Different effects of gellan gum and agar on change in root elongation in Arabidopsis thaliana by polyploidization: the key role of aluminum

Abstract Purpose Agar and gellan gum have been considered to have different effects on polyploidy-dependent growth in plants. We aim to demonstrate that agar and gellan gum differently affect the change in root elongation in Arabidopsis thaliana by polyploidization and examined the physico-chemical parameters in each gelling agent to elucidate key factors that caused the differences. Methods Each polyploid strain was cultured vertically on agar and gellan gum solidified medium under fixed conditions. Root elongation rate was measured during 4–10 days after sowing. Water potential, gel hardness, and trace elements of each medium were quantified. Subsequently, the physical properties of agar medium were altered and aluminum was added to identify the factor important for change in growth by polyploidization. Results Agar promoted root elongation of polyploids more than the gellan gum. Water potential and gel hardness of agar medium were significantly higher than those of gellan gum medium. Lower water potential and gel hardness of agar medium did not affect the effects on change in polyploidy-dependent growth. Elemental analysis showed that gellan gum contained more aluminum than agar. When the polyploids were grown on agar media with additional aluminum, root elongation in tetraploids and octoploids was significantly suppressed. Conclusion This study revealed that agar and gellan gum affect the change in growth of root elongation in A. thaliana by polyploidization in different ways. The different effects on change in polyploidy-dependent growth is partially caused by aluminum in the gellan gum, which may be due to cell wall composition of polyploids.