Evaluation of Soil S Pools under 23 Years of Maize Monoculture

Sulfur nutrition is a critical part of proper crop growth and development. In our study, biomass yields (BY) and S uptake were investigated on long-term maize monoculture on haplic luvisol soil during the 23 years of this trial, as well as changes in water extractable (Sw), adsorbed (Sads), mineral (Sav), and pseudo-total S (St) fractions. Treatments used in this study are: (1) Control (Cont); (2) ammonium sulfate (AS); (3) urea and ammonium nitrate (UAN); (4) UAN + phosphorus and potassium (UAN + PK); (5) UAN + phosphorus, magnesium, sulfur (UAN + PMgS); and (6) Fallow. Recently, the Mehlich 3 method started to be used in the Czech Republic to determine content of plant available S. Using this method, it was found that the content of S extracted by Mehlich 3 (SM3) closely correlates to Sav in both topsoil and subsoil (r = 0.958 in 1997 and 0.990 in 2019, both at p < 0.001). We also found that, on average, during the entire experiment, all treatments had increased yields over Cont (135–147%) and increased S uptake (291, 192, 180, and 246% of Cont for AS, UAN, UAN + PK, and UAN + PMgS, respectively). Examining the changes from 1997 to 2019 in topsoil (0–30 cm depth), we discovered a decrease of S content in Sw, Sads, Sav, and St fractions on all treatments to an average of 34.6%, 65.8%, 42.2%, and 78.6% of their initial values. The exception was AS treatment, which doubled its initial content in mineral fractions and maintained the same levels of St, and which we attribute to the very high dose of S on this treatment (142 kg ha−1 year−1). Using the simple balance method, AS and UAN + PMgS treatments lost 142.2 and 95.3 kg S ha−1 year−1 to other sinks, except plant uptake, from the entire soil profile (0–60 cm) during 23 years of experiment. Other treatments also show significant losses with the exception of Fallow. Given these results, it is clear that content of sulfur in soil is generally decreasing and attention should be paid mainly towards minimizing of its losses.

In the Model Cell Lines of Moderately and Poorly Differentiated Endometrial Carcinoma, Estrogens Can Be Formed via the Sulfatase Pathway

Endometrial cancer (EC) is the most common gynecological malignancy in resource-abundant countries. The majority of EC cases are estrogen dependent but the mechanisms of estrogen biosynthesis and oxidative metabolism and estrogen action are not completely understood. Here, we evaluated formation of estrogens in models of moderately and poorly differentiated EC: RL95-2 and KLE cells, respectively. Results revealed high expression of estrone-sulfate (E1-S) transporters (SLCO1A2, SLCO1B3, SLCO1C1, SLCO3A1, SLC10A6, SLC22A9), and increased E1-S uptake in KLE vs RL95-2 cells. In RL95-2 cells, higher levels of sulfatase and better metabolism of E1-S to E1 were confirmed compared to KLE cells. In KLE cells, disturbed balance in expression of HSD17B genes led to enhanced activation of E1 to E2, compared to RL95-2 cells. Additionally, increased CYP1B1 expression and down-regulation of genes encoding phase II metabolic enzymes: COMT, NQO1, NQO2, and GSTP1 suggested decreased detoxification of carcinogenic metabolites in KLE cells. Results indicate that in model cell lines of moderately and poorly differentiated EC, estrogens can be formed via the sulfatase pathway.

Interaction Between Sulfur and Iron in Plants

It is well known that S interacts with some macronutrients, such as N, P, and K, as well as with some micronutrients, such as Fe, Mo, Cu, Zn, and B. From our current understanding, such interactions could be related to the fact that: (i) S shares similar chemical properties with other elements (e.g., Mo and Se) determining competition for the acquisition/transport process (SULTR transporter family proteins); (ii) S-requiring metabolic processes need the presence of other nutrients or regulate plant responses to other nutritional deficiencies (S-containing metabolites are the precursor for the synthesis of ethylene and phytosiderophores); (iii) S directly interacts with other elements (e.g., Fe) by forming complexes and chemical bonds, such as Fe-S clusters; and (iv) S is a constituent of organic molecules, which play crucial roles in plants (glutathione, transporters, etc.). This review summarizes the current state of knowledge of the interplay between Fe and S in plants. It has been demonstrated that plant capability to take up and accumulate Fe strongly depends on S availability in the growth medium in both monocots and dicot plants. Moreover, providing S above the average nutritional need enhances the Fe content in wheat grains, this beneficial effect being particularly pronounced under severe Fe limitation. On the other hand, Fe shortage induces a significant increase in the demand for S, resulting in enhanced S uptake and assimilation rate, similar to what happens under S deficiency. The critical evaluation of the recent studies on the modulation of Fe/S interaction by integrating old and new insights gained on this topic will help to identify the main knowledge gaps. Indeed, it remains a challenge to determine how the interplay between S and Fe is regulated and how plants are able to sense environmental nutrient fluctuations and then to adapt their uptake, translocation, assimilation, and signaling. A better knowledge of the mechanisms of Fe/S interaction might considerably help in improving crop performance within a context of limited nutrient resources and a more sustainable agriculture.

Evaluation of the Sulphur-Supplying Ability of Soils to Support Plant Growth and Assessment of Relative Crop Response to Sulphur Application through Neubauer Technique

Sulphur plays a vital role in the nutrition of oilseeds and pulses. Along with nitrogen and phosphorus, it plays an important role in the formation of proteins and is involved in the metabolic and enzymatic processes of all living cells. Several biological techniques have been studied in order to assess sulphur deficiency or sufficiency in different groups of sulphur fertilizer for achieving the optimum yield of crops of which Neubauer technique is generally considered as one such tool that can be used for piloting the sulphur supplying capacity of the soils to supplement its requirement for the establishment of the plant. Surface (0-15 cm) soil samples from typical rice and pulse growing fields spread over the dominant soil groups of West Bengal which belong under 16 identified soil series were collected for this study. In order to assess sulphur availability in soils Neubauer technique was employed. Under sulphur treatment, the lowest dry matter yield and uptake by shoot was recorded in Bankul soil. Among the soils, the lowest root dry matter yield at control treatment was recorded in patapahari soil and the highest was in Hijalgara soil. A similar trend was also observed in case of S uptake by the shoot. While highest dry matter yield and maximum sulphur uptake by shoot was registered in Sukhnibasa and kusmi soil respectively. Likewise for N, P and K elements, the Neubauer technique may be used as one of the biological techniques for evaluating S response to crops as well as S supplying capacity of the soil to support plant growth.

Competition for S-containing amino acids between rhizosphere microorganisms and plant roots: the role of cysteine in plant S acquisition

Plant S deficiency is common, but the role of S-containing amino acids such as cysteine in plant S uptake is unknown. We applied 14C-, 35S-, 13C-, and 15N-labelled cysteine to wheat and oilseed rape rhizospheres and traced the plants’ elemental uptake. Both plants absorbed 0.37–0.81% of intact cysteine after 6 h with no further increase after 24 h. They absorbed 1.6–11.5% 35S and 12.3–7.6% 15N from cysteine after 24 h and utilised SO42− as their main S source (75.5–86.4%). Added and naturally occurring cysteine-S contributed 5.6 and 1.1% of total S uptake by wheat and oilseed rape, respectively. Cysteine and inorganic S derived from cysteine contributed 24.5 and 13.6% of uptake for wheat and oilseed rape, respectively, after 24 h. Oilseed rape absorbed ~10-fold more S from cysteine and SO42− than did wheat. The highest absorption of free cysteine should be in the organic-rich soil patches. Soil microorganisms rapidly decomposed cysteine (t1/2 = 1.37 h), and roots absorbed mineralised inorganic N and S. After 15 min, 11.7–14.3% of the 35S-cysteine was retained in the microbial biomass, while 30.2–36.7% of the SO42− was released, suggesting that rapid microbial S immobilisation occurs after cysteine addition. Plants acquire N and S from cysteine via unidirectional soil-to-root nutrient flow, and cysteine is an important S source for plants.

Nutrient Uptake Studies under Varying Drip Irrigation Regimes and Fertigation Levels in Rabi Cauliflower in Telangana State

A field study was conducted with different drip irrigation regimes and NK fertigation levels on cauliflower at Hyderabad, Telangana during rabi 2019-2020. The experiment was laid out in a split plot design with three drip irrigation regimes viz., 0.6, 0.8 and 1.0 Epan as main plots and three drip NK fertigation levels of control (N0K0), 50 % recommended dose of NK (N40 K50) and 100 % recommended dose of NK (N80 K100) as sub plots altogether nine treatments and replicated thrice. Drip irrigation scheduled at 1.0 Epan recorded significantly higher curd yield (18.7 t ha-1) than 0.8 Epan (17.1 t ha-1) and 0.6 Epan (15.0 t ha-1). NPK and S uptake were significantly higher in irrigation scheduled at 1.0 Epan than 0.8 and 0.6 Epan during all stages except at 30 DAT and harvest where S uptake was found to be non significant among different irrigation levels. Drip fertigation at 100 % recommended dose of NK recorded significantly higher curd yield (23.8 t ha-1) than 50 % recommended dose of NK (19.7 t ha-1) and N0K0 (7.2 t ha-1). Drip NK fertigation levels significantly increased the NPK and S uptake with each increment in NK fertigation level from N0K0 to 100 % recommended dose of NK at all stages.

Long-term fate of fertilizer sulfate- and elemental S in co-granulated fertilizers

In previous studies, we assessed sulfur (S) uptake by crops from elemental S (ES) and sulfate-S (SO4-S) in S-fortified monoammonium phosphate fertilizers over two years. The recovery by the crop ranged from 16 to 28% for ES and from 9 to 86% for SO4-S. Here, we used a model which takes into account organic S cycling, SO4-S leaching and ES oxidation to explain the observed recoveries. Higher recoveries of ES than SO4-S in two of the four sites could be explained by partial leaching of SO4-S and relatively fast oxidation of ES, due to a warm climate and high S-oxidizing soils. The same model was used for longer-term (5-year) predictions, and a sensitivity analysis was carried out. The size of the labile soil S pool and total S uptake strongly affected the recovery of both SO4-S and ES. Predicted recoveries after 5 years were over threefold higher for a small than for a large labile organic S pool and for a high-uptake than for a low-uptake scenario. Leaching mainly affected SO4-S, with predicted recoveries halved under a high-leaching scenario. Slow oxidation resulted in recoveries in the first year being fourfold lower for ES than for SO4-S or even lower in case of a long lag-time. However, it is predicted that total recoveries of ES will eventually reach those of SO4-S or exceed them if there is SO4-S leaching. Our model demonstrates that long-term trials are needed to evaluate the true effectiveness of a slow-release fertilizer source such as ES.

Altered Profile of E1-S Transporters in Endometrial Cancer: Lower Protein Levels of ABCG2 and OSTβ and Up-Regulation of SLCO1B3 Expression

Endometrial cancer (EC) is associated with increased estrogen actions. Locally, estrogens can be formed from estrone-sulphate (E1-S) after cellular uptake by organic anion-transporting polypeptides (OATP) or organic anion transporters (OAT). Efflux of E1-S is enabled by ATP Binding Cassette transporters (ABC) and organic solute transporter (OST)αβ. Currently, 19 E1-S transporters are known but their roles in EC are not yet understood. Here, we analysed levels of E1-S transporters in Ishikawa (premenopausal EC), HEC-1-A (postmenopausal EC), HIEEC (control) cell lines, in EC tissue, examined metabolism of steroid precursor E1-S, studied effects of OATPs’ inhibition and gene-silencing on E1-S uptake, and assessed associations between transporters and histopathological data. Results revealed enhanced E1-S metabolism in HEC-1-A versus Ishikawa which could be explained by higher levels of OATPs in HEC-1-A versus Ishikawa, especially 6.3-fold up-regulation of OATP1B3 (SLCO1B3), as also confirmed by immunocytochemical staining and gene silencing studies, lower ABCG2 expression and higher levels of sulfatase (STS). In EC versus adjacent control tissue the highest differences were seen for ABCG2 and SLC51B (OSTβ) which were 3.0-fold and 2.1-fold down-regulated, respectively. Immunohistochemistry confirmed lower levels of these two transporters in EC versus adjacent control tissue. Further analysis of histopathological data indicated that SLCO1B3 might be important for uptake of E1-S in tumours without lymphovascular invasion where it was 15.6-fold up-regulated as compared to adjacent control tissue. Our results clearly indicate the importance of E1-S transporters in EC pathophysiology and provide a base for further studies towards development of targeted treatment.

99mTc-labelled PSMA ligand for radio-guided surgery in nodal metastatic prostate cancer: proof of principle

Purpose Intraoperative identification of prostate cancer (PCa) lymph node (LN) metastases (LNM) detected by preoperative PSMA PET/CT may be facilitated by PSMA radio-guided surgery (RGS) with use of a γ-probe. Earlier we demonstrated excellent performance of the 111In-labelled PSMA ligand DKFZ-617 ([111In]In-PSMA-617) in RGS for ex situ distinction of LN vs LNM at lymphadenectomy (LA) at a single LN level. In comparison with indium-111, technetium-99m has better physical properties for γ-probe measurements, better availability and lower radiation exposure for patients and medical personnel. Against this background, we evaluated the uptake of 99mTc-PSMA-I&S ligand at the level of single LN and its power to discriminate between unaffected LN and LNM. Methods Six patients with PCa with the suspicion of LNM on preoperative PSMA-PET/CT underwent [99mTc]Tc-PSMA-I&S RGS (4 salvage LA, 2 primary LA) with intravenous injection of [99mTc]Tc-PSMA-I&S 24 h prior to surgery. Resected samples were isolated manually aiming at the level of single LN. Uptake measurements were done ex situ with a high-purity germanium detector. Receiver operating characteristic (ROC) analysis was performed based on [99mTc]Tc-PSMA-I&S uptake expressed as lean body mass standard uptake value (SUL). Results Separation of the tissue samples from 73 subregions resulted in 498 single samples. After final histopathology 356 LN, 160 LNM und 11 non-nodal PCa samples were identified. Median SUL of tumor-free samples (0.26) and samples with cancer (3.5) was significantly different (p < 0.0001). ROC analysis revealed an area under the curve (AUC) of 0.917 (95% CI 0.89–0.95). Using a SUL cutoff of 1.1, sensitivity, specificity, positive predictive value, and negative predictive values were 76.6%, 94.4%, 89.4% and 86.9%. Conclusion Ex situ analysis of [99mTc]Tc-PSMA-I&S uptake at single LN level showed good diagnostic performance for the ex situ distinction of tumor-bearing vs tumor-free LN during RGS.

The role of arbuscular mycorrhiza and organosulfur mobilizing bacteria in plant sulphur supply

AM fungi are enhancing growth and health of many land plants but only some of these beneficial mechanisms are well understood. This study aimed to uncover the role of bacteria colonising AM fungi in organically-bound sulfur (S) mobilisation, the dominant S pools in soil that are not directly available to plants. The effect of an intact AM symbiosis with access to stable isotope organo-34S enriched soils encased in 35 µm mesh cores was tested in microcosms with Agrostis stolonifera and Plantago lanceolata. At 3 month intervals, the plant shoots were analysed for 34S uptake. After 9 months, hyphae and associated soil was picked from static (mycorrhizal) and rotating (severed hyphae) mesh cores and corresponding rhizosphere soil was sampled for bacterial analysis. AM symbiosis increased uptake of 34S from organo-34S enriched soil at early stages of plant growth when S demand appeared to be high. The static (mycorrhizal) treatments were shown to harbour larger populations of cultivable heterotrophs and sulfonate mobilising bacteria. Microbial communities were significantly different in the hyphosphere of mycorrhizal hyphae and hyphae not associated to plant hosts. Sulfate ester (arylsulfatase enzyme assay, atsA gene) and sulfonate mobilising activity (asfA gene) was altered by an intact AM symbiotic partnership which stimulated the genera Azospirillum, Burkholderia and Polaromonas. Illumina sequencing revealed that AM symbiosis led to community shifts, reduced diversity and dominance of the Planctomycetes and Proteobacteria. This study demonstrated that AM symbioses can promote organo-S mobilization and plant uptake through interaction with hyphospheric bacteria.Research highlightsAM hyphae enhanced uptake of organically bound 34S at early stages of growth.AM hyphosphere harboured a large population of organo-S desulfurizing bacteria.Microbial communities significantly differed in rotating and static mesh cores.AM hyphae influenced bacterial sulfate ester and sulfonate mobilising activity.AM hyphae reduced bacterial diversity, increased Planctomycetes and Proteobacteria abundance.