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

Abstract

Iron plays a pivotal role in the redox reactions of photosynthesis and metabolic processes such as chlorophyll synthesis. Iron availability in waterlogged soils can reach toxic levels and promote oxidative stress. Fe toxicity is the most concerning of stresses for rice in many lowland environments around the world and may cause severe impairments in rice photosynthesis. This study aimed to investigate the extension of oxidative stress after excess Fe exposure and its effects on the photosynthesis of rice cultivars with differential sensitivity. Three Brazilian rice cultivars (EPAGRI 107, BRSMG SELETA and BR IRGA 409) were grown in Hoagland nutrient solution (pH 4.0) with two Fe-EDTA doses corresponding to excess Fe (7 mM) and control (0.009 mM) treatments. After just three days of excess Fe exposure, there was a significant increase in iron concentration in the shoots. The BR IRGA 409 cultivar exhibited higher Fe accumulation in its shoots, and the EPAGRI 107 cultivar recorded the lowest values, which were below the critical toxicity level, as a resistance strategy. Impairment in light energy partitioning and oxidative damage became evident before changes in stomatal resistance, chlorophyll content, maximal PSII quantum yield or visual symptoms for the most sensitive cultivar (BR IRGA 409). The photosynthesis limitations, in addition to the impairment of excess energy dissipation in rice from iron toxicity, are the results of oxidative damage.

Growth Performance and Antioxidant Enzyme Activities of Advanced Mutant Rice Genotypes under Drought Stress Condition

“…The reduction in relative chlorophyll content was possibly associated with the oxidative damage development in the chloroplast and also caused the lipid membrane peroxidation of the thylakoids to induce and, thus, degradation of chlorophyll [29]. Drought stresses resulted in reduced chlorophyll content in leaves which might be associated with an increase in chlorophyll density [30].…”

The developmental and iron nutritional pattern of PIC1 and NiCo does not support their interdependent and exclusive collaboration in chloroplast iron transport in Brassica napus

“…5) and only slight increase in the leaf Fe content (Fig. 4) under supraoptimal Fe nutrition indicates that Fe retention in the roots may have contributed to the avoidance of Fe toxicity (Wheeler et al 1985;Becker and Asch 2005;Sperotto et al 2010;Pinto et al 2015). In contrast, Fe deficiency inhibited the accumulation of Fe in the leaves and chloroplasts, only a slight increase was measured in the Fe content of 6th leaves during the leaf area expansion.…”

Assessment of Iron Toxicity in Tropical Grasses with Potential for Revegetating Mined Areas

“…The absorption and excessive accumulation of iron in plants can increase the formation of rOS, therefore causing oxidative damage in plants [4,25]. Increases in MDA, a lipid peroxidation byproduct, are considered an important indicator of oxidative stress in plants [13,26]. The low MDA concentration presented by P. densum and E. crus-galli after exposure to different iron concentrations is therefore indicative of an rOS control mechanism.…”