Effects of Exogenous Manganese (Mn) on Mineral Elements, Polyamines and Antioxidants in Apple Rootstock Malus robusta Rehd.

Abstract

Manganese (Mn) is one of the essential microelements in all organisms. However, high level of Mn is deleterious to plants. In this study, the effects of exogenous manganese application on mineral element, polyamine (PA) and antioxidant accumulation, as well as polyamine metabolic and antioxidant enzyme activities, were investigated in Malus robusta Rehd., a widely grown apple rootstock. High level of Mn treatments decreased endogenous Mg, Na, K and Ca contents, but increased Zn content, in a Mn-concentration-dependent manner. Polyamine metabolic assays revealed that, except the content of perchloric acid insoluble bound (PIS-bound) spermine, which increased significantly, the contents of putrescine (Put), spermidine (Spd) and spermine (Spm) all decreased progressively, accompanied with the decreased activities of arginine decarboxylase (ADC, EC 4.1.1.19) and ornithine decarboxylase (ODC, EC 4.1.1.17), and the increased activities of diamine oxidase (DAO, EC 1.4.3.6) and polyamine oxidase (PAO, EC 1.5.3.3). Further antioxidant capacity analyses demonstrated that contents of anthocyanin, non-protein thiols (NPT) and soluble sugar, and the activities of guaiacol peroxidase (POD, EC 1.11.1.7), catalase (CAT, EC 1.11.1.6) and superoxide dismutase (SOD, EC 1.15.1.1), also increased upon different concentrations of Mn treatments. Our results suggest that endogenous ion homeostasis is affected by high level of Mn application, and polyamine and antioxidant metabolism is involved in the responses of M. robusta Rehd. plants to high level of Mn stress.

Manganese sulfate application promotes berry flavonoid accumulation in Vitis vinifera cv. ‘Cabernet Sauvignon’ by regulating flavonoid metabolome and transcriptome profiles

“…Anthocyanins have also been reported to intercept light signals and act as antioxidants by directly neutralizing ROS and protecting cells from oxidative damage under stress. 14 Qi et al 18 applied exogenous Mn to apples and found that it improved the leaf anthocyanin concentration and antioxidant capacity, in consistency with the results of this study. Treatment with a high Mn concentration may therefore also be beneficial for responding to changing environments.…”

“…These were associated with the regulation of biological processes and signal transduction, and carbohydrate and energy metabolism. Leaf Mn treatment also enhanced the concentration of salicylic acid significantly and promoted the synthesis of ethylene and jasmonic acid in grapevine leaves, induced activity in guaiacol peroxidase, catalase, and superoxide dismutase in apple leaves, and enhanced the content of soluble solids in cucumber leaves 8,18,19 …”

“…Leaf Mn treatment also enhanced the concentration of salicylic acid significantly and promoted the synthesis of ethylene and jasmonic acid in grapevine leaves, induced activity in guaiacol peroxidase, catalase, and superoxide dismutase in apple leaves, and enhanced the content of soluble solids in cucumber leaves. 8,18,19 However, the effect of MnSO 4 on berry composition remains unclear, especially regarding the accumulation of flavonoids and its effect on regulatory mechanisms. The aim of this study was therefore to explore the effect and mechanism of action of Mn on flavonoid metabolism in grape berries by applying three different concentrations on Mn (Hoagland's solution; 0.5, 5, and 1000 μmol•L −1 of MnSO 4 •H 2 O) to 'Cabernet Sauvignon' (Vitis vinifera L.) plants grown in a greenhouse, and to provide a theoretical basis for Mn fertilizer management in V. vinifera viticulture.…”