Evaluating effects of iron on manganese toxicity in soybean and sunflower using synchrotron-based X-ray fluorescence microscopy and X-ray absorption spectroscopy

• Published in: Metallomics 2019-12, Vol.11 (12), p.297-211
• Main Authors: Blamey, F. Pax C, Li, Cui, Howard, Daryl L, Cheng, Miaomiao, Tang, Caixian, Scheckel, Kirk G, Noerpel, Matt R, Wang, Peng, Menzies, Neal W, Kopittke, Peter M
• Format: Article
• Language: English
• Subjects: Absorption spectroscopy; Chlorophyll - metabolism; Chlorosis; Dose-Response Relationship, Drug; Drug Interactions; Fluorescence; Fluorescence microscopy; Glycine max - drug effects; Glycine max - metabolism; Helianthus; Helianthus - drug effects; Helianthus - metabolism; Ionic strength; Iron; Iron - pharmacology; Leaves; Manganese; Manganese - metabolism; Manganese - pharmacology; Microscopy; Microscopy, Fluorescence - methods; Necrosis; Organic chemistry; Plant Leaves - drug effects; Plant Leaves - metabolism; Plant tissues; Soybeans; Speciation; Sunflowers; Synchrotrons; Toxicity; Translocation; X ray absorption; X-ray absorption spectroscopy; X-Ray Absorption Spectroscopy - methods; X-ray fluorescence; X-ray spectroscopy; X-Rays
• ISSN: 1756-5901; 1756-591X
• DOI: 10.1039/c9mt00219g

With similar chemistry, Mn and Fe interact in their many essential roles in plants but the magnitude and mechanisms involved of these interactions are poorly understood. Leaves of soybean (a Mn-sensitive species) developed a mild chlorosis and small dark spots and distorted trifoliate leaves with 30 μM Mn and 0.6 μM Fe in nutrient solution (pH 5.6; 3 mM ionic strength). At 0.6 μM Fe, lower alternate leaves of sunflower (a Mn-tolerant species) were chlorotic at 30 μM Mn and had a pale chlorosis and necrosis at 400 μM Mn. A concentration of 30 and 300 μM Fe in solution alleviated these typical symptoms of Mn toxicity and decreased the concentration of Mn from >3000 to ca. 800 mg kg −1 dry mass (DM) in all leaf tissues. As expected, increased Fe supply increased Fe in leaves from