Mierotubule (MT)-dependent MT nucleation by γ-tubulin is required for interphase plant cells to establish a highly dynamic cortical MT network underneath the plasma membrane that influences the deposition of cell wall materials and consequently governs patterns of directional cell expansion.Newly formed MTs either assume 40°angles or are parallel to the extant ones.To date,it has been enigmatic how the γ-tubulin complex is recruited to the sidewall of cortical MTs and initiates MT nucleation.