Sulphur nutrition and iron plaque formation on roots of rice seedlings and their consequences for immobilisation and uptake of chromium in solution culture

Abstract

Aims The contribution of sulphur (S)-induced responses to chromium (Cr) tolerance of rice plants is not yet fully elucidated. It is hypothesised that S nutrition mitigates the accumulation and toxicity of Cr through enhanced formation of iron plaque (IP) and S-containing chelators. This study aimed to investigate the responses of iron (Fe) and Cr availability and transfer in the hydroponic rice system to added S levels. Methods We explored the influence of S nutrition on Cr accumulation in rice under a combination of Cr (VI) (+Cr, -Cr) and S (0, 1.75, 3.5, 7 mM) treatments.Results S additions at rates of 1.75 and 3.5 mM gave the least decline in root and shoot growth of rice seedlings under Cr stress. Fe concentration in shoots was consistent with the level of Cr uptake. The subcellular distribution of Cr in roots and shoots differed with varying S supply levels. Our results also revealed that S treatment at a moderate level (3.5 mM) was more effective in suppressing the bioavailability of Cr in rice shoots than were the other levels. Conclusions S-induced reduction in shoot Cr concentration, particularly from 1.75 to 3.5 mM, was likely attributed to the enhanced biosynthesis of glutathione (GSH) and phytochelatins (PCs) in roots than the enhanced physical resistance of IP induced by S. The poor barrier capacity of IP to Cr absorption in rice plants primarily ascribed to the level of applied Cr concentration and partly to the competition between Cr and S at the absorbing sites.

Speciation and distribution of chromium (III) in rice root tip and mature zone: The significant impact of root exudation and iron plaque on chromium bioavailability

“…It is generally accepted that the functional groups in IP have the potential to form a more active substrate for metal sequestration than those in Mn plaque with its unique catalytic capacity and surface activity (Ye et al, 2001;. In addition to Fe and Mn plaques, sulphur (S) containing metabolites are also effective in Cr chelation and subcellular sequestration Zandi et al, 2021), as was evident in simultaneous S and Cr depositions in the examined root regions (Fig. 3a1-2, c1-2).…”

“…Rice seed (Oryza sativa L. Var. Xiangzaoxian 31) germination (7 days on moist gauze in plastic Petri dishes in the dark at 28°C) and initial growth (21 days in black plastic containers) were conducted under controlled sterile conditions in half-strength nutrient solution (Table Supplementary (S) 1-S1), as previously described (Zandi et al, 2021). The variety was a high-quality, early-maturing, hybrid-based Yu, 2018) The seedlings of the first group, intended for iron plaque (IP) formation (Fe80-CK; Fig.…”

“…Many studies concerning the whole root system have shown that iron (hydr)oxides have a strong binding affinity for metal(loid) ions on the root surface and reduce their mobility and bioavailability, thereby inhibiting the uptake and transport of toxic metals, including Cr Zandi et al, 2022). Previous studies have shown that in the absence or weak presence of IP, higher concentrations of Cr were accumulated in root cells rather than in shoots of rice Zandi et al, , 2021, suggesting that Cr mainly deposited in root cell walls hindered its transport to the aerial organs . The hydroponic and soil culture experiments have demonstrated that an appropriate amount of IP on root surfaces could effectively adsorb Cr(III) and Cr(VI) species and reduce their transfer to the rice roots and shoots, thus decreasing Cr concentrations in rice tissues Yu et al, 2017;.…”

Significance of Shewanella Species for the Phytoavailability and Toxicity of Arsenic—A Review

“…Iron (Fe) is the fourth most available element on earth [107] and the lithosphere's second most abundant transition metal element [108]. Its oxides comprise Fe and oxygen, including ferrihydrite, lepidocrocite, goethite, and magnetite [33,[109][110][111]. These oxides are abundantly found in rocks, soil, sediments, water, and various minerals formed under different conditions [112].…”

Rice “Instant Inoculation” With Endophytic Fungus Causes Excessive Immune Response To Fusarium Proliferatum And Plant cell Death

“…In the long history of cultivation, humans have adopted farming strategies such as crop rotation to avoid soil-borne diseases, and targeted used microorganisms to against herbivores (Finkel et al 2017). At present, the use of bene cial microorganisms to improve crop health and alleviate and protect plants from stress has become a research hotspot (Zandi et al 2021;Sahoo et al 2013). Currently, the Organic Materials Review Institute (OMRI) lists 174 'microbial inoculants' products and 274 'microbial products201', as crop fertilizers or crop management tools could be applied in agriculture (Finkel et al 2017).…”