OsCAX2 Synergistically Enhances Cadmium Toxicity Tolerance in Rice via Dual Regulation of Vacuolar Sequestration and Redox Homeostasis

doi:10.1016/j.rsci.2026.04.011

Rice Science ›› 2026, Vol. 33 ›› Issue (5): 584-588.DOI: 10.1016/j.rsci.2026.04.011

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OsCAX2 Synergistically Enhances Cadmium Toxicity Tolerance in Rice via Dual Regulation of Vacuolar Sequestration and Redox Homeostasis

Zou Wenli¹^,²^,³^,^#, Shi Chuanlin³^,^#, Zhang Mingpei²^,^#, Chen Jingguang²^,⁴, Chen Yuetong², He Haohua³(), Meng Lijun²^,⁵(), Ye Guoyou²^,⁶()

¹ School of Life Sciences, Jiangxi Science and Technology Normal University, Nanchang 330013, China
² Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
³ Ministry of Education Key Laboratory of Crop Physiology, Ecology and Genetic Breeding, Jiangxi Agricultural University, Nanchang 330045, China
⁴ School of Agriculture, Sun Yat-sen University, Guangzhou 510275, China
⁵ Kunpeng Institute of Modern Agriculture at Foshan, Foshan 528225, China
⁶ Africa Rice Center Headquarters, Abidjan 01 BP 4029, Côte d'Ivoire

Received:2026-01-22 Accepted:2026-04-22 Online:2026-09-28 Published:2026-09-30
Contact: Ye Guoyou (y.guoyou@cgiar.org); Meng Lijun (menglijun@caas.cn); He Haohua (hhhua64@jxau.edu.cn)
About author:^#These authors contributed equally to this work

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Abstract

Zou Wenli, Shi Chuanlin, Zhang Mingpei, Chen Jingguang, Chen Yuetong, He Haohua, Meng Lijun, Ye Guoyou. OsCAX2 Synergistically Enhances Cadmium Toxicity Tolerance in Rice via Dual Regulation of Vacuolar Sequestration and Redox Homeostasis[J]. Rice Science, 2026, 33(5): 584-588.

Figures/Tables 2

Fig. 1. Phenotypic characterization of OsCAX2 knockout and overexpression lines under cadmium (Cd) stress at the seedling and maturity stages. A, Immunoblot analysis of OsCAX2 protein levels in wild type (WT, Nipponbare) and transgenic lines (OsCAX2 knockout lines: oscax2-1, oscax2-2, and oscax2-3; OsCAX2 overexpression lines: OsCAX2-OE1, OsCAX2-OE2, OsCAX2-OE3, and OsCAX2-OE4). B, Growth phenotypes of WT, vector control (VC), and OsCAX2 transgenic lines cultured hydroponically for 14 d in the absence or presence of 20 μmol/L CdCl2. Scale bars, 20 cm. C, Tissue-specific localization of OsCAX2 in root cross-sections visualized by green fluorescent protein (GFP) fluorescence under the control of its native promoter. Scale bars, 10 μm. D, Cd concentrations in roots and shoots of WT and OsCAX2 transgenic lines. E, Root-to-shoot Cd translocation ratio, calculated as (shoot Cd concentration/root Cd concentration) × 100%. F, Time-course analysis of Cd concentration in xylem sap of seedlings treated with 5 μmol/L CdCl2 for 3, 6, and 9 d. G, Cd concentrations in straws, leaves, and brown rice at maturity in field trials with 1.5 mg/kg soil Cd. In D-G, Data are presented as mean ± SD (n ≥ 6 plants per genotype). Statistical significance was determined by one-way ANOVA followed by planned comparisons (*, P < 0.05; **, P < 0.01).

Fig. 2. OsCAX2 enhances cadmium (Cd) tolerance via reactive oxygen species (ROS) scavenging, redox homeostasis, and glutathione-dependent phytochelatin (GSH-PC) synthesis, and interacts with OsHMA3. A, Phenotypes of wild type (WT) and OsCAX2 transgenic lines (OsCAX2 knockout lines: oscax2-1, oscax2-2, and oscax2-3; OsCAX2 overexpression lines: OsCAX2-OE1, OsCAX2-OE2, and OsCAX2-OE3) grown under control (0 μmol/L CdCl2), 100 μmol/L DMTU (N,N′-Dimethylthiourea, an H2O2 scavenger), 20 μmol/L CdCl2, and combined 20 μmol/L CdCl2 + 100 μmol/L DMTU treatments for 14 d. VC, Vector control. Scale bars, 10 cm. B, Cd localization in roots visualized by Leadmium Green AM staining. Scale bars, 500 μm. C, Cd concentrations in roots and shoots, and root-to-shoot Cd translocation ratio after 20 μmol/L CdCl2 and 20 μmol/L CdCl2 + 100 μmol/L DMTU exposure. D, Visualization of glutathione (GSH) accumulation in rice roots using Na-8 fluorescent probe with and without 20 μmol/L CdCl2 treatment. Scale bars, 500 μm. E, Cd concentration in roots and shoots of seedlings treated with 20 μmol/L CdCl2 alone or in combination with 100 μmol/L BSO (L-Buthionine-(S,R)-sulfoximine, a GSH synthesis inhibitor) for 14 d. F, Yeast two-hybrid assay using split-ubiquitin system to detect OsCAX2-OsHMA3 interaction. Yeast strain NMY51 co-transformed with bait/prey constructs were grown on TDO (SD/-Leu/-Trp/-His) medium. APP-Fe65 (pTSU2-APP + pNubG-Fe65) pair served as the positive control. G and H, Bimolecular fluorescence complementation (BiFC) assay in Nicotiana benthamiana leaves (G) and rice protoplasts (H). Yellow fluorescent protein (YFP) signals (yellow) indicate in vivo interaction between OsCAX2 and OsHMA3. Scale bars, 10 μm. I, Quantification of H2O2 content in roots of WT, oscax2-1, and oscax2-1/OsHMA3-OE1 with and without 20 μmol/L CdCl2 treatment. J, Cd concentrations in roots, shoots, and vacuoles, and root-to-shoot translocation ratio. In C, E, I, and J, data are mean ± SD of three independent biological replicates (n = 6 plants per genotype). Statistical significance was determined by one-way ANOVA test followed by planned comparisons with WT (*, P < 0.05; **, P < 0.01).

References 13

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OsCAX2 Synergistically Enhances Cadmium Toxicity Tolerance in Rice via Dual Regulation of Vacuolar Sequestration and Redox Homeostasis

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