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 <100 up to 1350 mg Fe kg-1 DM. In situ synchrotron-based X-ray fluorescence microscopy showed that increased Fe supply caused an overall decrease in Mn in the leaf tissue but had little effect on the pattern of its distribution. Similarly, X-ray absorption spectroscopy identified only slight effects of Fe supply on Mn speciation in leaf tissues. Thus, the results of this study indicate that increased Fe supply ameliorated Mn toxicity in soybean and sunflower largely through decreased Mn uptake and translocation to leaf tissues rather than through changes in Mn distribution or speciation within the leaves.

中文翻译：

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使用基于同步加速器的X射线荧光显微镜和X射线吸收光谱法评估铁对大豆和向日葵中锰毒性的影响。

在化学性质相似的情况下，Mn和Fe在植物中起着许多重要作用，但对这些作用的程度和机理了解甚少。大豆（对锰敏感的物种）的叶子出现轻度的萎黄病和小的黑斑，并且在营养液（pH 5.6； 3 mM离子强度）中含有30μMMn和0.6μMFe的三叶形叶子变形。在0.6μMFe下，向日葵（一种耐Mn的物种）的下部互生叶在30μMMn时发生绿叶病，在400μMMn时发生浅绿叶病和坏死。溶液中30和300μMFe的浓度减轻了这些典型的Mn毒性症状，并将Mn的浓度从> 3000降低到大约。所有叶片组织中的干重为800 mg kg-1。正如预期的那样，铁供应的增加使叶片中的铁从<100增加到1350 mg Fe kg-1 DM。原位基于同步加速器的X射线荧光显微镜显示，铁供应的增加导致叶片组织中Mn的总体下降，但对其分布方式几乎没有影响。同样，X射线吸收光谱法仅发现铁供应对叶片组织中锰形态的轻微影响。因此，这项研究的结果表明，增加铁的供应量可通过减少对锰的吸收和向叶片组织的转移而不是通过改变叶片中Mn的分布或形态来改善大豆和向日葵中的Mn毒性。X射线吸收光谱法仅发现了铁供应对叶片组织中锰形态的轻微影响。因此，这项研究的结果表明，增加铁的供应量可通过减少对锰的吸收和向叶片组织的转移而不是通过改变叶片中Mn的分布或形态来改善大豆和向日葵中的Mn毒性。X射线吸收光谱法仅发现了铁供应对叶片组织中锰形态的轻微影响。因此，这项研究的结果表明，增加铁的供应量可以通过减少对锰的吸收和向叶片组织的转移而不是通过改变叶片中Mn的分布或形态来改善大豆和向日葵中的Mn毒性。