Arabidopsis Trichome Morphogenesis and the Role of Microtubules in Controlling Trichome Branch Formation

Trichomes are hairs that form on the surface of most land plants. Depending on the plant species trichomes can be multicellular or unicellular, longor short-lived, and either glandular. Trichomes mainly function as defensive structures that can protect plants from both biotic and abiotic stresses. This chapter focuses on the role of microtubules in controlling the formation of branches on Arabidopsis trichomes. Direct implication of MTs in trichome branch formation stems from studies of the subunits of MTs, which are composed of heterodimers of alpha and beta tubulin subunits. In Arabidopsis these subunits are encoded by multigene families; dominant mutations in two alpha tubulin genes have been shown to alter MT dynamics, resulting in a reduction in trichome branching. Structural analyses suggest that dynamic cortical MTs can form concentric arrays of MTs at trichome branch foci.