Besides nitrogen, micronutrients such as copper, which is a cofactor for ethylene binding (Rodr??guez et al., 1999), could also be involved.Root Waving, Skewing, and Looping Can Be Uncoupled and Do Not Necessarily Involve Cell File TwistingIt was recently proposed that root-waving and -skewing patterns in Arabidopsis roots are both the consequence of the intrinsic root righthandedness and pronounc