Identification and Expression Analysis of the <i>SWEET</i> Gene Family from <i>Poa pratensis</i> Under Abiotic Stresses

Abstract

The sugars will eventually be exported transporters (SWEET) gene family is a glycoprotein gene family that can regulate the transport of sugar in plants and plays an important role in plant growth and development, as well as in response to environmental stress. In this study, Kentucky bluegrass (cv. Baron) seedlings were grown in various treatments, including heavy metal cadmium, salt, drought, cold, and heat stress for 6 h, 24 h, 48 h, and 7 day. The relative expression of the identified <i>PpSWEET</i> genes in Kentucky bluegrass was measured. The results showed there were a total of 13 <i>SWEET</i> genes, which could be divided into four clades by phylogenetic analysis. Most <i>PpSWEET</i> genes are alkali proteins with seven transmembrane helices. Moreover, almost all PpSWEET proteins possess similar conserved motifs and active sites. In addition, an analysis of the relative expression of <i>PpSWEET</i> genes under various stress treatments indicated that <i>PpSWEET12</i> and <i>PpSWEET15</i> had very high expression under the five types of stress, meaning they can be used as important candidate genes for studying responses to environmental stresses of turfgrass. Furthermore, certain genes only showed changes in expression under one or two specific stress treatments. This study provides important insight into the SWEET gene family in Kentucky bluegrass and its functional roles in responses to various environmental stresses.