Genome-Wide Identification of the A20/AN1 Zinc Finger Protein Family Genes in Ipomoea batatas and Its Two Relatives and Function Analysis of IbSAP16 in Salinity Tolerance

Abstract

Stress-associated protein (SAP) genes-encoding A20/AN1 zinc-finger domain-containing proteins-play pivotal roles in regulating stress responses, growth, and development in plants. They are considered suitable candidates to improve abiotic stress tolerance in plants. However, the <i>SAP</i> gene family in sweetpotato (<i>Ipomoea batatas</i>) and its relatives is yet to be investigated. In this study, 20 <i>SAPs</i> in sweetpotato, and 23 and 26 <i>SAPs</i> in its wild diploid relatives <i>Ipomoea triloba</i> and <i>Ipomoea trifida</i> were identified. The chromosome locations, gene structures, protein physiological properties, conserved domains, and phylogenetic relationships of these <i>SAPs</i> were analyzed systematically. Binding motif analysis of <i>IbSAPs</i> indicated that hormone and stress responsive <i>cis</i>-acting elements were distributed in their promoters. RT-qPCR or RNA-seq data revealed that the expression patterns of <i>IbSAP</i>, <i>ItbSAP</i>, and <i>ItfSAP</i> genes varied in different organs and responded to salinity, drought, or ABA (abscisic acid) treatments differently. Moreover, we found that <i>IbSAP16</i> driven by the <i>35 S</i> promoter conferred salinity tolerance in transgenic <i>Arabidopsis</i>. These results provided a genome-wide characterization of <i>SAP</i> genes in sweetpotato and its two relatives and suggested that <i>IbSAP16</i> is involved in salinity stress responses. Our research laid the groundwork for studying SAP-mediated stress response mechanisms in sweetpotato.