PT  - JOURNAL ARTICLE
AU  - Wenli Zou
AU  - Junhui Zhan
AU  - Lijun Meng
AU  - Yuetong Chen
AU  - Dandan Chen
AU  - Mingpei Zhang
AU  - Haohua He
AU  - Jingguang Chen
AU  - Guoyou Ye
TI  - The Cation/H<sup>+</sup> exchanger OsCAX2 is involved in cadmium tolerance and accumulation through vacuolar sequestration in rice
AID  - 10.1101/2022.11.22.517486
DP  - 2022 Jan 01
TA  - bioRxiv
PG  - 2022.11.22.517486
4099  - http://biorxiv.org/content/early/2022/11/24/2022.11.22.517486.short
4100  - http://biorxiv.org/content/early/2022/11/24/2022.11.22.517486.full
AB  - Excessive cadmium (Cd) in rice grains is a serious food safety problem. The development of Cd-safe varieties requires the identification of germplasms and genes with major effect on Cd accumulation but without negative effects on other important traits. Here, we reported that OsCAX2, a member of the rice Cation/H+ exchanger (CAX) family, is an important Cd transporter. OsCAX2 encodes a tonoplast-localized protein and is strongly upregulated by Cd, mainly expresses in root exodermis, parenchyma in cortex, endodermis and stele cells. Depletion of OsCAX2 resulted in enhanced Cd sensitivity and root-to-shoot translocation in rice, while overexpression of OsCAX2 significantly increased Cd tolerance and reduced Cd transport by promoting root Cd influx and vacuolar storage, which ultimately reduced Cd transport via xylem. OsCAX2 also had significant effects on tissues/organs distribution of Cd but had no effects on grain yield and agronomic traits. Importantly, the OsCAX2 overexpressing lines had more than 70% lower grain Cd accumulation, increased iron (Fe), zinc (Zn) and manganese (Mn) and reduced copper (Cu) accumulation. Therefore, OsCAX2 is an ideal gene for developing Cd-safe rice varieties via transgenic approach.Competing Interest StatementThe authors have declared no competing interest.