Induction of citrate transporter gene expression in soybean roots by sulfur application

The Application of Sulfur Influences Microbiome of Soybean Rhizosphere and Nutrient-Mobilizing Bacteria in Andosol

“…The test soil used in the current study was Andosol, which is commonly characterized as possessing an abundance of active Al and Fe [ 56 ]; thus, the dominant form of P might be bound to Al or Fe considering the high P adsorption capacity of the soil. Aside from the P form, the citric acid excreted from the roots may have high efficiency in solubilizing P with S treatment [ 11 , 12 ]. In the present study, the citric acid excreted from S-applied soybean was likely higher but not considerable as compared to the NS-applied soybean.…”

“…Then, the P content in the filtrate was determined by colorimetric analysis using the molybdenum sulfate method [ 30 ]. In addition to the S and P content [ 12 ], total carbon (C) and total nitrogen (N) were quantified with the dry combustion method using an NC analyzer (SUMIGRAPH NC TR22, Sumika Chemical Analysis Service, Ltd., Osaka, Japan) with glutamic acid as standard sample. Acid oxalate extractable Fe and aluminum (Al), which contain active Fe and Al oxides, aluminosilicates, and organically bound Fe and Al, were extracted using acidic ammonium oxalate solution (0.2M, pH 3.0) [ 31 ].…”

“…The lyophilized samples were redissolved with 2 mL milli-Q water and filter sterilized with a 0.22 µm membrane (Millex ® -GV, Millipore, Cork, Ireland). The organic acids were analyzed using a high-performance liquid chromatography system equipped with Shim-pack column SCR102H and RSpack KC-811 (Shimadzu Co., Kyoto, Japan) at a column temperature of 40 °C, and the UV detector SPD-20A (Shimadzu Co., Kyoto, Japan) at 210 nm [ 12 ]. Moreover, the mobile phase used was 0.1% H 3 PO 4 with a flow rate of 0.5 mL min −1 and measurement time of 50 min.…”

“…On the other hand, S application in soybean promotes organic acid production and increased phosphorus (P) availability in the rhizosphere [ 11 ]. It has also been observed that S fertilization may be involved in the induction of a citric acid transporter gene, GmMATE13 , contributing to the excretion of the said organic acid in soybean roots [ 12 ]. Application of S in soybean may have significance on the P solubilization in the rhizosphere through augmentation of the organic acids produced in the roots.…”