Table 1.
Members of Pi transporter genes in the Pht1 family from soybean.
Figure 1.
Phylogenetic tree of soybean, Arabidopsis, rice and Medicago plant Pi transporter proteins in Pht1 family.
Transporters and corresponding plant species are as follows: rice (Oryza sativa), OsPT1 through OsPT13 [16]; Arabidopsis (Arabidopsis thaliana), AtPht1;1 through AtPht1;9 [14]; Medicago (Medicago truncatula) MtPT1 through MtPT6 [68] and other four PT proteins obtained in Phytozome (http://www.phytozome.net/medicago), soybean (Glycine Max), GmPT1 through GmPT14 (this work).
Figure 2.
Complementation of a yeast inorganic phosphate (Pi) transport mutant by GmPTs genes.
Yeast MB192 cells harboring either an empty expression vector (control) or the candidate Pht1 ORF(open reading frame), transformants were grown in YNB medium to an OD600 ≈0.8, then washed by 3% glucose with centrifugation at 1500 g, 4°C, and suspended in phosphate free YNB medium to OD600 ≈1.0. Different number cells (5×105, 5×104, 5×103) were applied to Pi-limiting medium (20 µM, pH 6.0) then incubated at 30°C for 3 d.
Table 2.
Kinetic parameter estimates of GmPTs-mediated inorganic phosphate (Pi) transport.
Figure 3.
Kinetic analysis of inorganic phosphate (Pi) uptake in yeast.
The non-linear regression of total Pi uptake by strain Yp112-GmPTs versus external Pi concentration at pH 6 were used to estimate the apparent Km value for Pi uptake. All the results were calculated from the three independent experiments.
Figure 4.
Spatial Expression pattern analysis for the 14 GmPTs as related to P availability.
Plants were grown on low P (added 5 µM P as KH2PO4, open bars) and high P (added 500 µM P as KH2PO4, closed bars) conditions. Young leaves (YL), roots (R), stems (S) and flowers (F) were sampled 18 days after treatment initiation, and young pods (P) and seeds (SE) were sampled 29 days after treatment initiation. Each bar is the mean of three biological replications with standard error. Note: different scales are used in the graphs; asterisks indicate significant differences of GmPTs expression in certain tissues under low P and high P conditions in t-tests.
Figure 5.
Expression of P, N, K or Fe responsive genes to different nutrient stresses.
14-day old soybean seedlings were treated with N (−N), K (−K) and Fe (−Fe) deficiencies (see Experimental procedures for details). Seedlings grown under normal solution were used as controls (CK, added 500 µM P as KH2PO4). The expression levels in shoots and roots were analyzed by quantitative real-time PCR. Soybean gene PLDZ (Glyma20g38200) was used as low P responsive gene (A), NiR (Glyma02g14910) for low N treatment (B), HAK (Glyma3g42480) for low potassium treatment (C) and IRT (Glyma07g34930) for low Fe treatment (D), respectively. Each bar was the mean of three biological replications with standard error.
Figure 6.
Responses of GmPTs to different nutrient stresses.
Ten-day old soybean seedlings were treated with N (−N), K (−K) and Fe (−Fe) deficiencies (see Experimental procedures for details). Seedlings grown under normal solution were used as controls (CK, added 500 µM P as KH2PO4). Asterisks indicated the significant differences of GmPTs expression between nutrients deficient stresses and normal conditions in Student’s t-tests.