Abstract
Newly divided cells in plants undergo significant elongation before their differentiation. Because plant cells are enclosed in rigid cell walls, cellulose microfibrils, which are deposited in cell walls in a transverse direction to the axis of elongating cells, are critical for the directionality of cell elongation. Because of their coaliment with microfibrils, transversely oriented cortical microtubles lying underneath plasma membrane have be proposed to regulate the microfibril orientation.
Arabidopsis spiral2 (spr2) mutant is defective in directional cell elongation and shows right-handed helical growth in axial organs. We reveled that the SPR2 gene encodes a novel protein with HEAT repeats. The fusion protein of SPR2 and GFP localized to the cortical microtubles in various tissues. Recombinant SPR2 proteins were sedimented in vitro with taxol-stabilized microtubles. Our results suggest that SPR2 is a novel microtuble-associated protein and might be required for proper organization of cortical microtubles.
