The NtSPL Gene Family in Nicotiana tabacum : Genome-Wide Investigation and Expression Analysis in Response to Cadmium Stress.

The SQUAMOSA promoter binding protein-like (SPL) family genes play an important role in regulating plant growth and development, synthesis of secondary metabolites, and resistance to stress. Understanding of the role of the family in tobacco is still limited. In this study, 42 genes were identified from the genome of the tobacco variety TN90. According to the results of the conserved motif and phylogenetic tree, the genes were divided into eight subgroups, and the genes in the same subgroup showed similar gene structures and conserved domains. The -acting element analysis of the promoters showed that the genes were regulated by plant hormones and stresses. Twenty-eight of the 42 genes can be targeted by miR156. Transcriptome data and qPCR results indicated that the expression pattern of miR156-targeted genes was usually tissue specific. The expression level of miR156 in tobacco was induced by Cd stress, and the expression pattern of showed a significant negative correlation with that of miR156. These results suggest that miR156- may mediate the tobacco response to Cd stress. This study lays a foundation for further research on the function of the gene and provides new insights into the involvement of genes in the plant response to heavy metal stress.