Selenium increases photosynthetic pigments, antioxidant metabolism, flavonoid biosynthesis, nodulation, and development of soybean plants (Glycine max L.)

doi:10.21203/rs.3.rs-1968995/v1

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Selenium increases photosynthetic pigments, antioxidant metabolism, flavonoid biosynthesis, nodulation, and development of soybean plants (Glycine max L.)

https://doi.org/10.21203/rs.3.rs-1968995/v1

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Purpose

This study aimed to investigate the physiological roles of Se in the photosynthetic pigment profile, oxidative metabolism, flavonoid biosynthesis, nodulation, and its role in soybean production.

Methods

Two independent experiments were carried out: one conducted in soil and the other in a nutrient solution. When the plants reached the V₂ growth stage, five (0, 7.5, 15, 30, and 45 µg kg^− 1) and four Se (0, 5, 10, and 15 µmol L^− 1) rates from a sodium selenate source were applied to soil and hydroponics-based experiments, respectively.

Results

The concentration of photosynthetic pigments, the activity of antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase), and the concentration of total sugars in soybean leaves increased in response to Se fertilization. In addition, Se improves nitrogen assimilation efficiency by increasing nitrate reductase activity, resulting in higher ureides, amino acids, and proteins concentration. Se increases the synthesis of daidzein and genistein in the root, resulting in a greater number of nodules and concentration and transport of ureides to the leaves. Se-treated plants showed greater growth and biomass accumulation in roots.

Conclusion

This research is the first report on the influence of Se on nodulation and flavonoid synthesis in leguminous plants. In the scenario of climate change and the increase of abiotic stresses in agriculture, our results contribute to increasing knowledge about the effects of Se on physiology, biochemistry, and biological nitrogen fixation in legume plants.

Ascorbate peroxidase

catalase

chlorophyll

daidzein

genistein

superoxide dismutase

total sugar

yield.

Selenium (Se) is an essential element for humans and animals and a beneficial element for plants, however the average Se content in most soils is low (0.01–2 mg kg^− 1) (Fordyce 2013). The low availability of Se in arable soils can result in the production of foods with low nutritional Se content. Selenium deficiency in humans is related to pregnancy complications, heart disease, decreased levels of amino acids, and increased risk of mortality from COVID-19 (Oropeza-Moe et al. 2015; Yim et al. 2019; Hofstee et. 2020; Moghaddam et al. 2020).

One of the ways to increase the concentration of Se in the edible parts of plants is through agronomic biofortification by applying fertilizers containing Se in its formulation. (Lanza and Reis 2021). Application of Se at low doses can increase photosynthetic pigments, sugars, nitrate reductase, and antioxidant enzymes and decrease the production of reactive oxygen species (ROS) (Lanza and Reis 2021). Plants fertilized with Se have greater tolerance to abiotic and biotic stress. On the other hand, Se application at high concentration cause phytotoxicity (Lanza et al. 2021). Therefore, further studies are needed to establish optimal doses and sources of Se to avoid detrimental effects.

Soybean (Glycine max L.) is an important crop for human food, so biofortifying soybeans with Se is a good strategy to improve human health. In addition, this plant species perform biological nitrogen fixation with bacteria of the genus Rhizobium. Within this context, the isoflavonoids genistein and daidzein play a crucial role in the expression of nod genes in bacteria, which leads to the synthesis and secretion of nodulation factors that promote a series of physiological changes in plant cells that initiate the formation of nodules in plant roots (Bossi et al. 2021). Inside the nodules, ammonia is converted into ureides (allantoin and allantoic acid) which are transported to the shoot by the xylem sap. Once in the cytosol of cells, ureides are transformed into ammonium, ammonium acids, and proteins that can be used for chlorophyll production, photosynthetic processes, and plant growth (Baral et al. 2016).

Selenium can affect nodulation, biological nitrogen fixation, and antioxidant metabolism of soybean plants, however, this has not been deeply investigated. This study hypothesizes that Se affects flavonoid metabolism by increasing nodulation, ureide concentration, and soybean plant yield. This study aimed to investigate the physiological roles of Se in the photosynthetic pigment profile, oxidative metabolism, flavonoid biosynthesis, nodulation, and its relationship with soybean production.

Experimental Site and Soil Preparation

To test our hypothesis, two independent experiments were carried out: one conducted in soil and the other in a nutrient solution. The cultivations were carried out in a greenhouse at the College of Sciences and Engineering of the São Paulo State University, Tupã municipality, Brazil following a completely randomized experimental design.

For analysis of chemical characteristics, 20 soil subsamples from the first 20 cm depth were collected in the experimental area, the material was homogenized, and the following chemical characteristics were determined following Silva et al. (2019) showing chemical characteristics: P mg dm^-3 = 4.0; organic matter mg dm^-3 = 13.0; pH CaCl₂ = 4.6; K mmol_c dm^-3 = 1.4; Ca mmol_c dm^-3 = 4.0; Mg mmol_c dm^-3 = 4.0; H + Al mmol_c dm^-3 = 18.0; Al mmol_c dm^-3 = 3.0; SB mmol_c dm^-3 = 9.4; CTC mmol_c dm^-3 = 27.4; V % = 34.0. For the soil-based experiments, the soil was first collected and prepared using 2.9 g of limestone per each 5 kg soil per pot, 30 days before the sowing to reach 70% base saturation. In addition, each pot received 0.124 g simple superphosphate, 0.25 g potassium chloride, 0.058 g boric acid, 0.083 g copper, and 0.25 g zinc

Readily available soil Se concentration was 3.6 µg kg^-1. To determine Se concentration, 4 g of air-dried soil was added to a 50 mL centrifuge tube along with 20 mL of 0.01 mol L^-1 KNO₃. The solution was shaken in a rotary shaker for 2 h, then centrifuged for 30 min at 1650×g. After centrifugation, 9 mL of the supernatant was pipetted into a < 0.22 µm syringe filter. The supernatant was filtered into a tube containing 10% tetramethylammonium hydroxide (TMAH) and 0.1 mol L^-1 KH₂PO₄ for determination of the readily available Se using inductively coupled plasma-mass spectrometry (ICP-MS; Thermo Fisher Scientific iCAPQ, Thermo Fisher Scientific, Bremen, Germany). Irrigation was performed daily keeping at 80% of soil water retention capacity.

Cultivation

Soybean cultivar BRS 1003 PRO was herein employed. The seeds were treated with pyraclostrobin, thiophanate-methyl, and fipronil, and inoculated with Bradyrhizobium japonicum SEMIA 5079. For the soil-based experiment, eight seeds were sown per pot. After the emergence of seedlings, thinning was performed, and two plants per pot were left. Weed control was carried out manually. Pyrethroid insecticide was used for insect control.

For the hydroponics experiment setup, the seeds were germinated in a sand substrate for 14 days, then transferred to a nutrient solution with a low-N (107 µM) containing 30 µM KNO₃, 24 µM Ca(NO₃)₂·4H₂O, 8 µM NH₄NO₃, 6 µM (NH₄)₂SO₄, 1.2 mM CaCl₂·2H₂O, 300 µM K₂SO₄, 50 µM KH₂PO₄, 1.5 µM MnSO₄·H₂O, 1.5 µM ZnSO₄·7H₂O, 0.5 µM CuSO₄·5H₂O, 0.15 µM (NH₄)₆Mo₇O₂₄·4H₂O, 2.5 µM NaB₄O₇·10H₂O, 40 µM EDTA-Fe, and 0.1 µM CoCl₂·6H₂O, and 50 µM MgCl₂·6H₂O (Peng et al. 2018). After 1 week, plants were transferred into a 1/10 N (531 µM) nutrient solution as described by Peng et al. (2018). The solution was renewed every 5 days, and the pH was adjusted to 6.5 using hydrochloric acid. At each renewal of the solution, 2 mL of inoculant containing Bradyrhizobium japonicum SEMIA 5079 was added for each liter of solution.

Se application

When the plants reached the V₂ growth stage, five Se doses (0, 7.5, 15, 30, and 45 µg kg^-1) in pot experiments and four Se concentrations (0, 5, 10, and 15 µmol L^-1) in hydroponics were applied using sodium selenate (Sigma-Aldrich) as Se source.

A pot experiment was carried out using eight independent biological replications, of which four were used for destructive analysis at flowering, and four were carried out until grains maturation to estimate soybean yield. Hydroponic-based experiments contained four biological replications that were conducted until flowering for nodule investigation and flavonoid analysis.

Quantification of antioxidant metabolism and photosynthetic pigments

At flowering for both experiments, the diagnosis leaves were collected and macerated in liquid nitrogen and stored in a freezer at -80 ºC until processed. Lipid peroxidation was based on malondialdehyde (MDA) concentration as described by Heath and Packer (1968). The concentration of H₂O₂ was performed according to Alexieva et al. (2001). Besides, the material preparation for total proteins determination, as well as SOD (EC:1.15.1.1), CAT (EC:1.11.1.6), and APX (EC:1.11.1.11) activity were performed as described by Gomes-Junior et al. (2007). The quantification of total proteins, SOD, CAT, and APX activity were performed as described by Bradford (1976), Giannopolitis and Ries (1977), Azevedo et al. (1998) and Moldes et al. (2008), respectively. Finally, the photosynthetic pigments quantification was performed at the flowering stage and according to Lichtenthaler (1987).

Determination of N-compounds in leaves and nodules

Leaf and nodule concentration of total sugars, amino acids, nitrate, ammonia, and ureides (allantoin and allantoic acid) was determined. For extraction and determination of total sugar, amino acids, nitrate, ammonia, and ureides, 1 g of fresh tissue was added into 10 mL of MCW solution (60% v/v methanol, 25% v/v chloroform, and 15% v/v H₂O). After 48 h extraction in the refrigerator, 4 mL of the supernatant was collected and 1 mL of chloroform and 1.5 mL of deionized water were added, and the mixture was diverted to another tube. After phase separation, total sugars, amino acids, nitrate, ammonia, and ureides were determined according to DuBois et al. (1956), Yemm and Cocking (1955), Cataldo et al. (1975), McCullough (1967) and Vogels and Van Der Drift (1970), respectively. The total concentrations of sugar, amino acids, nitrate, ammonia, and ureides were based on the standard curve of sucrose, methionine, calcium nitrate tetrahydrate, ammonium sulfate, and allantoin, respectively, and the results were expressed in µmol g^− 1 FW (fresh weight).

Nitrate reductase activity was performed as described by Reis et al. (2009). All measurements herein described were carried out using an ultraviolet-visible spectrophotometer (SP-220, BioespectroTM, Brazil). All quantifications were performed using external standard-based calibration curves.

Determination of flavonoids in roots

To determine the flavonoids, i.e., rutin, genistein, daidzein, kaempferol, and naringenin, roots tissues were splatted from the shoots and dried in an oven with forced air circulation at 60 ºC until constant weight. Thereafter, the roots were macerated, and 0.1 g of material was weighed for each replication and mixed with 2 mL of 70% v/v methanol. Afterward, the samples were exposed for 30 minutes to sonication. Finally, the samples were centrifuged at 5000 rpm for 20 minutes and filtered in vials. Flavonoid readings were performed in a high-performance liquid chromatography (HPLC) system. To determine the results, a standard solution containing known concentrations of daidzein, genistein, kaempferol, rutin, and naringenin was used.

Determination of biometrics and yield components

At grain maturation, the plants were collected, divided into shoots and roots, and placed in an oven with forced air circulation at 60 ºC until constant weight to determine the dry weight of shoots and roots. Furthermore, the plant height, the number of pods, grains, the weight of 100 seeds, and soybean yield per pot were determined.

Statistical analysis

The results were first subjected to the Shapiro-Wilk normality test and after analysis of variance (ANOVA) followed by Tukey’s mean comparison test at p < 0.05. To verify the correlation between the variables, Pearson's correlation was performed. The R software version 4.0.3 was used.

Se enhances photosynthetic pigments and antioxidant metabolism

The soybean leaves at the flowering stage exposed to Se at a dose of 7.5 µg kg^− 1 presented higher chlorophyll B and carotenoids (Fig. 1b and d). The hydroponic-based experiment showed an increase in chlorophyll A, chlorophyll B, total chlorophyll, carotenoids, and pheophytins concentration (A and total) of plants that received fertilization with 5 µmol L^− 1 of Se (Fig. S1a,b,c,d,e, and f).

The soil-based experiment presented increased MDA concentration in plants under 30 and 45 µg kg^− 1 of Se (Fig. 2a), however, there was no influence of Se on MDA concentration in the hydroponic-based experiment (Fig. S2a). The concentration of H₂O₂ was higher in plants that received fertilization with Se at doses of 15 and 30 µg kg^− 1 (Fig. 2b) and 15 µmol L^− 1 (Fig. S2) for soil and hydroponic-based experiments, respectively.

The highest activity of SOD was observed in plants that were exposed to 15 µg kg^− 1 of Se (Fig. 2c), however, the enzyme activity was lower in plants exposed to Se regardless of the dose in the hydroponic-based experiment (Fig. S2c). Plants that received Se regardless of the dose in both experiments presented increased CAT activity compared to the control group (Fig. 2d; Fig. S2d).

Se application at doses of 15, 30, and 45 µg kg^− 1 (Fig. 2e) and 10 µmol L^− 1 (Fig. S2e) for soil and hydroponic-based experiments increased APX activity in soybean leaves, respectively. Higher soluble proteins were detected in plants that were exposed to Se regardless of the dose in both experiments, except for the dose of 15 µg kg^− 1 which presented a lower result than the control (Fig. 2f; Fig. S2f).

Se enhances sugar, N-compounds, and biometric parameters of soybean plants

Nitrate reductase activity was increased in plants that received Se at doses of 15, 30, and 45 µg kg^− 1 and 5 and 10 µmol L^− 1 for soil and hydroponic-based experiments, respectively (Fig S3a and b). Se application at doses of 15, 30 for soil-based experiment and 45 µg kg^− 1 and 15 µmol L^− 1 for hydroponic-based experiment increased total soluble sugar Fig S3c and d).

Curiously, there was no influence of Se on nitrate concentration compared to the control in both experiments (Fig. 3a; Fig. S4a). Se decreased the ammonia concentration at doses of 15, 30, and 45 µg kg^− 1 in the soil-based experiment and did not influence this trait in the hydroponic-based experiment (Fig. 3b; Fig. S4b). On the other hand, the content of the amino acids has increased for both soil and hydroponic cultivation, regardless of the dose of Se applied (Fig. 3c; Fig S4c).

Allantoin concentration significantly differed from the control under 7.5 and 15 µg kg^− 1 and 10 and 15 µmol L^− 1 for soil and hydroponic-based experiments, respectively (Fig. 3d; Fig S4d). Allantoic acid was also increased when Se was applied at doses of 15 µg kg^− 1 and 5 µmol L^− 1 (Fig. 3e; Fig S4e). The highest concentration of ureides was observed in plants under Se application of 15 µg kg^− 1 for soil-based experiment and 10 and 15 µmol L^− 1 for the hydroponic-based experiment (Fig. 3f; Fig. S4f).

Plants exposed to Se at doses of 45 µg kg^− 1 and 5 and 15 µmol L^− 1 presented higher root dry weight (Fig. 4a; Fig S5a). On the other hand, there was no influence of Se application on shoot dry weight for both experiments (Fig. 4b; S5b). Se increased plant height, regardless of the dose applied, in the soil-based experiment (Fig. 4c), however, there was no influence of Se fertilization on plant height in the hydroponic-based experiment (Fig. S5c).

Se increase nodulation, N-compounds in nodules, and isoflavonoid in soybean root, and yield

Se application also influenced isoflavonoid concentration in soybean roots. Se at the dose of 7.5 µg kg^− 1 increased the concentration of rutin in the roots for the soil-based experiment (Fig. S6a) but decreased at the doses of 10 and 15 µmol L^− 1 for the hydroponic-based experiment (Fig S7a). Higher daidzein was detected at 5 µmol L^− 1 compared to untreated plants (Fig S7b). In soil and hydroponic-based experiments, genistein and naringenin production were induced at all Se doses applied, respectively (Fig. S6d; FigS7c). Selenium also increased kaempferol concentration in the hydroponic-based experiment, and the presence of this isoflavonoid was not detected in the soil-based experiment (Fig S7d).

A higher number of modules was recorded in the roots exposed either to 7.5, 15, and 45 µg kg^− 1 in the soil-based experiment, however, a decrease in the mean nodule weight was observed regardless of the dose of Se applied (Fig. 5). On the other hand, Se decreased the number of nodules but increased the mean weight of nodules in the hydroponic-based experiment (Fig. S8).

The lowest concentration of nitrate was observed at the dose of 45 µg kg^− 1, (Fig S9a). On the other hand, the concentration of ammonia was higher in the nodules of plants that were treated with 15 µg kg^− 1 of Se (Fig S9b). Selenium at doses of 7.5 and 15 µg kg^− 1 increased the concentration of amino acids in the nodules (Fig S9c). There was no influence of Se on the allantoin concentration compared to control plants. However, Se decreased allantoic acid, regardless of the applied dose, and ureides at doses of 7.5 and 15 15 µg kg^− 1 compared to the control (Fig. S9d, e and f)

There was no influence of Se on the number of seeds, the weight of 100 grains, and soybean yield (Fig. 6).

Influence of Se on photosynthetic pigments and enzymatic antioxidant system

Chlorophyll A and B, carotenoids, and pheophytins form the antenna complex that is part of the non-enzymatic antioxidant system of plants (Silva et al. 2020). Chlorophyll B and pheophytins are responsible for dissipating excess sunlight energy (Kitajima and Hogan 2003; Klimov 2003) while chlorophyll A plays a role in plant photosynthesis (Stirbet et al. 2018).

Carotenoids protect plants from excessive light (Silva et al. 2020) and prevent the formation of ROS that can destroy the cell membrane causing cell death (Sachdev et al. 2021). Carotenoids can also mitigate the action of ROS and scavenge free radicals (Silva et al. 2020). In this context, our results indicate that soybean plants supplemented with Se (7.5 µg kg^− 1 and 5 µmol L^− 1) have greater tolerance to abiotic stress because they have a higher concentration of chlorophyll B and carotenoids. Lanza et al. (2021) and De Brito Mateus et al. (2021) reported an increase in the concentration of chlorophyll, carotenoids, and pheophytin in cowpea and coffee plants treated with Se, respectively.

The first enzyme that acts in oxidative stress mitigation is SOD, which acts on the dismutation of singlet oxygen into H₂O₂ (Hayyan et al. 2020). Subsequently, H₂O₂ is converted into water and oxygen by the action of CAT and APX (Silva et al. 2020). In this way, our results indicated that Se increased antioxidant capacity and helped soybean plants against oxidative stress by increasing SOD activity (15 µg kg^− 1), CAT (all doses), and APX (15 µg kg^− 1 and 10 µmol L^− 1). Similar results were obtained by Silva et al. (2020) and Lanza et al. (2021) in cowpea plants. In quinoa plants, Khalofah et al. (2021) reported that Se increased photosynthetic pigments, decreased MDA and H₂O_2, and increased SOD, CAT, and APX activity. De Brito Mateus et al. (2021) and Silva et al. (2018) showed an increase in the activity of antioxidant enzymes in coffee and cowpea plants, respectively.

Influence of Se on nitrogen metabolism, the concentration of total sugars, and biometrics of soybean plants

The higher concentration of amino acids in leaves observed in plants that were fertilized with Se may be related to the increase in the activity of the nitrate reductase enzyme. The influence of Se on nitrate reductase activity may be linked to the fact that Se can increase the absorption of molybdenum, which is a cofactor of this enzyme. Nitrate reductase is the first enzyme to act in the process of nitrogen assimilation in plants, being responsible for the reduction of nitrate to nitrite (Karwat et al. 2019). After the reduction of nitrate to nitrite, nitrite is converted to ammonia and later to amino acids (Karwat et al. 2019). Thus, increasing the activity of this enzyme can increase the efficiency of N metabolism (Dos Santos et al. 2017). Within this context, our results indicated that Se (15 µg kg^− 1, 30 µg kg^− 1, 45 µg kg^− 1 and 5 µmol L^− 1, 10 µmol L^− 1) can improve N assimilation efficiency, increasing amino acid and protein synthesis and bioavailability of inorganic compounds for plants.

In a study regarding Se application in lettuce plants, Se increased the efficiency of N metabolism by increasing the activity of enzymes related to the process of assimilation and reduction of nitrogen such as nitrate reductase resulting in higher plant biomass and reduced N concentration in leaves (Rios et al., 2010a; Rios et al., 2010b). In our research, we found that the activity of nitrate reductase showed a positive correlation with the concentration of nitrate, sugars, and amino acids in the leaves (Fig. S10).

Fertilization of plants with Se increased foliar levels of allantoin and allantoic acid. In leaves, ureides are transformed into amino acids and proteins and used for plant growth and development (Baral et al. 2016). In leguminous plants, ureides can represent more than 90% of all transported by the xylem (Raso et al. 2007). In this context, the increase in the ureides production (15 µg kg^− 1, 10 µmol L^− 1, and 15 µmol L^− 1) is important to increase the N transport to the shoot and can be used for the production of photosynthetic pigments since nitrogen is part of the chlorophyll molecule (Tibiletti et al. 2016). In this research, we verified that the concentration of total ureides positively correlated with the concentration of chlorophyll A, total chlorophyll, and pheophytin A (Fig. S10).

The increase in osmolyte compounds such as total soluble sugars may demonstrate a defense mechanism for the osmotic readjustment (Khalofah et al. 2021) of plants helping to mitigate stress. Thus, our results indicated that Se (15, 30, and 45 µg kg^− 1 and 15 µmol L^− 1) influenced the osmotic adjustment of soybean, which can help plants against stress, mainly due to lack of water. An increase in total sugar concentration as a function of Se fertilization has been reported in quinoa (Khalofaf et al. 2021), coffee (De Brito Mateus et al. 2021), rice (Gouveia et al. 2020), and cowpea (Silva et al. 2018).

An increase in the root system of plants can help in water and nutrients uptake, in addition to increasing tolerance to water deficit. Within this context, our results showed that Se (45 µg kg^− 1 and 5 and 15 µmol L^− 1) increases the root system of plants and can assist in the absorption of water and nutrients. Ikram et al. (2020) found an increase in root dry weight in wheat plants that received Se nanoparticles at a dose of 30 mg L^− 1

The increase in the number of nodules, and amino acids in the leaves and the activity of antioxidant enzymes positively influenced the growth and development of the roots of soybean plants (Fig. S10).

Influence of Se on flavonoid synthesis, nodulation, and yield of soybean plants

Se increased daidzein concentration and stimulated genistein production in soybean roots. These isoflavonoids are crucial molecules for nodulation to occur in leguminous plants, being inducers for the expression of nod genes, which are responsible for the production and secretion of compounds known as nodulation factors (Nod Factors) by symbiotic bacteria, which induce a series of modifications. physiological changes in plant cells for the formation of the nodule (Bosse et al. 2021).

Our results indicated that plants under Se application released more flavonoid molecules which resulted in greater nodulation or larger nodules, depending on how the soybean was grown. However, in both experiments, greater ureide biosynthesis was observed.

Selenium also increased the nitrate, ammonia, and amino acids concentration in the nodules. The decrease in ureide content in the nodules of plants that received lower doses of Se may indicate that low doses of Se can stimulate the translocation of total ureides to the shoot via the xylem, where they are catabolized into amino acids and proteins (Baral et al. 2016), or it may also be stimulating the degradation of ureides in the nodules before transporting the xylem, given that ammonia is one of the products of ureide degradation (Duran and Todd 2012), and the ammonia concentration increased in the nodules of plants that received Se at a dose of 15 µg kg^− 1

In this research, Se did not influence soybean yield. Similar results were obtained in rice (Reis et al. 2018) and cowpea (Silva et al. 2019). Although Se can increase crop yield, this effect is more commonly reported in studies in which plants are submitted to stressful conditions: under salt stress conditions, Se can enhance the yield of cowpea (Manaf, 2018) and mungbean (Kaur and Nair, 2015), while wheat under ultraviolet stress presented increased yield under Se application (Yao et al. 2013). Those beneficial Se effects on yield are more common in plants under stress most likely due to Se well know enhancement in oxidative stress mitigation and ROS scavenging systems (Silva et al. 2020; Lanza and Reis 2021). It’s also noteworthy that Se might impair plant yield due to phytotoxicity (Silva et al. 2018), thus the lack of yield response in the present study suggests that the doses used are not detrimental to soybean in the observed conditions.

Se improves nitrogen assimilation efficiency by increasing nitrate reductase activity, resulting in a higher concentration of ureides, amino acids, and proteins. Se increases the synthesis of daidzein and genistein in the root, resulting in a greater number of nodules and concentration and transport of ureides to the leaves. Se-treated plants showed greater growth, and biomass accumulation in roots without presenting any impairment in grain yield.

This research is the first report on the influence of Se on nodulation and flavonoid synthesis in leguminous plants. In the scenario of climate change and the increase of abiotic stresses in agriculture, our results contribute to increasing knowledge about the effects of Se on physiology, biochemistry and biological nitrogen fixation in legume plants.

Data availability The datasets are available from the corresponding author on request

Funding This research was supported by FAPESP (2020/10053-8)

Competing interests The authors declare that they have no conflict of interest

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Selenium increases photosynthetic pigments, antioxidant metabolism, flavonoid biosynthesis, nodulation, and development of soybean plants (Glycine max L.)

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Abstract

Purpose

Methods

Results

Conclusion

Figures

Introduction

Material And Methods

Experimental Site and Soil Preparation

Cultivation

Se application

Quantification of antioxidant metabolism and photosynthetic pigments

Determination of N-compounds in leaves and nodules

Determination of flavonoids in roots

Determination of biometrics and yield components

Statistical analysis

Results

Se enhances photosynthetic pigments and antioxidant metabolism

Se enhances sugar, N-compounds, and biometric parameters of soybean plants

Se increase nodulation, N-compounds in nodules, and isoflavonoid in soybean root, and yield

Discussion

Influence of Se on photosynthetic pigments and enzymatic antioxidant system

Influence of Se on nitrogen metabolism, the concentration of total sugars, and biometrics of soybean plants

Influence of Se on flavonoid synthesis, nodulation, and yield of soybean plants

Conclusions

Declarations

References

Supplementary Files

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