Genome-Wide Analysis of the YABBY Transcription Factor Family in Pineapple and Functional Identification of AcYABBY4 Involvement in Salt Stress

Abstract

The plant-specific transcription factor gene family, YABBY, belongs to the subfamily of zinc finger protein superfamily and plays an essential regulatory role in lateral organ development. In this study, nine <i>YABBY</i> genes were identified in the pineapple genome. Seven of them were located on seven different chromosomes and the remaining two were located on scaffold 1235. Through protein structure prediction and protein multiple sequence alignment, we found that <i>AcYABBY3</i>, <i>AcYABBY5 and AcYABBY7</i> lack a C2 structure in their N-terminal C2C2 zinc finger protein structure. Analysis of the <i>cis</i>-acting element indicated that all the seven pineapple <i>YABBY</i> genes contain multiple MYB and MYC elements. Further, the expression patterns analysis using the RNA-seq data of different pineapple tissues indicated that different <i>AcYABBYs</i> are preferentially expressed in various tissues. RT-qPCR showed that the expression of <i>AcYABBY2</i>, <i>AcYABBY3</i>, <i>AcYABBY6 and AcYABBY7</i> were highly sensitive to abiotic stresses. Subcellular localization in pineapple protoplasts, tobacco leaves and <i>Arabidopsis</i> roots showed that all the seven pineapple YABBY proteins were nucleus localized. Overexpression of <i>AcYABBY4</i> in <i>Arabidopsis</i> resulted in short root under NaCl treatment, indicating a negative regulatory role of <i>AcYABBY4</i> in plant resistance to salt stress. This study provides valuable information for the classification of pineapple <i>AcYABBY</i> genes and established a basis for further research on the functions of AcYABBY proteins in plant development and environmental stress response.