Genome-Wide Identification of the B-BOX Genes that Respond to Multiple Ripening Related Signals in Sweet Cherry Fruit

Abstract

<i>B-BOX</i> proteins are zinc finger transcription factors that play important roles in plant growth, development, and abiotic stress responses. In this study, we identified 15 <i>PavBBX</i> genes in the genome database of sweet cherry. We systematically analyzed the gene structures, clustering characteristics, and expression patterns of these genes during fruit development and in response to light and various hormones. The <i>PavBBX</i> genes were divided into five subgroups. The promoter regions of the <i>PavBBX</i> genes contain <i>cis</i>-acting elements related to plant development, hormones, and stress. qRT-PCR revealed five upregulated and eight downregulated <i>PavBBX</i> genes during fruit development. In addition, <i>PavBBX6</i>, <i>PavBBX9</i>, and <i>PavBBX11</i> were upregulated in response to light induction. We also found that ABA, BR, and GA₃ contents significantly increased in response to light induction. Furthermore, the expression of several <i>PavBBX</i> genes was highly correlated with the expression of anthocyanin biosynthesis genes, light-responsive genes, and genes that function in multiple hormone signaling pathways. Some <i>PavBBX</i> genes were strongly induced by ABA, GA, and BR treatment. Notably, <i>PavBBX6</i> and <i>PavBBX9</i> responded to all three hormones. Taken together, <i>BBX</i> proteins likely play major roles in regulating anthocyanin biosynthesis in sweet cherry fruit by integrating light, ABA, GA, and BR signaling pathways.