset for manipulating sterol biosynthesis in plants remains limited. Here, we probed a collection of inhibitors of mammalian cholesterol biosynthesis to identify new inhibitors of plant sterol biosynthesis. We provide evidence that imidazole-type fungicides, bifonazole, clotrimazole and econazole inhibit the obtusifoliol 14-demethylase CYP51, that is highly conserved among eukaryotes. Surprisingly, we found that the selective estrogen receptor modulator, clomiphene, inhibits sterol biosynthesis, in part by inhibiting the plant-specific cyclopropyl-cycloisomerase CPI1. These results demonstrate that rescreening of the animal sterol biosynthesis pharmacology is an easy approach for identifying novel inhibitors of plant sterol biosynthesis. Such molecules can be used as entry points for the development of plant-specific inhibitors of sterol biosynthesis that can be used in agriculture.

plant biology↗

bioRxiv2022

Phase separation-based visualization of protein-protein interactions and kinase activities in plants

Protein activities depend heavily on protein complex formation and dynamic post-translational modifications, such as phosphorylation. Their dynamic nature is notoriously difficult to monitor in planta at cellular resolution, often requiring extensive optimization and high-end microscopy. Here, we generated and exploited the SYnthetic Multivalency in PLants (SYMPL)-vector set to study protein-protein interactions (PPIs) and kinase activities in planta based on phase separation. This technology enabled easy detection of inducible, binary and ternary protein-protein interactions among cytoplasmic, nuclear and plasma membrane proteins in plant cells via a robust image-based readout. Moreover, we applied the SYMPL toolbox to develop an in vivo reporter for SnRK1 kinase activity, allowing us to visualize tissue-specific, dynamic SnRK1 activation upon energy deprivation in stable transgenic Arabidopsis plants. The applications of the SYMPL cloning toolbox lay the foundation for the exploration of PPIs, phosphorylation and other post-translational modifications with unprecedented ease and sensitivity.

plant biology↗

bioRxiv2022

Belgian endive-derived biostimulants promote shoot and root growth in vitro.

Recovering biostimulant compounds from by-products of crops is a promising strategy to add value, enhance sustainability, and increase the environmental safety of the agricultural production chain. Here, we report consistent root and shoot growth-stimulating bioactivity present in water-based extracts from Belgian endive forced roots (Cichorium intybus var. foliosum) over two consecutive harvest years. The shoot and the primary root of in vitro cultivated Arabidopsis thaliana treated with Belgian endive extract were about 30% increased in size compared to plants grown under control conditions. The ornamental species Plectranthus esculentus also showed enhanced in vitro shoot and root growth, suggesting bioactivity on a broad range of species. Fractionation of the Belgian endive extracts into aqueous and organic subfractions coupled with bio-activity measurements showed that the principal root and shoot growth-promoting ingredients are primarily water-soluble. NMR-based characterization of the bioactive aqueous fractions revealed the presence of pre-dominantly sugars and organic acids. Malate and sugars were abundant and common to all water fractions, suggesting these molecules contributed to the growth stimulation phenotype. The findings indicate that Belgian endive roots are a source for the development of organic waste-derived biostimulants with potential for application in tissue culture and putatively for soil-grown crop production.

plant biology↗