Ferritins are a superfamily of iron-storage proteins that are found in all living organisms with the exception of yeast. They are ubiquitous, iron-binding proteins that play an important role in cellular iron homoeostasis, storing up to 4,500 iron atoms in their central cavities. In plants, ferritins are preferentially localised in the plastids but are also found in mitochondria. Ferritin expression is developmentally regulated and plays a role in the synthesis of iron-containing proteins that are involved in photosynthesis in the early stages of plant development. It accumulates in seeds during embryo maturation to provide iron during germination, allowing for the proper formation of the photosynthetic apparatus. Ferritins are transcriptionally controlled by iron, which induces the production of reactive oxygen species (ROS) in the Fenton reaction in its free form and thus has a high potential for toxicity. Several reports have shown that the transcription of ferritin in plants may be induced by environmental factors, such as drought, salinity, cold, light intensity, pathogen attack, NO and ozone, which then stimulate ROS production. Studies that have analysed other stresses, such as those caused by herbicides and heavy metals, have also shown increased expression levels of the ferritin genes. These reports suggest that ROS induces ferritin transcription and that ferritin plays a protective role by capturing free iron and limiting oxidative damage to the cell. Recent evidence of ferritins effectively participating in the defensive machinery of plants under oxidative stress was obtained from transgenic plants that overexpressed ferritin genes. This review is focused on the protective role of ferritin in plants that are threatened by oxidative damage in response to biotic and abiotic stresses. © 2012 by Nova Science Publishers, Inc. All rights reserved. 6582Apel, K., Hirt, H., Reactive oxygen species: metabolism, oxidative stress, and signal Transduction (2004) Annual Review of Plant Biology, 55, pp. 373-399Arnaud, N., Murgia, I., Boucherez, J., Briat, J.-F., Cellier, F., Gaymard, F., An iron-induced nitric oxide burst precedes ubiquitin-dependent protein degradation for Arabidopsis AtFer1 ferritin gene expression (2006) Journal of Biological Chemistry, 281, pp. 23579-23588Arosio, P., Ingrassia, R., Cavadini, P., Ferritins: a family of molecules for iron storage, antioxidation and more (2009) Biochimica et Biophysica Acta -General Subjects, 1790, pp. 589-599Atienza, S.G., Faccioli, P., Perrotta, G., Dalfino, G., Zschiesche, W., Humbeck, K., Stanca, A.M., Cattivelli, L., Large scale analysis of transcripts abundance in barley subjected to several single and combined abiotic stress conditions (2004) Plant Science, 167, pp. 1359-1365Bottcher, A., Nobile, P., Martins, P., Conte, F., Azevedo, R., Mazzafera, P., A role for ferritin in the antioxidant system in coffee cell cultures (2011) Biometals, 24, pp. 225-237Briat, J.-F., Duc, C., Ravet, K., Gaymard, F., Ferritins and iron storage in plants (2010) Biochimica et Biophysica Acta -General Subjects, 1800, pp. 806-814Briat, J.-F., Lebrun, M., Plant responses to metal toxicity (1999) Comptes Rendus de l'Académie des Sciences -Series III -Sciences de la Vie, 322, pp. 43-54Briat, J.-F., Ravet, K., Arnaud, N., Duc, C., Boucherez, J., Touraine, B., Cellier, F., Gaymard, F., New insights into ferritin synthesis and function highlight a link between iron homeostasis and oxidative stress in plants (2010) Annals of Botany, 105, pp. 811-822Busch, A., Rimbauld, B., Naumann, B., Rensch, S., Hippler, M., Ferritin is required for rapid remodeling of the photosynthetic apparatus and minimizes photo-oxidative stress in response to iron availability in Chlamydomonas reinhardtii (2008) The Plant Journal, 55, pp. 201-211Clement, M., Lambert, A., Herouart, D., Boncompagni, E., Identification of new up-regulated genes under drought stress in soybean nodules (2008) Gene, 426, pp. 15-22Déak, M., Horváth, G.V., Davletova, S., Török, K., Sass, L., Vass, I., Barna, B., Dudits, D., Plants ectopically expressing the iron-binding protein, ferritin, are tolerant to oxidative damage and pathogens (1999) Nature Biotechnology, 17, pp. 192-196Dellagi, A., Rigault, M., Segond, D., Roux, C., Kraepiel, Y., Cellier, F., Briat, J.-F., Expert, D., Siderophore-mediated upregulation of Arabidopsis ferritin expression in response to Erwinia chrysanthemi infection (2005) The Plant Journal, 43, pp. 262-272Donnini, S., Castagna, A., Ranieri, A., Zocchi, G., Differential responses in pear and quince genotypes induced by Fe deficiency and bicarbonate (2009) Journal of Plant Physiology, 166, pp. 1181-1193Fobis-Loisy, I., Loridon, K., Lobreaux, S., Lebrun, M., Briat, J.F., Structure and differential expression of 2 maize ferritin genes in response to iron and abscisic-acid (1995) European Journal of Biochemistry, 231, pp. 609-619Gao, L., Yan, X., Li, X., Guo, G., Hu, Y., Ma, W., Yan, Y., Proteome analysis of wheat leaf under salt stress by two-dimensional difference gel electrophoresis (2D-DIGE) (2011) Phytochemistry, , In Press, Corrected ProofGarc a-Mata, C., Lamattina, L., Nitric oxide induces stomatal closure and enhances the adaptive plant responses against drought stress (2001) Plant Physiology, 126, pp. 1196-1204García Mata, C., Lamattina, L., Cassia, R.O., Involvement of iron and ferritin in the potato-Phytophthora infestans Interaction (2001) European Journal of Plant Pathology, 107, pp. 557-562Hegedus, A., Janda, T., Horváth, G.V., Dudits, D., Accumulation of overproduced ferritin in the chloroplast provides protection against photoinhibition induced by low temperature in tobacco plants (2008) Journal of Plant Physiology, 165, pp. 1647-1651Hintze, K., Theil, E., Cellular regulation and molecular interactions of the ferritins (2006) Cellular and Molecular Life Sciences, 63, pp. 591-600Jaspers, P., Kangasjärvi, J., Reactive oxygen species in abiotic stress signaling (2010) Physiologia Plantarum, 138, pp. 405-413Laufberger, V., Sur la cristallisation de la ferritine (1937) Bulletin de la Société de chimie biologique, 19, pp. 1575-1582Li, Q.-Y., Niu, H.-B., Yin, J., Wang, M.-B., Shao, H.-B., Deng, D.-Z., Chen, X.-X., Li, Y.-C., Protective role of exogenous nitric oxide against oxidative-stress induced by salt stress in barley (Hordeum vulgare) (2008) Colloids and Surfaces B: Biointerfaces, 65, pp. 220-225Liu, G., Greenshields, D.L., Sammynaiken, R., Hirji, R.N., Selvaraj, G., Wei, Y., Targeted alterations in iron homeostasis underlie plant defense responses (2007) Journal of Cell Science, 120, pp. 596-605Lobreaux, S., Briat, J.F., Ferritin accumulation and degradation in different organs of pea (Pisum Sativum) during development (1991) Biochemical Journal, 274, pp. 601-606Long, J.C., Merchant, S.S., Photo-oxidative stress impacts the expression of genes encoding iron metabolism components in Chlamydomonas (2008) Photochemistry and Photobiology, 84, pp. 1395-1403Majerus, V., Bertin, P., Lutts, S., Abscisic acid and oxidative stress implications in overall ferritin synthesis by African rice (Oryza glaberrimat Steud.) seedlings exposed to short term iron toxicity (2009) Plant and Soil, 324, pp. 253-265Murgia, I., Briat, J.F., Tarantino, D., Soave, C., (2001) Plant ferritin accumulates in response to photoinhibition but its ectopicPlant Physiology and Biochemistry, 39, pp. 797-805. , overexpression does not protect against photoinhibitionMurgia, I., Delledonne, M., Soave, C., Nitric oxide mediates iron-induced ferritin accumulation in Arabidopsis (2002) The Plant Journal, 30, pp. 521-528Nagajyoti, P., Lee, K., Sreekanth, T., Heavy metals, occurrence and toxicity for plants: a review (2010) Environmental Chemistry Letters, 8, pp. 199-216Parker, R., Flowers, T.J., Moore, A.L., Harpham, N.V.J., An accurate and reproducible method for proteome profiling of the effects of salt stress in the rice leaf lamina (2006) Journal of Experimental Botany, 57, pp. 1109-1118Petit, J.M., Briat, J.F., Lobreaux, S., Structure and differential expression of the four members of the Arabidopsis thaliana ferritin gene family (2001) Biochemical Journal, 359, pp. 575-582Ravet, K., Touraine, B., Boucherez, J., Briat, J.F., Gaymard, F., Cellier, F., Ferritins control interaction between iron homeostasis and oxidative stress in Arabidopsis (2009) Plant Journal, 57, pp. 400-412Shi, S., Wang, G., Wang, Y., Zhang, L., Zhang, L., Protective effect of nitric oxide against oxidative stress under ultraviolet-B radiation (2005) Nitric Oxide, 13, pp. 1-9Stein, R.J., Ricachenevsky, F.K., Fett, J.P., Differential regulation of the two rice ferritin genes (OsFER1 and OsFER2) (2009) Plant Science, 177, pp. 563-569Theil, E., Coordinating responses to iron and oxygen stress with DNA and mRNA promoters: the ferritin story (2007) Biometals, 20, pp. 513-521Van Wuytswinkel, O., Vansuyt, G., Grignon, N., Fourcroy, P., Briat, J.-F., Iron homeostasis alteration in transgenic tobacco overexpressing ferritin (1999) The Plant Journal, 17, pp. 93-97Wei, J.Z., Theil, E.C., Identification and characterization of the iron regulatory element in the ferritin gene of a plant (soybean) (2000) Journal of Biological Chemistry, 275, pp. 17488-17493Xi, L., Xu, K., Qiao, Y., Qu, S., Zhang, Z., Dai, W., Differential expression of ferritin genes in response to abiotic stresses and hormones in pear (Pyrus pyrifolia) (2010) Molecular Biology Reports, pp. 1-9Zancani, M., Peresson, C., Biroccio, A., Federici, G., Urbani, A., Murgia, I., Soave, C., Macrì, F., Evidence for the presence of ferritin in plant mitochondria (2004) European Journal of Biochemistry, 271, pp. 3657-3664Zhang, L., Si, J., Zeng, F., An, L., Molecular cloning and characterization of a ferritin gene upregulated by cold stress in Chorispora bungeana (2009) Biological Trace Element Research, 128, pp. 269-283Zok, A., Oláh, R., Hideg, É., Horváth, V., Kós, P., Majer, P., Váradi, G., Szegedi, E., Effect of Medicago sativa ferritin gene on stress tolerance in transgenic grapevine (2010) Plant Cell, Tissue and Organ Culture, 100, pp. 339-344