NAC transcription factors from Aegilops markgrafii reduce cadmium concentration in transgenic wheat

Background and aims Cadmium (Cd) is one of the heavy metal elements that are most harmful to human health, and the transmission of Cd through the food chain is a global issue. Aegilops markgrafii is a wild relative of the cultivated wheat that is tolerant of high levels of Cd. The objective of this study is to investigate the NAC transcription factors (TFs) involved in Cd tolerance in Ae. markgrafii and to verify their function in transgenic wheat. Methods We cloned NAC TFs from Ae. markgrafii plants exposed to excessive Cd treatment. The expression profiles of NAC TFs in root and shoot tissues were examined using qRT-PCR. Transgenic wheat was obtained via Agrobacterium-mediated transformation. Finally, we examined Cd concentrations in transgenic wheat under excess Cd treatment. Results We identified three NAC TFs and classified them into four subfamilies. Sequence alignments showed that the NAC TFs had conserved N-terminal domains but varied C-terminal domains. Expression profiles of NAC TFs showed about 150-fold up-regulation in the transcription of AemNAC2 and AemNAC3 under excess Cd treatment. Overexpression of AemNAC2 in the wheat cultivar 'Bobwhite' led to reduce Cd concentration in the root, shoot and grains. Conclusions AemNAC2 is an important TF that contributes to Cd tolerance in wheat.