Using chemical genetic screening, we discovered a small molecule Cellulosin (aka endosidin20 or ES20) that causes cell swollen and inhibits plant growth, but does not disrupt global vesicle trafficking. By doing mutant screening, we obtained multiple alleles of Arabidopsis thaliana that are resistant to Cellulosin inhibition in growth. Those mutated amino acid residues are conserved across plant species. Cellulosin targets a group of cellulose synthases (CesAs) of Arabidopsis thaliana by binding to a conserved domain essential for the catalytic activity of CesA. Cellulosin may target and inhibit all subtypes of CesAs in plants. The present invention relates to Cellulosin, a cellulose synthase inhibitor, its analogs or derivatives as abroad-spectrum herbicide. The mutated genes, their protein products and a cell or a plant having those mutated genes or expressing those protein products are within the scope of this disclosure.
