AUTHOR=Li Xiong , Li Boqun , Jin Tao , Chen Huafang , Zhao Gaojuan , Qin Xiangshi , Yang Yongping , Xu Jianchu 

TITLE=Rhizospheric microbiomics integrated with plant transcriptomics provides insight into the Cd response mechanisms of the newly identified Cd accumulator Dahlia pinnata

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.1091056

DOI=10.3389/fpls.2022.1091056

ISSN=1664-462X

ABSTRACT=<p>Phytoremediation that depends on excellent plant resources and effective enhancing measures is important for remediating heavy metal-contaminated soils. This study investigated the cadmium (Cd) tolerance and accumulation characteristics of <italic>Dahlia pinnata</italic> Cav. to evaluate its Cd phytoremediation potential. Testing in soils spiked with 5–45 mg kg<sup>–1</sup> Cd showed that <italic>D. pinnata</italic> has a strong Cd tolerance capacity and appreciable shoot Cd bioconcentration factors (0.80–1.32) and translocation factors (0.81–1.59), indicating that <italic>D. pinnata</italic> can be defined as a Cd accumulator. In the rhizosphere, Cd stress (45 mg kg<sup>–1</sup> Cd) did not change the soil physicochemical properties but influenced the bacterial community composition compared to control conditions. Notably, the increased abundance of the bacterial phylum Patescibacteria and the dominance of several Cd-tolerant plant growth–promoting rhizobacteria (e.g., <italic>Sphingomonas</italic>, <italic>Gemmatimonas</italic>, <italic>Bryobacter</italic>, <italic>Flavisolibacter</italic>, <italic>Nocardioides</italic>, and <italic>Bradyrhizobium</italic>) likely facilitated Cd tolerance and accumulation in <italic>D. pinnata</italic>. Comparative transcriptomic analysis showed that Cd significantly induced (<italic>P</italic> &lt; 0.001) the expression of genes involved in lignin synthesis in <italic>D. pinnata</italic> roots and leaves, which are likely to fix Cd<sup>2+</sup> to the cell wall and inhibit Cd entry into the cytoplasm. Moreover, Cd induced a sophisticated signal transduction network that initiated detoxification processes in roots as well as ethylene synthesis from methionine metabolism to regulate Cd responses in leaves. This study suggests that <italic>D. pinnata</italic> can be potentially used for phytoextraction and improves our understanding of Cd-response mechanisms in plants from rhizospheric and molecular perspectives.</p>