Fig. 2

SIM imaging of PPB formation in Col-0 and ktn1-2. a Early PPB in Col-0 (bracket). With few exceptions (arrowheads) the cortical cytoplasm outside of the PPB is cleared from microtubules. b An example of a very broad PPB (bracket) in ktn1-2. c, d Another example of an early ktn1-2 PPB showing a wealth of cortical microtubules outside the PPB (c, rectangle) and excessive microtubule branching (d; arrowheads) in some instances. e An abnormally broad late PPB (long bracket) of an early prophase ktn1-2 cell showing an incomplete part (short brackets) and the formation of perinuclear spindle (arrow). f By comparison to (e), a late PPB of a Col-0 early prophase cell is shown. PPB is considerably more narrow. g, h Overview (g) and detail (h) of another abnormal preprophase cell of ktn1-2 showing excessive de novo branched formation of microtubules (arrowheads). Bars in a–c, e, g = 10 μm; f = 5 μm; d, h = 1 μm