-Mediated Brassinolide Biosynthesis Increases Cadmium Tolerance and Enrichment in Poplar.

Cadmium (Cd), as one of the heavy metals with biological poisonousness, seriously suppresses plant growth and does harm to human health. Hence, phytoremediation was proposed to mitigate the negative effects from Cd and restore contaminated soil. However, the internal mechanisms of detoxification of Cd used in phytoremediation are not completely revealed. In this study, we cloned the cytochrome P450 gene from hybrid poplar " No. 1" and found that the was transcriptionally upregulated by Cd stress and downregulated by the exogenous brassinolide (BR). Meanwhile, significantly promoted the poplar growth and enhanced the Cd accumulation in poplar. Compared to wild-type poplars, overexpressed lines produced higher levels of endogenous BR and showed a stronger tolerance to Cd, which revealed that may reduce the oxidative stress damage induced by Cd stress through accelerating BR synthesis. In general, has a potential superiority in regulating the plant's tolerance to Cd stress, which will provide a scientific basis and a new type of gene-modified poplar for Cd-pollution remediation.