Novel small molecule modulators of plant growth and development identified by high-content screening with plant pollen
Background: Small synthetic molecules serve as valuable tools in agricultural biotechnology, offering alternatives to genetic engineering and providing unique capabilities to modulate plant growth and development.
Results: We developed a high-throughput phenotypic screening method to investigate the molecular mechanisms underlying plant growth using haploid populations of pollen cells. These cells rapidly germinate to form pollen tubes, allowing compounds that act as growth inhibitors or stimulators to be identified within an assay lasting no longer than 8 hours. This approach highlights the potential for prioritizing chemicals for future mechanism-focused studies in plants. Using this assay, we identified 65 chemical compounds that influenced pollen development. These compounds were further evaluated for their effects Usp22i-S02 on seed growth in Nicotiana tabacum (tobacco) and Arabidopsis thaliana. When 7-day-old Arabidopsis seedlings were grown in the presence of these chemicals, 22 compounds reduced root length by 4.76% to 49.20% compared to untreated controls. Conversely, two structurally related thiazolidine compounds promoted root growth, increasing root length by 129.23% and 119.09%, respectively. Additionally, a pollen tube growth-promoting compound (S-02), belonging to the benzazepin chemical class, enhanced Arabidopsis root length by 126.24%.
Conclusions: This study demonstrates the utility of a pollen tube-based assay for screening small-molecule libraries to identify biologically active compounds. Pollen tubes provide an ultra-rapid and efficient screening tool capable of analyzing large chemical libraries in short timeframes. Combined with seed germination assays, this broadly applicable high-throughput protocol enables the identification of plant growth inhibitors and stimulators, facilitating advancements in plant biotechnology.