Figure 3.
Variation in SPR2 Dynamics in Different Cell Types
(A) SPR2 is deposited at newly formed MT crossovers. The sequence shown was taken in WT Ler pavement cells. SPR2 is localized at the MT plus end and moves to the crossover as the plus end crosses another MT. Arrowheads point to the MT plus end and the SPR2 particles it deposits at crossovers. Arrow points at a complex MT crossover, which the growing MT will join following a 32.3° reorientation from the initial trajectory (dotted line). Scale bar represents 2 μm.
(B) Kymograph analysis of SPR2 behavior in SPR2-GFP pavement and petiole cells. The top panels show a projection of a 100 s movie sequence. The white line indicates the MT that was selected for the corresponding kymograph analysis shown at the bottom (9.4 μm for petiole cells; 14.4 μm for pavement cells). Arrows indicate particles that are stationary during the course of the movie in pavement cells and mobile particles in petiole cells.
(C) Quantitative analysis of SPR2-GFP particle movement in pavement cells (n = 253 particles; n = 18 cells) and petiole cells (n = 258 particles; n = 16 cells). The average particle velocity is 0.24 μm/min in pavement cells versus 2.4 μm/min in petiole cells.