Foliar application of myo-inositol inhibits the growth of trifoliate orange (Poncirus trifoliata) seedlings by inducing alterations in cell wall structure and energy metabolism disorders

Exogenous myo-inositol induces alterations in leaf cell wall structure and energy metabolism disorders, which may contribute to growth inhibition of trifoliate orange seedlings.

Myo-inositol (MI) is widely distributed in all living organisms as a central molecule. In plants, de novo biosynthesis of MI is known to function in multiple aspects of plant growth and development. However, the consequences of MI accumulation in regulating plant growth, especially by exogenous supply, have received little attention. In this study, we characterized cell wall structure, target metabolites in energy metabolism, and gene expression changes related to MI metabolism after foliar application of MI to trifoliate orange seedlings. We observed that exogenous MI increases leaf and root MI levels and inhibits plant growth and dry mass accumulation in trifoliate orange seedlings. Additionally, we detected the downregulation of PtrMIPS and upregulation of PtrMIOXs in leaves due to the application of MI. Structural characterization and targeted metabolomics analysis revealed that exogenous MI induces alterations in leaf cell wall structure and energy metabolism disorders, which may contribute to growth inhibition of trifoliate orange seedlings. We propose and discuss a model to explain how exogenous MI exerts a negative impact on trifoliate orange seedling growth.