Strategies in a metallophyte species to cope with manganese excess

The effect of exposure to high Mn concentration was studied in a metallophyte species, Erica andevalensis, using hydroponic cultures with a range of Mn concentrations (0.06, 100, 300, 500, and 700 mg L-1). At harvest, biomass production, element uptake, and biochemical indicators of metal stress (leaf pigments, organic acids, amino acids, phenols, and activities of catalase, peroxidase, superoxide dismutase) were determined in leaves and roots. Increasing Mn concentrations led to a decrease in biomass accumulation, and tip leaves chlorosis was the only toxicity symptom detected. In a similar way, photosynthetic pigments (chlorophylls a and b, and carotenoids) were affected by high Mn levels. Among organic acids, malate and oxalate contents in roots showed a significant increase at the highest Mn concentration, while in leaves, Mn led to an increasing trend in citrate and malate contents. An increase of Mn also induced an increase in superoxide dismutase activity in roots and catalase activity in leaves. As well, significant changes in free amino acids were induced by Mn concentrations higher than 300 mg L-1, especially in roots. No significant changes in phenolic compounds were observed in the leaves, but root phenolics were significantly increased by increasing Mn concentrations in treatments. When Fe supply was increased 10 and 20 times (7–14 mg Fe L-1 as Fe-EDDHA) in the nutrient solutions at the highest Mn concentration (700 mg Mn L-1), it led to significant increases in photosynthetic pigments and biomass accumulation. Manganese was mostly accumulated in the roots, and the species was essentially a Mn excluder. However, considering the high leaf Mn concentration recorded without toxicity symptoms, E. andevalensis might be rated as a Mn-tolerant speciesinfo:eu-repo/semantics/publishedVersio

Early responses to manganese (Mn) excess and its relation to antioxidant performance and organic acid exudation in barley cultivars

Manganese (Mn) is an essential micronutrient for plants, and is necessary for biochemical and physiological processes. The objective of this research was to determine the early responses to Mn excess and its relation to antioxidant performance mechanisms and organic acid exudation in commercial barley cultivars. We determined early responses to Mn excess in four barley cultivars (Barke, Tatoo, Scarlett, Sebastian), which were subjected to increasing Mn concentrations (2.4-150-350-750-1500 µM Mn), pH 4.8, under nutrient solution during seven days. Results showed that plant growth parameters: biomass, length and relative growth rate (RGR) were negatively altered with the higher Mn treatments. Antioxidant performance such as antioxidant activity (AA) and antioxidant enzymes such as superoxidase dismutase (SOD) were activated in presence of excess Mn. Oxalate was the major organic acid roots exudate, and the cultivar Sebastian had the highest oxalate exudation. In conclusion, Tatoo and Sebastian are proposed as the most Mn tolerant cutvars given that the biomass parameters were not affected by increasing Mn doses, showing major oxalate exudation. It is suggested that the mechanisms associated to Mn alleviation could be attributed to SOD, AA and organic acid production, mainly oxalate, in tolerant cultivars (Sebastian, Tatoo) together to significant decrease of total phenols (TP) in shoot of sensitive cultivars (Barke and Scarlett). Non-enzymatic barriers were not related to early responses, and an enzymatic barrier and oxalate exudation were considered as early indicators of Mn stress, projecting that the tolerance of Mn-tolerant cultivars could increase under field conditions. © 2018, Sociedad Chilena de la Ciencia del Suelo. All rights reserved

Shoot and root ionome responses to nitrate supply in grafted grapevines are rootstock genotype dependent

Background and Aims[br/] Both rootstocks and mineral nutrition, particularly nitrogen (N), are known to affect many aspects of plant development including the control of scion vigour. In this study, we investigated the role of the rootstock genotype in grafted grapevine responses to N supply in terms of the root and leaf ionomes, scion vigour and whole plant biomass.[br/] [br/] Methods and Results[br/] Vitis vinifera cv. Cabernet Sauvignon was grafted on two rootstock genotypes known to confer high and low vigour. Plants were grown for 60 days under three levels of nitrate supply. Stem, leaf, trunk and root biomass, and the concentration of 13 macroelements and microelements in roots and leaves were measured. High scion vigour was associated with a high concentration of elements in the leaves. The concentration of some elements in the leaves, such as phosphorus, was affected by the N supply differently in the two scion/rootstock combinations.[br/] [br/] Conclusion[br/] Differences in rootstock conferred vigour were associated with particular shoot and root ionome profiles, and these responses were dependent on N supply.[br/] [br/] Significance of the Study[br/] These results demonstrate that rootstocks alter scion growth and the leaf ionome in response to N supply