Role of ferritin in the rice tolerance to iron overload

Abstract

Plants ordinarily face iron (Fe) deficiency, since this mineral is poorly available in soils under aerobic conditions. Nonetheless, wetland and irrigated rice plants can be exposed to excess, highly toxic Fe. Ferritin is a ubiquitous Fe-storage protein, important for iron homeostasis. Increased ferritin accumulation resulting from higher Fe availability was shown in some plant species. However, the role of ferritin in tolerance mechanisms to Fe overload in rice is yet to be established. In this study, recombinant rice ferritin was expressed in Escherichia coli, producing an anti-rice ferritin polyclonal antibody which was used to evaluate ferritin accumulation in two rice (Oryza sativa L.) cultivars, either susceptible (BR-IRGA 409) or tolerant (EPAGRI 108) to Fe toxicity. Increased ferritin mRNA and protein levels resulting from excess Fe treatment were detected in both cultivars, with higher ferritin protein accumulation in EPAGRI 108 plants, which also reached lower shoot Fe concentrations when submitted to iron overload. The tolerance mechanism to excess Fe in EPAGRI 108 seems to include both restricted Fe translocation and increased ferritin accumulation. This is the first work that shows higher accumulation of the ferritin protein in an iron-excess tolerant Oryza sativa cultivar, providing evidence of a possible role of this protein in iron tolerance mechanisms.

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

“…The results reported here indicate that the resistance to excess iron toxicity that was exhibited by the EPAGRI 107 cultivar may involve a mechanism of avoidance, which prevents high levels of iron in shoots. It may be achieved by the regulation of Fe uptake, as seen by Silveira et al, (2009). In fact, the oxidation of Fe 2+ to Fe 3+ at the root surface, resulting in a typical orange precipitate known as iron plaque, was reported previously for the EPAGRI 107 cultivar (Pereira et al, 2014).…”

“…The roots become dark brown in color and develop poorly, and exhibit a scanty and coarse aspect (Becker and Asch, 2005;Silveira et al, 2009). Iron toxicity also reduces growth and yield (Dorlodot et al, 2005), causes nutritional disorders (Pereira et al, 2014) and severe impairment in rice photosynthesis (Pereira et al, 2013).…”

Genetic Improvement of Iron Toxicity Tolerance in Rice-Progress, Challenges and Prospects in West Africa

“…To date, molecular mechanisms under excess Fe conditions have not been studied in detail. The expression level of ferritin genes, OsFER1 and OsFER2, were increased in leaves under Fe toxicity conditions (Silveira et al, 2009;Stein et al, 2009). A recent study revealed the presence of seven QTLs and three QTLs for leaf bronzing score in a F8 recombinant inbred population derived from IR 29/Pokkali and a backcross population derived from Nipponbare/Kasalath/Nipponbare, respectively (Wu et al, 2014).…”

Detection of Chromosomal Regions Affecting Iron Concentration in Rice Shoots Subjected to Excess Ferrous Iron Using Chromosomal Segment Substitution Lines betweenJaponicaandIndica

“…However, molecular mechanisms under the excess ferrous iron conditions have not been studied in detail, except that the expression level of ferritin genes, OsFER1 and OsFER2, were increased in leaves under the excess ferrous iron conditions (Silveira et al, 2009;Stein et al, 2009).…”