Genome-Wide Identification and Expression Analysis of Sucrose Transporter Gene Family in Wheat Lines under Heat Stress

Abstract

Sucrose transporters (SUTs) play vital roles in phloem sucrose unloading and transportation in wheat grains. However, the genomic information regarding the SUT gene family and their expression patterns in response to heat stress in grains of male-sterile wheat (Triticum aestivum L.) lines has not been systematically studied. In this study, a thorough examination of the wheat SUT gene family was conducted, focusing on their expression patterns in male-sterile lines under heat stress conditions in grain tissues. A total of 19 SUT genes were identified, with phylogenetic analysis indicating their classification into five distinct groups. Polyploidization was identified as a substantial factor in the expansion of SUT genes, with segmental duplication being the predominant mechanism driving the evolutionary expansion of the SUT gene family in wheat. Transcriptome data indicate that the expression levels of TaSUT1 and TaSUT2 were higher than other SUT genes in grains of male-sterile lines. The TaSUT1 expression showed a gradual decreasing trend, while TaSUT2 showed a reverse trend with the process of grain filling. After heat stress, the TaSUT1 expression in grains of male-sterile lines was first significantly increased and then significantly decreased with the filling stage extension, aligning with the observed trend of sucrose levels, indicating that heat stress may decrease the grain weight by reducing sucrose unloading and transportation process in grains. These results provide a systematic analysis of the SUT gene family and lay a theoretical foundation for us to study the grain filling of male-sterile lines in response to abiotic stress.