Late-Season Nitrogen Applications Increase Soybean Yield and Seed Protein Concentration

Low seed and meal protein concentration in modern high-yielding soybean [Glycine max L. (Merr.)] cultivars is a major concern but there is limited information on effective cultural practices to address this issue. In the objective of dealing with this problem, this study conducted field experiments in 2019 and 2020 to evaluate the response of seed and meal protein concentrations to the interactive effects of late-season inputs [control, a liquid Bradyrhizobium japonicum inoculation at R3, and 202 kg ha−1 nitrogen (N) fertilizer applied after R5], previous cover crop (fallow or cereal cover crop with residue removed), and short- and full-season maturity group cultivars at three U.S. locations (Fayetteville, Arkansas; Lexington, Kentucky; and St. Paul, Minnesota). The results showed that cover crops had a negative effect on yield in two out of six site-years and decreased seed protein concentration by 8.2 mg g−1 on average in Minnesota. Inoculant applications at R3 did not affect seed protein concentration or yield. The applications of N fertilizer after R5 increased seed protein concentration by 6 to 15 mg g−1, and increased yield in Arkansas by 13% and in Minnesota by 11% relative to the unfertilized control. This study showed that late-season N applications can be an effective cultural practice to increase soybean meal protein concentration in modern high-yielding cultivars above the minimum threshold required by the industry. New research is necessary to investigate sustainable management practices that increase N availability to soybeans late in the season

Electrostatic Effects in the Folding of the SH3 Domain of the c-Src Tyrosine Kinase: pH-Dependence in 3D-Domain Swapping and Amyloid Formation

The SH3 domain of the c-Src tyrosine kinase (c-Src-SH3) aggregates to form intertwined dimers and amyloid fibrils at mild acid pHs. In this work, we show that a single mutation of residue Gln128 of this SH3 domain has a significant effect on: (i) its thermal stability; and (ii) its propensity to form amyloid fibrils. The Gln128Glu mutant forms amyloid fibrils at neutral pH but not at mild acid pH, while Gln128Lys and Gln128Arg mutants do not form these aggregates under any of the conditions assayed. We have also solved the crystallographic structures of the wild-type (WT) and Gln128Glu, Gln128Lys and Gln128Arg mutants from crystals obtained at different pHs. At pH 5.0, crystals belong to the hexagonal space group P6522 and the asymmetric unit is formed by one chain of the protomer of the c-Src-SH3 domain in an open conformation. At pH 7.0, crystals belong to the orthorhombic space group P212121, with two molecules at the asymmetric unit showing the characteristic fold of the SH3 domain. Analysis of these crystallographic structures shows that the residue at position 128 is connected to Glu106 at the diverging β-turn through a cluster of water molecules. Changes in this hydrogen-bond network lead to the displacement of the c-Src-SH3 distal loop, resulting also in conformational changes of Leu100 that might be related to the binding of proline rich motifs. Our findings show that electrostatic interactions and solvation of residues close to the folding nucleation site of the c-Src-SH3 domain might play an important role during the folding reaction and the amyloid fibril formation.This research was funded by the Spanish Ministry of Science and Innovation and Ministry of Economy and Competitiveness and FEDER (EU): BIO2009-13261-C02-01/02 (ACA); BIO2012-39922-C02-01/02 (ACA); CTQ2013-4493 (JLN) and CSD2008-00005 (JLN); Andalusian Regional Government (Spain) and FEDER (EU): P09-CVI-5063 (ACA); and Valentian Regional Government (Spain) and FEDER (EU): Prometeo 2013/018 (JLN). Data collection was supported by European Synchrotron Radiation Facility (ESRF), Grenoble, France: BAG proposals MX-1406 (ACA) and MX-1541 (ACA); and ALBA (Barcelona, Spain) proposals 2012010072 (ACA) and 2012100378 (ACA)

Diversifying Soybean Production Risk Using Maturity Group and Planting Date

Due to the long growing season for soybean production, producers in the Mid-southern US can plant from late March to June. They also have a range of maturity group (MG) choices, affecting the length of the growing season, that are physiologically and economically viable. A producer’s decision of what to plant and when constitutes two potential decision variables that can be freely manipulated to not only maximize profit, but also reduce economic risk. Early maturing MG III and IV soybean cultivars planted early or mid-season typically are highest yielding and thereby the preferred choice of producers. However, planting part of a producer’s acreage at later dates and using later maturing MG VI soybeans may offer producers similar returns (as observed with early planting using early maturing cultivars) at a meaningfully reduced level of risk

Overall fold of the monomeric structure of the c-Src-SH3 domain.

<p>Overall fold of the monomeric species of the WT c-Src-SH3 domain (WT_M, PDB code 4JZ4). The AU is composed by two chains of the SH3 domain; both chains are represented as a cartoon (white). The n-Src loop residues in chains A and B are shown in red. In chain B, the poor electronic density in the difference maps does not allow to model residues 114-115. Both chains show a nickel-binding site at the N-terminal formed by the residues His83-Ser82-Gly81, with slight differences in the conformation and in the axial ligand (nickel ion is represented with a green sphere). All the figures were performed using the program Pymol 1.7 (distributed by Schrödinger).</p

Superposition of the monomeric structures of the c-Src-SH3 domain.

<p>Superposition of the crystallographic structures of the monomeric c-Src-SH3 domain (WT_M, chain A blue and B clear blue, PDB code 4JZ4; Q128E_M, chain A red and B clear red, PDB code 4OMO) with that solved by NMR (PDB code 1SRL) (grey).</p

Intertwined dimer structures of the c-Src-SH3 domain.

<p>(A) Structure of the intertwined dimer of the c-Src-SH3 domain. Open chain of the WT c-Src-SH3 domain is shown in cartoon (blue). Chain B, which generates the dimer, was obtained by symmetry (light-blue). (B) Superposition of the intertwined structures of the WT_D (blue) and Q128E_D (red), Q128K_D (yellow), Q128R_D (green) mutants. (C) Superposition of the open chain of the intertwined dimer structure of the WT c-Src-SH3 domain (blue) (PDB code 4JZ3) to chain A of the monomeric structure of the WT (PDB code 4JZ4): the overlay of the N- and C-terminal regions is shown in cyan and white, respectively.</p

Nucleation site of the WT c-Src SH3 domain.

<p>Hydrogen-bond interactions among the residues belonging to the diverging β-turn and those of the distal loop are shown in green dotted lines. WT_M (PDB code 4JZ4) chains A (panel A) and B (panel B) are shown in blue and cyan, respectively. (C) Intertwined dimer structure of the WT c-Src SH3 domain (PDB code 4JZ3), residues at chain A are shown in white sticks and those belonging to the symmetry related molecule (chain B) are in magenta sticks.</p

Comparisons in terms of RMSD (Å).

a<p>Alignment performed taking into account only non-hydrogen atoms.</p>b<p>Alignment performed taking as reference residues 84-110 of the monomer.</p>c<p>Alignment performed taking as reference residues 117-140 of the monomer.</p><p>Comparisons in terms of RMSD (Å).</p

Hydrogen-bond distances in the water network at the distal loop and diverging β-turn.

<p>Hydrogen-bond distances in the water network at the distal loop and diverging β-turn.</p

DLS experiments.

<p>(A) Average <i>R</i>_h as a function of c-Src-SH3 domain concentration, in 0.1 M sodium acetate (pH 5.0) at 25°C. Symbols represent measured data in the presence of 5% PEG300 (open circles) and absence of PEG300 (filled circles). (B) Aggregation kinetics of c-Src-SH3 followed by DLS. The protein at a concentration of 25 mg·ml⁻¹ (3.6 mM) in 0.1 M sodium acetate pH 5.0 was incubated at 25°C (square) containing 5% PEG300 and without PEG300 at 20°C (triangles) and 25°C (circles) as a function of time.</p