Involved in the formation of X-, Y-shaped and twinned plasmodesmata (PD), thus modelating PD size exclusion limit and regulating cell-to-cell transport (PubMed:22411811). Cell cycle checkpoint regulator that monitors and responds to DNA damage such as DNA cross-links, and triggers the halt of the cell cycle progression in the presence of DNA cross-linking agents. Mediates the active process of aluminum- (Al) dependent root growth inhibition and thus is required for response to Al toxicity (PubMed:22345493). Required for both early and late phases of embryo development as well as during seedling growth (PubMed:16113228, PubMed:15266054). Essential for signal transduction and development of both male and female organs (PubMed:22411811). Translocates from the cytoplasm to the nucleus in response to DNA damage mediated by treatment with AlCl(3), mitomycin C (MMC), or cisplatin (CDDP). Expressed at low levels in floral buds, leaves, stems, roots, and siliques, highest levels being in siliques that contain developing seeds. Accumulates throughout the embryo and in endosperm (PubMed:16113228). Expressed throughout the plant life cycle, from embryogenesis to seed set. Accumulates in the shoot apex. In roots, confined to the vascular system. In anthers, observed when the filaments start to elongate, and remain expressed in later stages. Constitutively expressed in gynoecia (PubMed:22411811). Defects in both embryo and seedling development, and pale yellow seeds. Die as embryos, probably because of intolerance to desiccation and abnormal protein and lipid body accumulation in mature seeds, but immature mutant seeds can be germinated in culture and lead to short life seedlings defective in shoot and root development, with reduced hypocotyls elongation in the dark (PubMed:16113228, PubMed:15266054). Seedlings accumulate less anthocyanin, are intolerant to desiccation, form trichomes on cotyledons, and have reduced accumulation of storage proteins and lipids (PubMed:16113228). Suppressor of the aluminum- (Al) hypersensitive mutant als3-1 that fails to halt root growth after Al exposure, does not accumulate CyclinB1;1 in the root tip, and fails to force differentiation of the quiescent center and is thus highly tolerant to high Al levels (PubMed:22345493). In dse1, reduced plasmodesmata (PD) formation and cell-to-cell transport during embryogenesis, due to reduced PD size exclusion limit. Dse1 embryos are developmentally retarded and accumulate anthocyanin at the junction between the cotyledons and hypocotyls, corresponding to the shoot apical meristem (SAM). Reduced apical dominance leading to the production of small abnormal flowers, often with altered organ numbers. Infertility due in part to the abnormal development of stamen with under-extended anther filaments that don't release pollen, and due in part to abnormal ovules lacking pollen attractiveness (PubMed:22411811). 'Tanmei' means short life in Japanese. Belongs to the plant DSE1 protein family. Truncated N-terminus. Truncated N-terminus.