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Tobacco plants (Nicotiana tabacum L.) exhibit considerable potential for phytoremediation of soil cadmium (Cd) pollutants, owing to their substantial biomass and efficient metal accumulation capabilities. The reduction of Cd accumulation in tobacco holds promise for minimizing Cd intake in individuals exposed to cigar smoking. NRAMP transporters are pivotal in the processes of Cd accumulation and resistance in plants; however, limited research has explored the functions of NRAMPs in tobacco plants. In this investigation, we focused on NtNRAMP6c , one of the three homologs of NRAMP6 in tobacco. We observed a robust induction of NtNRAMP6c expression in response to both Cd toxicity and iron (Fe) deficiency, with the highest expression levels detected in the roots. Subsequent subcellular localization and heterologous expression analyses disclosed that NtNRAMP6c functions as a plasma membrane-localized Cd transporter. Moreover, its overexpression significantly heightened the sensitivity of yeast cells to Cd toxicity. Through CRISPR-Cas9-mediated knockout of NtNRAMP6c , we achieved a reduction in Cd accumulation and an enhancement in Cd resistance in tobacco plants. Comparative transcriptomic analysis unveiled substantial alterations in the transcriptional profiles of genes associated with metal ion transport, photosynthesis, and macromolecule catabolism upon NtNRAMP6c knockout. Furthermore, our study employed plant metabolomics and rhizosphere metagenomics to demonstrate that NtNRAMP6c knockout led to changes in phytohormone homeostasis, as well as shifts in the composition and abundance of microbial communities. These findings bear significant biological implications for the utilization of tobacco in phytoremediation strategies targeting Cd pollutants in contaminated soils, and concurrently, in mitigating Cd accumulation in tobacco production destined for cigar consumption. [Display omitted] • Regulation of Cd accumulation is important for reducing Cd intake for human beings exposed to cigar smoking. • NtNRAMP6c is a plasma membrane-localized Cd transporter. • NtNRAMP6c knockout enhanced Cd resistance. • NtNRAMP6c knockout significantly altered the microbial compositions and abundances. [ABSTRACT FROM AUTHOR]

Root-knot nematode (RKN) disease is a destructive soil disease that affects crop health and causes huge losses in crop production. To explore the relationships between soil environments, rhizobacterial communities, and plant health, rhizosphere bacterial communities were analyzed using metagenomic sequencing in tobacco samples with different grades of RKN disease. The results showed that the community structure and function of the plant rhizosphere were significantly correlated to the RKN disease. RKN density and urease content were key factors affecting the rhizosphere bacterial community. Urease accelerated the catabolism of urea and led to the production of high concentrations of ammonia, which directly suppressed the development of RKNs or by improving the nutritional and growth status of microorganisms that were antagonistic to RKNs. Further experiments showed that the suppression role of ammonia should be attributed to the direct inhibition of NH 3. The bacterial members that were positively correlated with RKN density, contained many plant cell wall degrading enzymes, which might destroy plant cell walls and promote the colonization of RKN in tobacco roots. The analysis of metatranscriptome and metabolism demonstrated the role of these cell wall degrading enzymes. This study offers a comprehensive insight into the relationships between RKNs, bacteria, and soil environmental factors and provides new ideas for the biological control of RKNs. • RKN density and urease content were key factors affecting the rhizosphere community. • Some functional gene categories had strong relationships with the infection of RKN. • Urease might have significant impacts on RKN disease. • Bacteria with cell wall degrading enzymes might promote the colonization of RKNs. [ABSTRACT FROM AUTHOR]

Growth of multicellular organisms relies on diversity in gene expression between cells of different functions. Single-cell transcriptomes can facilitate analysis of cell specific response to different environmental stress. By performing single-nucleus sequencing of tobacco (Nicotiana tabacum) seedlings, 13,028 single cells were profiled. We identified 29 clusters corresponding to 18 cell types, some of which were verified by in situ hybridization. Developmental trajectory results and comparisons of ligand-receptor repertoires revealed cell specific functions of different cell types in tobacco seedlings. Divergent and conserved genes between tobacco and rice (Oryza sativa) highlighted some cell specific and species specific gene features. Our study generated the first single-cell transcriptome atlas of tobacco seedling, providing a wide range of information into the role and functions of different cell types. • It was first singe-cell atlas of tobacco seedling, including 13,028 cells. • 29 clusters corresponding to 18 cell types were identified. • Cell-specific functions for different cell types were revealed. • Some species-cell specific features were identified by conservation analysis. [ABSTRACT FROM AUTHOR]