セミナー情報

Microtubules play central roles on plant developments and morphogenesis　throughout unique microtubule arrays: cortical microtubules, preprophase band, the non-centrosomal spindle and phragmoplast.

The well-defined function of cortical microtubule array is to control the movement of cellulase synthase complexes. The net orientation in which cellulose microfibrils are aligned influences profoundly the directionality of expansion and therefore, by controlling this orientation, the cortical array itself plays a major role in regulating morphogenesis. In addition to guiding cellulose synthesis, numerous other functions for the cortical array have been postulated over the years, including: membrane trafficking, movement of transcription factors, and translation suppression. Cortical microtubules are also apparently involved in signal transduction pathways for auxin-induced lateral root formation, gravitropism of roots, response to aluminum and self-incompatibility. These reports indicate the function of the cortical microtubule array is likely to be broader than is generally recognized.

In general, the organization and function of microtubule networks is accomplished by proteins interacting with microtubules, especially microtubule-associated proteins, MAPs. Here, we coupled affinity purification to high performance mass spectroscopy and identified more than 1500 proteins from an Arabidopsis thaliana MAP fraction. From these proteins, we found two unidentified MAPs family by examining GFP fusion proteins in transgenic lines. Furthermore, we found both cytoplasmic ribonucleoproteins and organellar proteins are abundant in the MAPs fraction and these organelles and cytoplasmic RNA granules relate to microtubule in cells. We will discuss possible functions of cortical microtubules based on the results of proteomics and imaging approaches.