Genome-Wide Analysis of the CsAP2/ERF Gene Family of Sweet Orange (Citrus sinensis) and Joint Analysis of Transcriptional Metabolism under Salt Stress.

Abstract

Background: Sweet orange is an important economic crop, and salt stress can inhibit its growth and development.

Methods: In this study, we identified AP2/ERF genes in sweet orange via bioinformatics and performed a combined transcription‒metabolism analysis, which revealed for the first time the integrated molecular mechanism of salt stress regulation in sweet orange.

Key results: A total of 131 sweet orange AP2/ERF genes were identified and categorized into five groups. By comparing the tertiary protein structures of these genes with those of Arabidopsis, we found that five sweet orange genes (CsERF38, CsERF41, CsERF42, CsERF84, and CsERF110) related to salt stress and ethylene transcription are highly similar in composition and structure to those of Arabidopsis, and we hypothesize that they have similar functions. ABREs and AREs were the predominant cis-acting elements in the sweet orange AP2/ERF gene family, and both were associated with salt stress. The AP2/ERF gene family was verified to be involved in the salt stress response via qRT-PCR. According to the differentially abundant metabolite KEGG network, we chose the differentially abundant metabolites ET, GA, and JA as the primary research objects; the CsAP2/ERF gene family is an ethylene-responsive element binding factor.

Conclusion: In this study, the complete framework of the AP2/ERF gene family was constructed for the first time. A model of salt stress regulation in sweet oranges was established.