Overexpression of OsCAX2 in indica rice reduces cadmium accumulation in grains without yield loss

Hu, Zhi; Zou, Wenli; Ye, Huijing; Ma, Jie; Meng, Lijun; Chen, Jingguang; Ye, Guoyou

Overexpression of OsCAX2 in indica rice reduces cadmium accumulation in grains without yield loss

Autores

Editor

Elsevier
KeAi Communications Co. Ltd.

Descripción

Cadmium (Cd) exposure poses significant health risks to humans, and the International Agency for Research on Cancer has classified it as a Group I carcinogen. Cadmium undergoes minimal metabolism in the human body; consequently, prolonged Cd2+ exposure can cause severe damage to multiple organs including the liver, kidneys, lungs, bones, and immune system (Shao et al. 2024). Rice, one of the three global staple crops, and Cd exposure in humans primarily occurs the consumption of contaminated rice grains. The contribution of rice to the total dietary Cd intake is over 50% for non-smoking Asian populations (Chen et al. 2018; Shi et al. 2020). Current mitigation strategies focus on soil remediation and breeding low Cd accumulating cultivars (Zhao et al. 2022). Key regulatory genes such as OsHMA3 and OsNRAMP5 have been identified: enhanced-function haplotypes of OsHMA3 reduce grain Cd accumulation by 50–90% without yield loss, while OsNRAMP5 knockout achieves >90% Cd reduction but severely impairs manganese uptake (Ueno et al. 2010; Sasaki et al. 2014, Sasaki et al. 2012; Tang et al. 2017; Lu et al. 2019; Zhou et al. 2019). Additionally, OsLCT1, which regulates Cd2+ transport to rice grains, serves as a potential target for gene editing strategies (Uraguchi et al. 2011). Southern China’s indica rice-growing regions face elevated Cd contamination risks due to soil acidification, industrial pollution, and the inherently higher Cd accumulation capacity of indica than japonica subspecies (Guo et al. 2010; Zhu et al. 2016; Yang et al. 2018). This study demonstrates that overexpression of a Ca2+/H+ exchanger-encoding gene OsCAX2 in the indica rice cultivar ‘Huanghuazhan (HHZ)’, the most widely cultivated cultivar in southern China, significantly reduced Cd2+ concentration in brown rice.