Two Fe-superoxide dismutase families respond differently to stress and senescence in legumes (original) (raw)

2012, Journal of Plant Physiology

Three main families of SODs may be distinguished in plants, according to the metal in the active center: CuZnSODs, MnSOD, and FeSOD. CuZnSODs have shown two sub-families localized either in plant cell cytosol or in plastids, the MnSOD family is essentially restricted to mitochondria, while FeSOD enzyme family has been typically localized into the plastid. Herein, we describe, based on a phylogenetic tree and experimental data, the existence of two FeSOD subfamilies: a plastidial localised sub-family, which is universal to plants; and a cytosolic localised FeSOD sub-family observed in determinate-forming nodule legumes. Anti-cytosolic FeSOD (cyt_FeSOD) antibodies have been employed, together with a novel antibody raised against plastidial FeSOD (p_FeSOD). Stress conditions, such as nitrate excess or drought, markedly increased cyt_FeSOD contents in soybean tissues. Also, cyt_FeSOD content and activity increased with age in both soybean and cowpea plants, while cyt_CuZnSOD isozyme was predominant during early stages. P_FeSOD in leaves decreased with most of the stresses applied but this isozyme clearly increased with abscisic acid in roots. The great differences observed for p_FeSOD and cyt_FeSOD contents in response to stress and aging in plant tissues reveals a distinct functionality, and confirm the existence of two immunologically differentiated FeSOD sub-families. The in-gel FeSOD activity patterns showed a good correlation to cyt_FeSOD contents but not to those of p_FeSOD. This fact remarkably indicates that the cyt_FeSOD is the main active FeSOD in soybean and cowpea tissues. The diversity of functions associated to the complexity of FeSOD isoenzymes depending of the location is discussed.

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