PLDδ, auxin, and H2O2 mediated the allelopathic effect of cycloastragenol on root growth in Arabidopsis

• DOI: 10.1016/j.jplph.2023.153929
• Publication Date: 2023-01-29T22:22:14Z
• Authors: Juantao Kong; Kai Yin; Cuixia Zhang; Xuan Liu; Ning Yang
• Keywords: 0301 basic medicine; 03 medical and health sciences; Indoleacetic Acids; Arabidopsis Proteins; Gene Expression Regulation, Plant; Arabidopsis; Phospholipase D; Hydrogen Peroxide; Plant Roots

Cycloastragenol (CAG) is a tetra-cyclic triterpenoid allelochemical. It has been widely studied in animals but rarely in plants. Here, we reported that a model allelochemical CAG inhibited primary root elongation of Arabidopsis by reducing the sizes of both the meristem and elongation zones. Phospholipase Dδ(PLDδ), hydrogen peroxide (H2O2), and auxin affected this process. After treatment with CAG, the expression of PLDδ and the activity of the Phospholipase D(PLD) enzyme increased in WT. Mutants analysis demonstrated that PLDδ negatively regulated the primary root elongation by CAG treatment. CAG treatment stimulated the accumulation of H2O2 in roots. The production of H2O2 was derived from cell wall peroxidase. Mutants analysis showed that PLDδ positively regulated the production of H2O2 by CAG treatment. CAG also decreased auxin content in the root tip by affecting the expression of auxin synthesis-related genes. PLDδ was involved in the auxin reduction mediated by CAG, but H2O2 did not participate in this process. In conclusion, PLDδ, auxin, and H2O2 mediated the inhibition of primary root growth by CAG in Arabidopsis.