Characterizing Cell Divisions and Cell Identity in Atdek1 Mutant Embryos by Cytoskeletal Studies and Localization of the AtMLI, WUS and STM Meristem Markers

摘要

During embryogenesis cell division planes are tightly controlled illustrating the importance of correct positioning and orientation of division planes. The L1 and L2 layers further keep their clonal identity and exhibit anticlinal division while the inner cells exhibit periclinal divisions. During embryogenesis different cells assume different cell fates from original cell lineage and positional identity, which also correspond to specific gene expression profiles. DEFECTIVE KERNEL1 (DEK1) is a crucial gene for position dependent differentiation of epidermal cell formation. DEK1 possesses several characteristics that are compatible with a role in cell-cell communication in epidermal cell fate, and also L1, specification and maintenance. We here present a study of the mitotic machinery, hence tubulin and actin, in wild type and Atdekl embryos respectively. Surprisingly, based on observations of the dek1 embryo phenotype, all stages of the mitotic cycle as well as preprophase bands and early phragmoplast, were observed. However, notched and ablated cells as well as unequal cells sizes due to random cell wall deposition were frequently observed. The tissue and cell identity of different regions during Atdekl embryogenesis was monitored by in situ hybridization with the molecular markers WUS, STM, AtMLI and WOX8. WUS and STM were found to be spatially altered relatively to wild type, being enlarged and apparently less region specific. AtML1 seems to exhibit patchy L1 layer in Atdekl embryos, and WOX8 showed that the apical-basal polarity was maintained. Taken together, these results lead us to suggest that the principal mechanism underlying the Atdekl phenotypes are associated with unorganized division orientation and cell wall deposition, and lack of restriction rather than lack of specification of cell types.