Comparative evaluation of physical methods for extracting leaf trichomes

Trichomes are hairlike protuberances in plants that deter herbivores using both physical and chemical means, with pre- and post-ingestive effects. In addition, trichomes also serve as a protective layer, reducing transpiration loss, thereby improving abiotic stress tolerance. A common method for assessing the role of trichomes in defense is to extract and infuse trichomes into the artificial diet, and then examine the feeding, growth, and developmental parameters of herbivores. Although methods such as brushing, using dry ice, and shaving with a razor, have been commonly used, there is no consensus on the best and most efficient method for trichome extraction. In the current study, to optimize the ideal method to extract trichomes, we tested three common methods with some modifications, such as flash freezing and brushing, shaving using a scalpel, and vortexing followed by freezing. Here, we used representative species from both eudicots and monocots with significant trichome diversity. For eudicots, we selected three cultivated plant species: tomato, sunflower, and Mexican squash, and two wild plant species: wild sunflower and wild squash, and for monocots, we used the model plant, rice. The efficiency of each method was examined using a combination of light and scanning electron microscopy. The results suggest that freezing followed by brushing is the most efficient and ideal method for extracting trichomes and can be recommended for eudicots. However, none of the evaluated methods were effective for the monocot rice.