Transient increase in the transcript levels of γ-tubulin complex genes during reorientation of cortical microtubules by gravity in azuki bean (Vigna angularis) epicotyls
By hypergravity treatment, the percentage of cells with transverse microtubules was decreased, while that with longitudinal microtubules was increased in azuki bean (Vigna angularis) epicotyls. The expression of genes encoding γ-tubulin complex (VaTUG and VaGCP3) was increased transiently in response to changes in the gravitational conditions. Lanthanum and gadolinium ions, potential blockers of mechanosensitive calcium ion-permeable channels (mechanoreceptors), nullified reorientation of microtubules as well as up-regulation of expression of VaTUG and VaGCP3 by hypergravity. These results suggest that mechanoreceptors may perceive the gravity signal, which leads to a transient increase in the transcript levels of γ-tubulin complex genes and reorientation of cortical microtubules.
KeywordsAzuki bean (Vigna angularis Ohwi et Ohashi) Epicotyl Gravity Microtubule γ-Tubulin complex
We thank Professor H. Numata of Osaka City University for his advice on statistical analysis. The present study was supported in part by Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology, a Grant for Ground-based Research for Space Utilization from the Japan Space Forum, and by Sasakawa Scientific Research Grant from the Japan Science Society.
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