Drug Delivery in Plants Using Silk Microneedles

New systems for agrochemical delivery in plants will foster precise agricultural practices and provide new tools to study plants and design crop traits, as standard spray methods suffer from elevated loss and limited access to remote plant tissues. Silk‐based microneedles can circumvent these limitations by deploying a known amount of payloads directly in plants’ deep tissues. However, plant response to microneedles’ application and microneedles’ efficacy in deploying physiologically relevant biomolecules are unknown. Here, it is shown that gene expression associated with Arabidopsis thaliana wounding response decreases within 24 h post microneedles’ application. Additionally, microinjection of gibberellic acid (GA3) in A. thaliana mutant ft‐10 provides a more effective and efficient mean than spray to activate GA3 pathways, accelerating bolting and inhibiting flower formation. Microneedle efficacy in delivering GA3 is also observed in several monocot and dicot crop species, i.e., tomato (Solanum lycopersicum), lettuce (Lactuca sativa), spinach (Spinacia oleracea), rice (Oryza Sativa), maize (Zea mays), barley (Hordeum vulgare), and soybean (Glycine max). The wide range of plants that can be successfully targeted with microinjectors opens the doors to their use in plant science and agriculture. The utility of silk‐based microneedles is demonstrated in delivery of plant hormones (gibberellic acid) to Arabidopsis thaliana and several crop species with minimal wounding response and higher efficiency and efficacy than foliar spray. Microneedle‐mediated delivery allows tissues restricted by current delivery methods to be reached and opens the door to a new tool for plant science and precision agriculture.