Calcium Plays a Double-Edged Role in Modulating Cadmium Uptake and Translocation in Rice

Abstract

Cadmium (Cd) contamination in soils poses great risks to both agricultural production and human health. Calcium (Ca) is an essential element playing a significant role in protecting plants against Cd toxicity. However, how Ca affects Cd uptake and translocation in rice is still not fully elucidated. In this study, the regulatory role of Ca in Cd uptake and upward translocation was investigated in rice at different growth stages. Our results showed that the supplement of 5 mM Ca significantly reduced Cd uptake by rice roots, because of their competition for Ca-permeable channels as an absorption site and Ca-induced downregulation of OsNRAMP1 and OsNRAMP5. However, Ca application facilitated the upward translocation of Cd by both upregulating OsHMA2 to induce xylem loading of Cd and downregulating OsHMA3 to reduce vacuolar sequestration of Cd. Such contrary results suggested a double-edged role of Ca in regulating root Cd uptake and root-to-shoot Cd translocation in rice. Although it increased Cd content in the aboveground vegetative tissues during the whole growth period, the addition of 5 mM Ca eventually decreased Cd content in rice grains at the ripening stage. All these results suggest that Ca-based amendments possess great potential for the production of low-Cd rice grains.

Molecular Interaction and Evolution of Jasmonate Signaling With Transport and Detoxification of Heavy Metals and Metalloids in Plants

“…Here, we highlight that the roles of Ca 2+ in the mitigation of heavy metals toxicity that may partially rely on activating JA (Figure 3). Ca 2+ influxes and phosphorylation status are immediately changed when plants are subject to insect attack (Yan et al, 2018a), As(V) (Yu et al, 2012), and Cd (Zhang et al, 2020a). Ca channels and transporters including autoinhibited Ca 2+ -ATPases (ACAs), GLRs, cyclic nucleotide-gated channels (CNGCs), two-pore Ca 2+ channels (TPCs), the hyperosmolality-gated calcium-permeable channels (OSCAs), Ca 2+ /H + exchangers (CAXs), and annexin proteins (ANNs) are involved in the biosynthesis and signaling of JA.…”

“…Calcium signaling is involved in JA regulatory network and also plays important roles in the transmission of the signals generated by heavy metals and metalloids stress to physiological responses (Zhang et al, 2020a). Comparative genomic and evolutionary studies reveal the widespread occurrence of channels, pumps, and transporters likely to be involved in Ca signaling (Verret et al, 2010;Edel et al, 2017;Thor et al, 2020).…”

Calcium Oxide Nanoparticles Have the Role of Alleviating Arsenic Toxicity of Barley

“…As and Ca contents were measured using an inductively coupled plasma mass spectrometer (ICP-MS, iCAP RQ, Thermo scientific, United States). In addition, As accumulation and translocation factors were calculated according to Zhang et al (2020) .…”

Calcium Biofortification of Crops–Challenges and Projected Benefits

“…Lower doses of Ca promote Cd uptake and translocation in plants, but higher doses reduce the Cd uptake in the roots (Eller and Brix, 2015). The accumulation of Cd in plants was significantly reduced with increasing Ca concentrations in rice plants; Ca diminished root Cd uptake and stimulated translocation of Cd from roots to shoots (Zhang et al, 2020a).…”