Nitric Oxide Effect on Mowing Tolerance of Tall Fescue (Festuca Arundinacea Schreb.) Roots via Antioxidant Defense and Plant Hormones

Mowing is important in maintaining quality of the turf. The objective of this study was to determine the effect of Nitric Oxide (NO) on tall fescue after mowing, and provide theoretical basis for molecular breeding of turf grass. In our study, exogenous NO significantly increased the relative growth rate compared to the control. The higher relative growth rate was associated with higher activity of Peroxides (POD), SuperOxide Dismutase (SOD), Catalase (CAT) and Ascorbate Peroxidase (APX). Expression of CuZn- SOD, CAT-A, and APX4 increased in roots treated with NO after mowing. In addition, exogenous NO significantly increased the concentration of Indole-3-Acetic Acid (IAA), Gibberellic Acid (GA), Cytokinin (CK) and Abscisic Acid (ABA) compared to the control, which likely linked to an increase in Nitric Oxide Synthase (NOS)-like activity and endogenous NO release in tall fescue roots. These results suggested that mowing increased NOS-like activity, leading to elevated endogenous NO levels. NO might act as a signaling molecule, increasing plant hormone content, as well as up-regulating gene expression and enhancing the activity of antioxidant enzymes, thereby protecting against injuries caused by mowing and promoting re-growth of tall fescue.