Glandular trichome rupture in tomato plants is an ultra-fast & sensitive defense mechanism against insects.

Abstract

Trichomes, specialized hair-like structures on the surfaces of many plants, play a crucial role in defense against herbivorous insects. We investigated the biomechanics of type VI glandular trichome rupture in cultivated tomato (Solanum lycopersicum) and a wild relative (Solanum habrochaites). Using micropipette force sensors and high-speed imaging, we uncovered the rupture mechanics underlying gland bursting, highlighting the small forces and short timescales involved in this process. Additionally, we observed larvae of the Western flower thrips (Frankliniella occidentalis), a major pest in tomato cultivation, inadvertently triggering trichome rupture and accumulating glandular secretions on their bodies. We developed a method to directly measure these insect-triggered rupture forces by analyzing the trichome stalk deflections during these interactions, which yielded forces of the same order of magnitude as our micropipette measurements. These findings demonstrate how rapid gland bursting and the fluid dynamics of glandular secretions act as an efficient and swift plant defense mechanism against insect herbivory.