Identification of genes from the ICE-CBF-COR pathway under cold stress in Aegilops- Triticum composite group and the evolution analysis with those from Triticeae

Abstract

Adverse environmental conditions limit various aspects of plant growth, productivity, and ecological distribution. To get more insights into the signaling pathways under low temperature, we identified 10 C-repeat binding factors (CBFs), 9 inducer of CBF expression (ICEs) and 10 cold-responsive (CORs) genes from Aegilops-Triticum composite group under cold stress. Conserved amino acids analysis revealed that all CBF, ICE, COR contained specific and typical functional domains. Phylogenetic analysis of CBF proteins from Triticeae showed that these CBF homologs were divided into 11 groups. CBFs from Triticum were found in every group, which shows that these CBFs generated prior to the divergence of the subfamilies of Triticeae. The evolutionary relationship among the ICE and COR proteins in Poaceae were divided into four groups with high multispecies specificity, respectively. Moreover, expression analysis revealed that mRNA accumulation was altered by cold treatment and the genes of three types involved in the ICE-CBF-COR signaling pathway were induced by cold stress. Together, the results make CBF, ICE, COR genes family in Triticeae more abundant, and provide a starting point for future studies on transcriptional regulatory network for improvement of chilling tolerance in crop.

Keywords: CBF; COR; Cold stress; ICE; Triticeae.

Fig. 1

Phylogenetic analysis of CBF proteins in Triticeae. The tree was constructed using the neighbor-joining (NJ) method with a Poisson correction model and 1000 bootstrap replicates. The tree was divided into 11 groups, and the solid points before the sequence names indicate the gene isolated in this study

Fig. 2

Sequence structure analysis of CBF proteins. a Structure schematic of CBF proteins. All CBF amino acid sequences were divided into two parts including the N-terminal and the C-terminal domain. In the N-terminal, all CBF proteins contained an AP2 DNA binding domain, signature 1 (PKRPAGRTKFxExRHP) and signature 2 (DSAWR). In the acidic C-terminal, three distinct groups were present depending on the C-terminal sequence discrepancies (fragment 1, 2, 3, 4), and all CBF proteins contained another conserved domain (LWSC/Y). The length of schemes does not reflect protein size. b Details of the N-terminal structure of CBF proteins. All characteristics were marked in the figture. c Details of the C-terminal structure of CBF proteins. All characteristics were marked in the figture

Fig. 3

Phylogenetic analysisof ICE proteins in Poaceae. The tree was constructed using the NJ method with a Poisson correction model and 1000 bootstrap replicates. The tree was divided into 4 groups

Fig. 4

Phylogenetic analysisof COR proteins in Poaceae. The tree was constructed using the NJ method with a Poisson correction model and 1000 bootstrap replicates. The tree was divided into 4 groups with high multispecies specificity

Fig. 5

Expression analysis of ICE, CBF, COR genes under cold stress. The Y-axis indicates the normalized fold change in expression of each ICE, CBF, COR genes. The X-axis indicates the cold (4 °C) treatments for 0, 2, 4, 8, 12, 24 h. Error bars represented the standard error of the mean, and the asterisks represented the significance