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Nitric oxide improves internal iron availability in plants
Magdalena Graziano1, María Verónica Beligni, Lorenzo Lamattina
1Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, CC 1245, 7600 Mar del Plata, Argentina.
Plant Physiology
|December 14, 2002
Summary
Nitric oxide (NO) application effectively reversed iron deficiency symptoms in maize plants by improving chloroplast development, not by increasing iron uptake. This suggests NO influences iron availability within plants.
Area of Science:
- Plant Physiology
- Biochemistry
- Molecular Biology
Background:
- Iron deficiency severely impacts plant growth by inhibiting chlorophyll synthesis and chloroplast development.
- Internal iron transport mechanisms within plant cells, particularly to chloroplasts, are not fully understood.
- Nitric oxide (NO), a reactive molecule, can interact with metal ions.
Purpose of the Study:
- To investigate the role of nitric oxide (NO) in alleviating iron deficiency symptoms in maize.
- To explore the effects of NO on chloroplast development and iron metabolism in plants.
- To determine if NO influences iron uptake or internal iron distribution.
Main Methods:
- Maize plants were subjected to iron deficiency and treated with various NO donors (sodium nitroprusside, S-Nitroso-N-acetylpenicillamine) and gaseous NO.
- NO scavengers were used to confirm the specificity of NO's effects.
- Chlorosis, chloroplast structure (via electron microscopy), and plant iron content were analyzed.
- Experiments included wild-type and iron-inefficient maize mutants (yellow stripe1, yellow stripe3).
Main Results:
- NO application (sodium nitroprusside, S-Nitroso-N-acetylpenicillamine, gaseous NO) effectively prevented or reversed leaf interveinal chlorosis in iron-deficient maize.
- Electron microscopy revealed that NO treatment led to the development of normal chloroplasts with well-formed grana in iron-deficient plants.
- NO treatment did not significantly increase total plant iron content on a fresh weight basis.
- NO application also rescued the chlorotic phenotype in iron-inefficient maize mutants impaired in iron uptake.
- NO scavengers exacerbated chlorosis in iron-replete plants, suggesting a role for endogenous NO.
Conclusions:
- Nitric oxide plays a significant role in mitigating the physiological effects of iron deficiency in maize.
- NO's beneficial action appears to be related to improving the availability or delivery of iron within the plant, rather than enhancing root iron uptake.
- These findings highlight a novel biological function of NO in plant iron nutrition and chloroplast biogenesis.