Varying Response of the Concentration and Yield of Soybean Seed Mineral Elements, Carbohydrates, Organic Acids, Amino Acids, Protein, and Oil to Phosphorus Starvation and CO2 Enrichment

Abstract

A detailed investigation of the concentration (e.g., mg g-1 seed) and total yield (e.g., g plant-1) of seed mineral elements and metabolic profile under phosphorus (P) starvation at ambient (aCO2) and elevated carbon dioxide (eCO2) in soybean is limited. Soybean plants were grown in a controlled environment at either sufficient (0.50 mM P, control) or deficient (0.10 and 0.01 mM, P-stress) levels of P under aCO2 and eCO2 (400 and 800 μmol mol-1, respectively). Both the concentration and yield of 36 out of 38 seed components responded to P treatment and on average 25 and 11 components increased and decreased, respectively, in response to P starvation. Concentrations of carbohydrates (e.g., glucose, sugar alcohols), organic acids (e.g., succinate, glycerate) and amino acids increased while oil, and several minerals declined under P deficiency. However, the yield of the majority of seed components declined except several amino acids (e.g., phenylalanine, serine) under P deficiency. The concentration-based relationship between seed protein and oil was negative (r2 = 0.96), whereas yield-based relationship was positive (r2 = 0.99) across treatments. The CO2 treatment also altered the concentration of 28 out of 38 seed components, of which 23 showed decreasing (e.g., sucrose, glucose, citrate, aconitate, several minerals, and amino acids) while C, iron, Mn, glycerate, and oil showed increasing trends at eCO2. Despite a decreased concentration, yields of the majority of seed components were increased in response to eCO2, which was attributable to the increased seed production especially near sufficient P nutrition. The P × CO2 interactions for the concentration of amino acids and the yield of several components were due to the lack of their response to eCO2 under control or the severe P starvation, respectively. Thus, P deficiency primarily reduced the concentration of oil and mineral elements but enhanced a majority of other components. However, seed components yield consistently declined under P starvation except for several amino acids. The study highlighted a P nutritional-status dependent response of soybean seed components to eCO2 suggesting the requirement of an adequate P supply to obtain the beneficial effects of eCO2 on the overall yield of various seed components.

Characterization of Select Wild Soybean Accessions in the USDA Germplasm Collection for Seed Composition and Agronomic Traits

“…The exceptions were the traits whose heritability estimates were <0.50, including seed contents of glucose, fructose, valine, and proline. Grieshop and Fahey (2001) and Karr-Lilienthal et al (2005) suggested that differences in temperature among studied environments may contribute to variation in amino acid content, and Singh et al (2016) stated that the free amino acid increased when there was a deficit of phosphate, and the seed amino acid decreased under elevated CO 2 conditions. The heritability estimates for amino acids on an entrymean basis for Set 2 were relatively high, with a range of 0.30 to 0.84 (Table 2).…”

“…The highest average content of 6 of the 12 amino acids was observed in 15NOV. Grieshop and Fahey (2001) and Karr-Lilienthal et al (2005) suggested that differences in temperature among studied environments may contribute to variation in amino acid content, and Singh et al (2016) stated that the free amino acid increased when there was a deficit of phosphate, and the seed amino acid decreased under elevated CO 2 conditions. To our knowledge, the results of this study are some of the first published and publicly available amino acid data sets in wild soybean seed grown across multiple replications and environments.…”

Increased temperatures may safeguard the nutritional quality of crops under future elevated CO2 concentrations

“…Furthermore, dilution by enhanced carbohydrate production at eCO 2 or dilution by increased seed production could contribute to the reduced mineral concentrations observed. Dilution by enhanced carbohydrate production cannot explain all of the effects of eCO 2 (McGrath and Lobell, ), but the impact of changes in seed yield on the content of minerals on a plant basis (Singh et al ., ) has not been broadly considered. However, it is reasonable to assume that if a micronutrient is obtained in controlled or limited amounts it would be diluted when distributed amongst a greater number of seeds produced at eCO 2 , such that the concentration would decrease while the mineral seed content per plant would not change.…”

Potassium Deficiency Influences Soybean Seed Mineral Compositions and Metabolic Profiles across CO&lt;sub&gt;2&lt;/sub&gt;

“…However, the response of seed metabolic profiles under different K fertilization regimes have been found vary under field conditions [12] [13] [14], especially due to the interactions with other existing factors such as temperature and soil moisture contents in fields [2] [12] [13] [14]. In the controlled environment conditions, we have reported that the deficiency of a given mineral nutrients including K and phosphorus (P) leads to the alteration in the concentration of several other minerals elements and seed constituents in plant and seed tissues [10] [11] [27]. In the previous report, we found that under K deficiency the depressed soybean productivity was primarily associated with the decreased growth traits such as plant size and total leaf area than the photosynthetic processes across CO 2 levels [11].…”