Fig. 10

Congo red treatment increases microtubule resistance to oryzalin. Wild-type seedlings treated with Congo red and oryzalin. a, b Cell divisions (arrows) appear affected in the meristematic zone of roots treated for 6 h with 200 nM oryzalin (a) or with 10 mg L^− 1 Congo red and 200 nM oryzalin for 6 h (b). c Transition/fast elongation zone cells after 6 h exposure to 200 nM oryzalin exhibit fragmented and partially depolymerized cortical microtubules. d Congo red treatment (10 mg L^− 1 for 22 h) does not affect cortical microtubules. e Combined treatment as referred in b. Cortical microtubules appear integral, not disrupted as in roots treated with oryzalin alone (e compare to c). Scale bars: 20 μm