Genome-Wide Identification of Soybean ABC Transporters Relate to Aluminum Toxicity

Abstract

ATP-binding cassette (ABC) transporter proteins are a gene super-family in plants and play vital roles in growth, development, and response to abiotic and biotic stresses. The ABC transporters have been identified in crop plants such as rice and buckwheat, but little is known about them in soybean. Soybean is an important oil crop and is one of the five major crops in the world. In this study, 255 <i>ABC</i> genes that putatively encode ABC transporters were identified from soybean through bioinformatics and then categorized into eight subfamilies, including 7 <i>ABCAs</i>, 52 <i>ABCBs</i>, 48 <i>ABCCs</i>, 5 <i>ABCDs</i>, 1 <i>ABCEs</i>, 10 <i>ABCFs</i>, 111 <i>ABCGs</i>, and 21 <i>ABCIs</i>. Their phylogenetic relationships, gene structure, and gene expression profiles were characterized. Segmental duplication was the main reason for the expansion of the <i>GmABC</i> genes. Ka/Ks analysis suggested that intense purifying selection was accompanied by the evolution of GmABC genes. The genome-wide collinearity of soybean with other species showed that GmABCs were relatively conserved and that collinear ABCs between species may have originated from the same ancestor. Gene expression analysis of <i>GmABCs</i> revealed the distinct expression pattern in different tissues and diverse developmental stages. The candidate genes <i>GmABCB23</i>, <i>GmABCB25</i>, <i>GmABCB48</i>, <i>GmABCB52</i>, <i>GmABCI1</i>, <i>GmABCI5</i>, and <i>GmABCI13</i> were responsive to Al toxicity. This work on the <i>GmABC</i> gene family provides useful information for future studies on ABC transporters in soybean and potential targets for the cultivation of new germplasm resources of aluminum-tolerant soybean.