Inhibition of photosynthetic oxygen evolution and electron transfer from the quinone acceptor QA − to QB by iron deficiency

Abstract

The effect of iron deficiency on photosynthetic electron transport in Photosystem II (PS II) was studied in leaves and thylakoid membranes of lettuce (Lactuca sativa, Romaine variety) plants. PS II electron transport was characterized by oxygen evolution and chlorophyll fluorescence parameters. Iron deficiency in the culture medium was shown to affect water oxidation and the advancement of the S-states. A decrease of maximal quantum yield of PS II and an increase of fluorescence intensity at step J and I of OJIP kinetics were also observed. Thermoluminescence measurements revealed that charge recombination between the quinone acceptor of PS II, Q(B), and the S(2) state of the Mn-cluster was strongly perturbed. Also the dark decay of Chl fluorescence after a single turnover white flash was greatly retarded indicating a slower rate of Q(A)(-) reoxidation.

A Program for Iron Economy during Deficiency Targets Specific Fe Proteins

“…It is of interest to place our findings in the context of studies that have reported on the general effects of Fe deficiency on chlorophyll synthesis and photosynthesis that have been well documented in the literature (Spiller and Terry, 1980;Andaluz et al, 2006;Nishio and Terry, 1983;Nishio et al, 1985;Sharma, 2007;Timperio et al, 2007;Laganowski et al, 2009;Msilini et al, 2011;Ciaffi et al, 2013;Paolacci et al, 2014;Rodríguez-Celma et al, 2013). Some studies on Fe depletion in plants reported that PSI was the major target of Fe deficiency (Nishio et al, 1985;Timperio et al, 2007), whereas we saw a major effect on the cytochromeb 6 f complex and less on PSI.…”

Oxidative damage and photosynthetic impairment in tropical rice cultivars upon exposure to excess iron

“…Although chlorophyll molecules may be degraded by ROS (Neves et al, 2009), these pigments were not the first target of ironinduced oxidative stress. On the other hand, iron is required for chlorophyll biosynthesis (Msilini et al, 2011), and the chlorophyll index may increase in plants that are exposed to an iron overload (Pereira et al, 2013). The reduced pigment index after seven days of Fe overload for the sensitive BR IRGA 409 cultivar is related to degradation that is mediated by oxidative stress (Gallego et al, 1996) and not by a limitation in the chlorophyll synthesis.…”

“…In oxygenic photosynthesis, Fe is a cofactor in both photosystems (PSII and PSI) and in the cytochrome (Cyt) b 6 /f complex. Moreover, it is required for chlorophyll biosynthesis and to promote the structural integrity of photosynthetic reaction centers and light-harvesting complex (LHC) subunits (Guerinot and Yi, 1994;Msilini et al, 2011;Yadavalli et al, 2012). However, the same redox properties that make Fe suitable to the electron transfer chain in photosynthesis is also responsible for its toxic effects when it is present in excess because of reactive oxygen species (ROS) overproduction (Kobayashi and Nishizawa, 2012).…”

Excess iron alters the fatty acid composition of chloroplast membrane and decreases the photosynthesis rate: a study in hydroponic pea seedlings

“…Due to its redox properties which allow its participation in electron transfer reactions (Becana et al 1998), iron is involved in many fundamental processes such as photosynthesis (Msilini et al 2011;Yadavalli et al 2012), respiration (Raven 1988;Schikora and Schmidt 2001) and nitrogen metabolism (Mills et al 2004; Moore et al 2009). Also, iron is a major constituent of important proteins and antioxidative enzymes (Jucoski et al 2013).…”

“…Also, iron is a major constituent of important proteins and antioxidative enzymes (Jucoski et al 2013). In plants, approximately 80 % of the Fe is found in the photosynthetic cells (Maathuis 2009), where Fe promotes the structural integrity of photosynthetic reaction centers and light-harvesting complex subunits, and presents specific effects on the biochemical composition and function of chloroplasts (Msilini et al 2011;Yadavalli et al 2012). Excess Fe, both in form of ferrous Fe (Fe 2? )…”