Identification and Analysis of the CBF Gene Family in Three Species of Acer under Cold Stress

Abstract

The C-Repeat Binding Factor (<i>CBF</i>) gene family has been identified and characterized in multiple plant species, and it plays a crucial role in responding to low temperatures. Presently, only a few studies on tree species demonstrate the mechanisms and potential functions of <i>CBFs</i> associated with cold resistance, while our study is a novel report on the multi-aspect differences of <i>CBFs</i> among three tree species, compared to previous studies. In this study, genome-wide identification and analysis of the <i>CBF</i> gene family in <i>Acer truncatum</i>, <i>Acer pseudosieboldianum</i>, and <i>Acer yangbiense</i> were performed. The results revealed that 16 <i>CBF</i> genes (five <i>ApseCBFs</i>, four <i>AcyanCBFs</i>, and seven <i>AtruCBFs</i>) were unevenly distributed across the chromosomes, and most <i>CBF</i> genes were mapped on chromosome 2 (Chr2) and chromosome 11 (Chr11). The analysis of phylogenetic relationships, gene structure, and conserved motif showed that 16 <i>CBF</i> genes could be clustered into three subgroups; they all contained Motif 1 and Motif 5, and most of them only spanned one exon. The cis-acting elements analysis showed that some <i>CBF</i> genes might be involved in hormone and abiotic stress responsiveness. In addition, <i>CBF</i> genes exhibited tissue expression specificity. High expressions of <i>ApseCBF1, ApseCBF3</i>, <i>AtruCBF1</i>, <i>AtruCBF4</i>, <i>AtruCBF6</i>, <i>AtruCBF7</i>, and <i>ApseCBF3</i>, <i>ApseCBF4</i>, <i>ApseCBF5</i> were detected on exposure to low temperature for 3 h and 24 h. Low expressions of <i>AtruCBF2</i>, <i>AtruCBF6</i>, <i>AtruCBF7</i> were detected under cold stress for 24 h, and <i>AtruCBF3</i> and <i>AtruCBF5</i> were always down-regulated under cold conditions. Taken together, comprehensive analysis will enhance our understanding of the potential functions of the <i>CBF</i> genes on cold resistance, thereby providing a reference for the introduction of <i>Acer</i> species in our country.