Chloroplast-localized transporter OsNTP1 mediates cadmium transport from root to shoot and sugar metabolism in rice

Abstract

Cadmium (Cd) is an element with high toxicity to living organisms, and its accumulation in rice grains poses a threat to human health. In this study, we report a novel nickel-transport family protein, OsNTP1, that is involved in Cd transport from root to shoot. Heterologous expression of OsNTP1 in yeast enhanced Ni and Cd tolerance. In rice, the transporter OsNTP1 is localized at the chloroplast and the expression of OsNTP1 was rapidly induced by Cd treatment. Under Cd²⁺ treatment, the Cd content in the shoots of OsNTP1 -RNAi lines was significantly increased. Notably, knockdown of OsNTP1 significantly reduces Cd accumulation in the grains, highlighting its critical role in minimizing Cd contamination in edible parts of the plant. In addition, knockout or knockdown OsNTP1 also increased sensitivity to sucrose. Sucrose treatment led to more starch particles at the OsNTP1 -RNAi shoot base, and exogenous sucrose can alleviate the inhibitory effects of Cd stress on sugar metabolism and starch synthesis in OsNTP1 -RNAi lines. The present study provides a new genetic resource for breeding low-Cd grains and exploring the response mechanisms of sugar metabolism to Cd stress. • Heterologous expression of OsNTP1 in yeast enhanced Ni and Cd tolerance. • OsNTP1 is localized at the chloroplast and the expression of OsNTP1 was rapidly induced by Cd treatment. • Cd content in brown rice of OsNTP1 -RNAi lines were significantly lower than that in wild-type. • OsNTP1 plays an important role in Cd uptake and root to shoot translocation • Down-regulated of OsNTP1 increased the sensitivity to sucrose and affected sucrose metabolism and starch accumulation.