Differential expression of the multiplicated silicon transporter genes at different stages of morphogenesis of daughter frustule of the freshwater diatom Ulnaria acus

Diatoms are known for their unique ability to form species-specific silicon exoskeletons (shells) richly decorated with various ornaments, outgrowths, and holes. The absorption of silicic acid from the environment by cells is a critical step in this process. It is known that silicic acid is transported into diatom cells by silicic acid transport proteins (SIT). However, the mechanism and regulation of the work of proteins of this family currently remain insufficiently studied. In the present study, we attempted to determine the stages of daughter valve morphogenesis in the pennate freshwater diatom Ulnaria acus and to assess the expression level of sit-m genes encoding multiplexed silicon transporters. The experiment showed that simultaneously with the formation of the main axial element of the daughter valves (sternum) and first-order branching (virga), the level of sit-tri gene expression increases. While, during the formation of second-order branching (vimin) and areoles, an increase in the level of sit-td gene expression was noted, with a simultaneous decrease in sit-tri. Based on the data obtained, it can be assumed that after duplication of sit genes in the diatom genome, with the formation of multiplexed structures, their subfunctionalization occurs at different stages of daughter valve morphogenesis.