Isolation and Characterization of the Sulfate Transporter Gene Family and Its Expression Pattern in Response to Selenium and Abiotic Stress in Walnuts (Juglans regia L.)

Abstract

The sulfate transporter (SULTR) is responsible for the transport and uptake of sulfate, which plays an indispensable role in the growth cycle of plants and adaptation to plant stress. However, there are few reports on the response and regulation of SULTR gene family members in walnuts (Juglans regia L.) to sodium selenate, low temperatures, high temperatures, and simulated drought stress. In this study, the whole genome of the SULTR genes family in walnuts was identified and analyzed by the bioinformatics method. The results show that the walnut genome contains seventeen JrSULTR genes, which are unevenly distributed on eight chromosomes and can be divided into four subfamilies. Cis-acting elements that respond to stress and participate in the regulation of plant hormones were found in the promoter sequence of the JrSULTR genes. The analysis of transcriptome data showed that the expression of JrSULTR1.2b was significantly upregulated under sodium selenate treatment, and the results of qRT-PCR analysis were basically consistent with the transcriptome data. The expression of JrSULTR3.1a and JrSULTR3.4b increased with the prolongation of simulated drought stress time. The transcription levels of JrSULTR1.2b and JrSULTR3.1a were significantly increased after low-temperature treatment. After 9 h of high-temperature treatment, the expression levels of JrSULTR3.1a and JrSULTR3.3 were significantly increased. JrSULTR1.2b and JrSULTR3.1a showed significant expression specificity under stress treatment. At the same time, we also performed subcellular localization of these two genes, which was consistent with the predicted results and was in the cell membrane, and their regulatory functions need to be further studied. These studies laid the foundation for us to explore the specific function of the JrSULTR genes in alleviating abiotic stress in walnuts.