Abstract
Mitotic cortical actin microfilaments form specific distribution pattern named actin microfilament twin peaks (MFTP) involving division plane determination. Using transgenic tobacco BY-2 cells constitutively expressing GFP-ABD2, we found that actin stabilizer TIBA and Jasplakinolide (Jasp) treatment perturbed MFTP patterning and actin microfilament distribution at the periphery of spindle. In addition, the stabilizers induced oblique orientation of spindle and cell plate. To reveal a detail localization of cortical actin microfilament, we quantitatively estimated amounts of actin microfilaments by GFP-ABD2 fluorescence intensity measurements on plasma membrane and vacuolar membrane. We found that the stabilizers mainly affected on actin microfilament patterning on plasma membrane but not vacuolar membrane. Also, visualization of vacuolar membranes using fluorescence dye FM4-64 showed that complex vacuolar membrane around spindle altered into more simple form. These results imply importance of actin microfilament patterning on plasma membrane and vacuolar structures in spindle orientation.
