Abscisic acid and oxidative stress implications in overall ferritin synthesis by African rice (Oryza glaberrima Steud.) seedlings exposed to short term iron toxicity

• Published in: Plant and soil 2009-11, Vol.324 (1-2), p.253-265
• Main Authors: Majerus, V, Bertin, P, Lutts, S
• Format: Article
• Language: English
• Subjects: Acid soils; Agronomy. Soil science and plant productions; Animal, plant and microbial ecology; Biological and medical sciences; Biomedical and Life Sciences; Cultivars; Ecology; Ferritins; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Hydroponics; Iron; Life Sciences; Messenger RNA; Nutrient solutions; Oxidative stress; Plant ecology; Plant Physiology; Plant roots; Plant Sciences; Plants; Regular Article; Rice; Rice fields; Seedlings; Slope stability; Soil Science & Conservation; Soil toxicity; Soil-plant relationships. Soil fertility; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Toxicity
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-009-9952-x

Iron toxicity occurs under flooded conditions such as those prevailing in lowland rice fields and is due to an excess of ferrous ions. Ferritin is a multimeric protein responsible for Fe sequestration and storage, playing a key role in Fe homeostasis. Our aim was to study the modalities of overall ferritin synthesis in different organs of young seedlings from the African rice species (Oryza glaberrima) in relation to the putative involvement of abscisic acid (ABA) and oxidative stress in signalling processes. Seedlings from a moderately resistant to iron toxicity cultivar were grown in hydroponic culture for 2 weeks and treated with 500 mg l⁻¹ Fe²⁺ in the presence or in the absence of 200 µM ABA, 50 µM methylviologen or 50 µM fluridone. Iron treatment increased iron and malondialdehyde concentration in all organs as well as ABA in roots and laminae. Although ferritin protein was detected in controls plants, iron treatment strongly reinforced its accumulation in sheaths and laminae after 24 h and 72 h. Ferritin mRNA was induced as early as 24 h after the beginning of the Fe-treatment in sheaths and, to a higher extent, in laminae. In the absence of iron treatment, exogenous ABA increased ferritin mRNA in laminae only but did not lead to further ferritin accumulation. Unexpectedly, it decreased ferritin mRNA levels in the sheaths of iron-treated plants and may thus have a dual influence depending on the considered organ. The inhibitor of ABA synthesis fluridone reduced endogenous ABA but did not compromise ferritin gene expression or ferritin synthesis, whatever the iron dose. Methyviologen application induced obvious oxidative damages but reduced ferritin synthesis. It is suggested that the signalling pathway leading to ferritin synthesis in the semi-aquatic African rice species may involve other components than those reported for typical terrestrial plants.