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Journal of Cell Science

Year: 2009  |  Volume: 122  |  Issue: 13  |  Page No.: 2208 - 2217

A mutation in the Arabidopsis {gamma}-tubulin-containing complex causes helical growth and abnormal microtubule branching

M Nakamura and T. Hashimoto

Abstract

Plant cortical microtubules are mainly nucleated on previously established microtubules, grow at a narrow range of angles to the wall of mother microtubules, and eventually are released from the nucleation sites. These nucleation events are thought to be regulated by -tubulin-containing complexes. We here show that a null mutation of Arabidopsis GCP2, a core subunit of the -tubulin-containing complex, severely impaired the development of male and female gametophytes. However, a missense mutation in the conserved grip1 motif, called spiral3, caused a left-handed helical organization of cortical microtubule arrays, and severe right-handed helical growth. The spiral3 mutation compromises interaction between GCP2 and GCP3, another subunit of the complex, in yeast. In the spiral3 mutant, microtubule dynamics and nucleation efficiency were not markedly affected, but nucleating angles were wider and more divergently distributed. A spiral3 katanin double mutant had swollen and twisted epidermal cells, and showed that the microtubule minus ends...

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