Identification and prediction of functions for drought-responsive genes in sugar beet (Beta vulgaris L.)

Drought is an environmental stress factor restricting the growth and productivity of plants. Sugar beet can acclimate to diverse types of abiotic stress, such as drought. Although many studies on response of sugar beet to drought stress have been conducted, the expressions of drought-responsive genes in sugar beet have rarely been comprehensively investigated. In this study, we performed a transcriptome analysis of leaf samples from water-controlled sugar beet seedlings. The clean reads were obtained and assembled into 21,749 unique genes. Among them, we identified 1,675 differentially expressed genes (DEGs). According to the findings of the Gene ontology (GO) analysis, "biological process", "metabolic process", "oxidation-reduction process" and "catalytic activity" were the most highly enriched GO terms. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that "biosynthesis of secondary metabolites", "metabolic pathways", "plant hormone signal transduction", and "protein processing in endoplasmic reticulum" were the four most highly enriched pathways. Drought stress significantly restrained dry mass and net photosynthetic rate of sugar beet. The expression levels of genes encoding homeobox-leucine zipper protein ATHB-12, berberine bridge enzyme-like 13, auxin response factor 5, and photosystem I subunit O were significantly altered under drought stress. In addition, 36 DEGs occurred with differential alternative splicing. Our findings provided new insights into the regulatory functions of genes related to drought resistance in sugar beet.