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Catalase and ascorbate peroxidase activities are not directly involveded in the silicon‐mediated alleviation of ferrous iron toxicity in rice
Author(s) -
Mbonankira Jean Elysée,
Coq Sébastien,
Vromman Delphine,
Lutts Stanley,
Nizigiyimana Aloys,
Bertin Pierre
Publication year - 2015
Publication title -
journal of plant nutrition and soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 1436-8730
DOI - 10.1002/jpln.201400068
Subject(s) - catalase , peroxidase , chemistry , ferrous , oryza sativa , antioxidant , toxicity , oxidative stress , food science , nutrient , phytotoxicity , horticulture , enzyme , botany , nuclear chemistry , biochemistry , biology , organic chemistry , gene
Silicon (Si) is the second most abundant element in the soil and can alleviate several abiotic stresses in many plant species. However, the mechanisms involved in alleviating ferrous iron (Fe 2+ ) toxicity by Si are still largely unknown, and no study has investigated the role of Si on the Fe 2+ ‐induced oxidative stress and antioxidant system in rice. Four cultivars of Asian and African rice ( Oryza sativa L. and Oryza glaberrima Steud) were grown for 4 weeks under hydroponic conditions with or without Fe 2+ (250 mg Fe 2+ L −1 ) and with or without Si (250 mg SiO 2 L −1 ). The plants that were treated with Fe 2+ suffered Fe 2+ toxicity, and Si helped to alleviate the toxicity symptoms. The bronzing index and the Fe concentration in the foliar tissue increased in the presence of Fe 2+ but decreased significantly with the application of 250 mg SiO 2 L −1 . The concentration of malonyldialdehyde, that is commonly used as an indicator of oxidative stress, increased in the foliar tissue in the presence of 250 mg Fe 2+ L −1 in the nutrient solution. The application of 250 mg SiO 2 L −1 in the plant nutrient solution treated with Fe 2+ considerably limited the increase of malonyldialdehyde. However, no significant effect of Si application on the activities of antioxidant enzymes (catalase and ascorbate peroxidase) and non‐enzymatic antioxidants (total ascorbate, reduced ascorbate, oxidized ascorbate, and the ratio of the reduced to oxidized forms) was observed in the rice plants that were grown in the presence of Fe 2+ . These results suggest that Si does not act directly on the antioxidant defense system of rice but reduces the plant Fe 2+ concentration, which reduces the oxidative stress.