Abstract
BackgroundSoybean is a major source of oil and protein in the human diet and in animal feed. However, as soybean is deficient in sulfur-containing amino acids, its nutritional value is limited. Increasing sulfate assimilation and utilization efficiency is a valuable approach to augment the concentration of sulfur-containing amino acids in soybean seeds, and sulfate transporters play important roles in both sulfate uptake and translocation within plants.ResultsIn this study, we isolated and characterized a soybean sulfate transporter gene: GmSULTR1;2b. The gene was found to be specifically expressed in root tissues and induced by low-sulfur stress. In addition, GmSULTR1;2b expression in yeast could complement deficiency in the sulfate transporter genes SUL1 and SUL2. Under +S conditions, GmSULTR1;2b-overexpressing tobacco plants accumulated higher levels of organic matter and exhibited enhanced biomass and seed weight compared to control plants. Under -S conditions, acclimation of GmSULTR1;2b-overexpressing plants was much better than control plants. GmSULTR1;2b-overexpressing tobacco seedlings showed better tolerance to drought stress than the control plants, but no significant difference was observed under salt stress. Transcriptome analysis revealed 515 genes with at least a 2-fold change in expression in the leaves of tobacco plants overexpressing GmSULTR1;2b. Of these, 227 gene annotations were classified into 12 functional categories associated with 123 relevant pathways, including biosynthesis and metabolism-related proteins, stress-related proteins, and transporters.ConclusionsThe findings reported here indicate that the increased biomass and seed yield observed in transgenic tobacco plants could have resulted from greater nutrient uptake and transport capability as well as enhanced development and accumulation of organic matter. Taken together, our results indicate that GmSULTR1;2b plays an important role in sulfur uptake and could alter the sulfur status of plants. Our study suggests that overexpressing GmSULTR1;2b may enhance plant yield under +S conditions, reduce plant production loss under -S conditions, and improve plant tolerance to sulfur deficiency stress.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2705-3) contains supplementary material, which is available to authorized users.
Highlights
Soybean is a major source of oil and protein in the human diet and in animal feed
Identification and phylogenetic and expression analyses of plant sulfate transporter (SULTR) genes Twelve Arabidopsis SULTRs were used as query sequences for BLASTN searches of the soybean database in Phytozome with default parameters; redundant sequences were manually discarded
To gain insight into the biological functions of these genes, a phylogenetic tree was constructed based on a full-length amino acid alignment of the SULTRs (Fig. 1 and Additional file 1: Table S2), including 28 putative soybean SULTR sequences, 12 Arabidopsis thaliana SULTR sequences, 12 Oryza sativa SULTR sequences, and 16 Populus tremula × P. alba SULTR sequences
Summary
As soybean is deficient in sulfur-containing amino acids, its nutritional value is limited. Increasing sulfate assimilation and utilization efficiency is a valuable approach to augment the concentration of sulfur-containing amino acids in soybean seeds, and sulfate transporters play important roles in both sulfate uptake and translocation within plants. As soybean is deficient in sulfur-containing amino acids (methionine, cystine and cysteine), its nutritional value is limited. Marsolais et al [1] reported that major seed storage proteins deficiency was associated with a. For these reasons, the mining and characterization of genes that could genetically alter sulfate assimilation and utilization efficiency is an important approach for increasing the amount of sulfurcontaining amino acids in soybean seeds. Various sulfate transporters with different affinities, capacities and cell typespecific localizations are encoded by a family of genes, and these transporters are responsible for both the absorption of sulfate and its accumulation within cells [5,6,7]
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