Identification of ABF/AREB gene family in tomato ( <i>Solanum lycopersicum</i> L.) and functional analysis of <i>ABF/AREB</i> in response to ABA and abiotic stresses

Abstract

Abscisic acid (ABA) is a plant hormone that plays an important regulatory role in plant growth and stress response. The <i>AREB</i> (ABA-responsive element binding protein)/<i>ABF</i> (ABRE-binding factor) are important ABA-signaling components that participate in abiotic stress response. However, genome-scale analysis of <i>ABF/AREB</i> has not been systemically investigated in tomato. This study was conducted to identify tomato <i>ABF/AREB</i> family members and analyze their response to ABA and abiotic stresses. The results show that a total of 10 <i>ABF/AREB</i> members were identified in tomato, which are randomly distributed on five chromosomes. Domain analysis showed that these members exhibit high protein similarity, especially in the basic leucine zipper (bZIP) domain region. Subcellular localization analysis indicated that all 10 <i>ABF/AREB</i> members are localized in the nucleus. Phylogenetic tree analysis showed that tomato <i>ABF/AREB</i> genes are divided into two groups, and they are similar with the orthologs of other plants. The analysis of <i>cis</i>-acting elements showed that most tomato <i>ABF/AREB</i> genes contain a variety of hormones and stress-related elements. Expression profiles of different tissues indicated that <i>SlABF2</i> and <i>SlABF10</i> play an important role in fruit ripening. Finally, qRT-PCR analysis revealed that 10 tomato <i>ABF/AREB</i> genes respond to ABA, with <i>SlABF3</i> being the most sensitive. <i>SlABF3</i>, <i>SlABF5</i> and <i>SlABF10</i> positively respond to salt and cold stresses. <i>SlABF1</i>, <i>SlABF3</i> and <i>SlABF10</i> are significantly induced under UV radiation treatment. <i>SlABF3</i> and <i>SlABF5</i> are significantly induced in osmotic stress. Overall, this study may provide insight into the role of tomato <i>ABF/AREB</i> homologues in plant response to abiotic stresses, which laid a foundation for future functional study of <i>ABF/AREB</i> in tomato.