Genome-Wide Characterization and Expression Analysis of the <i>SBP</i><i>-Box</i> Gene Family in Sweet Orange (<i>Citrus sinensis</i>)

• Main Authors: Na Song, Yulin Cheng, Weiye Peng, ErPing Peng, Zengling Zhao, Tiantian Liu, Tuyong Yi, Liangying Dai, Bing Wang, Yanyun Hong
• Format: Article
• Language: English
• Published: MDPI AG 2021-08-01
• Series: International Journal of Molecular Sciences
• Subjects: <i>Citrus sinensis</i>; <i>SBP</i> gene; genome-wide characterization; expression profile; abiotic and biotic stress
• Online Access: https://www.mdpi.com/1422-0067/22/16/8918
• ISSN: 1661-6596; 1422-0067

SBP-box is an important plant-specific transcription factor family and is involved in diverse biological processes. Here, we identified a total of 15 <i>SBP-BOX</i> genes in the important fruit crop sweet orange (<i>Citrus sinensis</i>) and characterized their gene structures, conserved domain and motif, chromosomal location, and <i>cis</i>-acting regulatory elements. <i>SBP</i> genes were classified into four subfamilies based on the amino acid sequence homology, and the classification is equally strongly supported by the gene and protein structures. Our analysis revealed that segmental duplication events were the main driving force in the evolution of <i>CsSBP</i> genes, and gene pairs might undergo extensive purifying selection. Further synteny analysis of the SBP members among sweet orange and other plant species provides valuable information for clarifying the CsSBP family evolutionary relationship. According to publicly available RNA-seq data and qRT-PCR analysis from various sweet orange tissues, <i>CsSBP</i> genes may be expressed in different tissues and developmental stages. Gene expression analysis showed variable expression profiles of <i>CsSBP</i> genes under various abiotic stresses, such as high and low-temperature, salt, and wound treatments, demonstrating the potential role of SBP members in sweet orange response to abiotic stress. Noticeably, all <i>CsSBP</i> genes were also downregulated in sweet orange upon the infection of an important fungal pathogen <i>Diaporthe citri</i>. Our results provide valuable information for exploring the role of <i>SBP-Box</i> in sweet orange.