Accumulation of a myosin XI subclass into phragmoplasts in tobacco cultured cells BY-2.

Abstract

We have identified two types of myosins, 170-kDa and 175-kDa myosins, responsible for cytoplasmic streaming in BY-2 cells. On the basis of analysis of primary sequence of each myosin heavy chain gene, these myosins were classified into myosin XI. Localization studies using antibodies against 175-kDa myosin showed that this myosin is accumulated into phragmoplasts. The accumulation depended on actin filaments, because of the suppression by latrunculin B, while brefeldin A did not affect the accumulation, indicating that this phenomenon is not related to the transport of Golgi vesicles. We examined the effects of BDM to further explore the function of 175-kDa myosin in the phragmoplasts. Although the accumulation of this myosin into phragmoplasts was induced even in the presence of 30 mM BDM, the morphology of newly synthesized cell plates was appeared to be aberrant. We will discuss the role of 175-kDa myosin XI in the phragmoplasts.