Mitochondrial structures during seed germination and early seedling development in Arabidopsis thaliana

Mitochondrial morphology and evolution have been observed during seed germination and early seedling development in Arabidopsis thaliana line 43a9 (ecotype Columbia) expressing green fluorescent protein in these organelles. Fluorescence, confocal and electronic microscopy images reveal that mitochondrial development goes through different stages, and that the organelle structure varies with cell types during these processes. Mitochondria develop from larger, isodiametric structures pre-existent in the dry seed called promitochondria. After germination, variations in mitochondrial morphology occur synchronously with cell differentiation and cell division in the course of early root development. Some promitochondria develop into intermediate structures resembling the syncytial organelles. These structures have been described in certain plants under hypoxia as intermediates for the formation of mature mitochondria. On the other hand, other promitochondria temporarily remain in the cells of the root apex.