Genome-wide identification and expression analysis of TCP transcription factors in Chrysanthemum indicum reveals their critical role in the response to various abiotic stresses

Chrysanthemum indicum is an important medicinal plant that has a particularly strong effect on bacteria and viruses and has antioxidant, anti-inflammatory, and immunomodulatory properties. The genes of the TCP family, a group of plant-specific transcription factors (TFs), have been found to play a crucial role in the regulation of plant growth and development as well as resistance to abiotic stress. Nevertheless, no systematic analysis of the TCP family genes in C. indicum has been performed so far. In the present study, a total of 26 non-redundant CiTCP genes were identified in the genome of C. indicum. The TCP genes were categorized into three subgroups on the basis of the phylogenetic analysis: 7, 9, and 10 genes belonged to the CIN subgroup, CYC/TB1 subgroup, and PCF subgroup, respectively. All CiTCPs were unevenly distributed across the 9 chromosomes. TCP genes in the same subgroup showed similar gene structures and conserved motifs. Gene duplication analysis revealed that segmental duplications had a significant effect on the expansion of CiTCP genes. The analysis of cis-elements revealed that CiTCP genes may be involved in the regulation of plant development, hormone response and response to abiotic stress. Expression profile analysis of the transcriptome data indicated that CiTCP genes exhibited similar or distinct expressions within different tissues and under different abiotic stresses. According to the results of quantitative RT-PCR (qRT-PCR), the expression of 15 selected genes responded strongly to various abiotic stress factors. The results of our studies could provide comprehensive insights into the TCP family genes of C. indicum for further functional investigations.