Inhibition of Enhances Plant Tolerance to Zn Toxicity by Upregulating Pathways Related to Iron Nutrition.

The identification of the key genes regulating plant tolerance to Zn stress is important for enhancing the Zn phytoremediation of targeted plants. Here, we showed that the T-DNA insertion-induced inhibition of the () gene in the mutant greatly improved Zn tolerance, as indicated by increased biomass production and reduced leaf chlorosis. The complementation in the mutant abolished the improvement of Zn tolerance. Unexpectedly, the mutant had higher and comparable Zn concentrations in the roots and citrate effluxer shoots, respectively, compared to wild-type plants. As a result, the shoots and roots of mutants had 53% and 193% more Zn accumulation than the wild-type plants, respectively. RNA-seq analyses revealed that the Fe nutrition-related genes were upregulated in mutants, especially under Zn stress conditions. Therefore, the mutants had a greater Fe concentration and a higher Fe/Zn ratio than the wild-type plants exposed to Zn toxicity. Further study showed that the differences in Zn tolerance between and wild-type plants were minimized by eliminating Fe or supplementing excessive Fe in the growth medium. Taken together, the T-DNA insertion-induced inhibition of BTS improves plant Zn tolerance by optimizing Fe nutrition; thus, the knockdown of BTS may be a promising approach for improving Zn phytoremediation efficiency.