Genome-wide analysis of the FBA gene family in soybean and their expression profile under salt-alkali stress

Abstract

Fructose-1,6-bisphosphate aldolases (FBAs; EC 4.1.2.13) are core enzymes involved in glycolysis, gluconeogenesis, and the Calvin cycle, exerting vital functions in carbon allocation, plant growth and development, as well as the adaptation to abiotic stresses. Although the FBA gene family has been systematically characterized in a variety of plant species, a comprehensive characterization of FBAs in soybean (Glycine max) remains unreported to date, restricting the elucidation of the conserved and legume-specific functions of GmFBA genes in stress adaptation. In the present study, a total of 13 FBA genes, designated as GmFBA1 to GmFBA13, were identified in the soybean genome, which were unevenly distributed across 9 out of the 20 soybean chromosomes. Subcellular localization prediction showed that six GmFBA proteins were localized in the chloroplast, while the remaining seven were distributed in the cytoplasm. Phylogenetic analysis classified these genes into four distinct classes, and members within the same class shared similar gene structural features. Synteny analysis demonstrated that segmental duplication events served as a major driving force for the expansion of the GmFBA gene family. Promoter sequence analysis revealed that the upstream regulatory regions of GmFBA genes contained a variety of cis-acting elements associated with hormone responses and stress tolerance, suggesting that the expression of GmFBA genes might be modulated by diverse developmental cues and environmental stresses. Expression profiling indicated that GmFBA genes displayed differential expression patterns in various organs and tissues of soybean, and a number of GmFBA genes showed significant expression changes under biotic and abiotic stress conditions. Transcriptome analysis revealed distinct expression patterns of GmFBA genes in response to salt-alkali stress. Furthermore, quantitative real-time PCR assays indicated a significant upregulation of two specific GmFBA genes, GmFBA2 and GmFBA11. These findings suggest that GmFBA2 and GmFBA11 may serve as candidate genes potentially involved in the adaptive response to salt-alkali stress. Collectively, this study presents the first comprehensive characterization of the FBA gene family in soybean, puts forward putative candidate genes for salt-alkali tolerance breeding, and lays a foundation for subsequent functional investigations.