Sex-Dependent Variation of Pumpkin (Cucurbita maxima cv. Big Max) Nectar and Nectaries as Determined by Proteomics and Metabolomics.

{"sci_version": "1.2", "schema": "https://corpus.bntrg.co.uk/sci/1.0/sci.schema.json", "id": "pmid:30008725", "kind": "science-record", "revision": 7, "content_hash": "sha256:ee42ca1bdc8a782ab7b144b3dd9180da8151309626684f924e924c87d77cde9f", "created_at": "2026-11-01T15:40:35Z", "updated_at": "2026-11-01T21:59:56Z", "generator": {"name": "corpus-assay-engine", "run_id": "reading-sci-2026-11-01"}, "paper": {"state": "complete", "title": "Sex-Dependent Variation of Pumpkin (Cucurbita maxima cv. Big Max) Nectar and Nectaries as Determined by Proteomics and Metabolomics.", "doi": "10.3389/fpls.2018.00860", "pmid": "30008725", "authors": ["Elizabeth C Chatt", "Patrick von Aderkas", "Clay J Carter", "Derek Smith", "Monica Elliott", "Basil J Nikolau"], "journal": "Frontiers in plant science", "year": 2018, "abstract": "Nectar is a floral reward that sustains mutualisms with pollinators, which in turn, improves fruit set. While it is known that nectar is a chemically complex solution, extensive identification and quantification of this complexity has been lacking. Cucurbita maxima cv. Big Max, like many cucurbits, is monoecious with separate male and female flowers. Attraction of bees to the flowers through the reward of nectar is essential for reproductive success in this economically valuable crop. In this study, the sex-dependent variation in composition of male and female nectar and the nectaries were defined using a combination of GC-MS based metabolomics and LC-MS/MS based proteomics. Metabolomics analysis of nectar detected 88 metabolites, of which 40 were positively identified, and includes sugars, sugar alcohols, aromatics, diols, organic acids, and amino acids. There are differences in 29 metabolites between male and female nectar. The nectar proteome consists of 45 proteins, of which 70% overlap between nectar types. Only two proteins are unique to female nectar, and 10 are specific to male nectar. The nectary proteome data, accessible at ProteomeXchange with identifier PXD009810, contained 339 identifiable proteins, 71% of which were descriptively annotatable by homology to Plantae. The abundance of 45 proteins differs significantly between male and female nectaries, as determined by iTRAQ labeling. This rich dataset significantly expands the known complexity of nectar composition, supports the hypothesis of H+-driven nectar solute export, and provides genetic and chemical targets to understand plant-pollinator interactions.", "claims": [{"id": "claim-method", "statement": "Relative metabolite concentrations between male and female nectars were compared using a two-tailed independent samples t-test with resulting p-values corrected for multiple testing using the Benjamini and Hochberg’s method. A Mann Whitney test with Benjamini and Hochberg method for multiple testing correction was used to calculate p-values based on the log fold change of protein abundance between male and female nectaries.", "kind": "methodological", "target": null, "evidence": [{"asset": "source:pmid:30008725", "locator": "sections[12] \"Statistical Analyses\" paragraph 2", "quote": "Relative metabolite concentrations between male and female nectars were compared using a two-tailed independent samples t-test with resulting p-values corrected for multiple testing using the Benjamini and Hochberg’s method. A Mann Whitney test with Benjamini and Hochberg method for multiple testing correction was used to calculate p-values based on the log fold change of protein abundance between male and female nectaries."}], "state": "complete"}, {"id": "claim-data-access", "statement": "The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium1 via PRIDE (Vizcaíno et al., 2016) partner repository, with the dataset identifier PXD009810 and 10.6019/PXD009810.", "kind": "methodological", "target": null, "evidence": [{"asset": "source:pmid:30008725", "locator": "sections[11] \"Proteomics Data Processing\" paragraph 2", "quote": "The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium1 via PRIDE (Vizcaíno et al., 2016) partner repository, with the dataset identifier PXD009810 and 10.6019/PXD009810."}], "state": "complete"}, {"id": "claim-target-result", "statement": "Male and female nectar differed significantly in 29 metabolites, with metabolite comparisons using two-tailed independent-samples t-tests followed by Benjamini–Hochberg multiple-testing correction; the proteomics source data are accessible through ProteomeXchange via PRIDE under PXD009810.", "kind": "quantitative", "target": {"value": 71.0, "unit": "per cent", "tolerance": null, "source": "The nectary proteome data, accessible at ProteomeXchange with identifier PXD009810, contained 339 identifiable proteins, 71% of which were descriptively annotatable by homology to Plantae."}, "evidence": [{"asset": "source:pmid:30008725", "locator": "sections[15] \"GC-MS Identification of Nectar Metabolites\" paragraph 2", "quote": "A total of 29 analytes were found to differ significantly in abundance between male and female nectar (Figure 3)."}, {"asset": "source:pmid:30008725", "locator": "sections[0] \"Abstract\" paragraph 1", "quote": "The nectary proteome data, accessible at ProteomeXchange with identifier PXD009810, contained 339 identifiable proteins, 71% of which were descriptively annotatable by homology to Plantae."}], "state": "complete"}], "gaps": []}, "experiment": {"state": "partial", "objective": "Male and female nectar differed significantly in 29 metabolites, with metabolite comparisons using two-tailed independent-samples t-tests followed by Benjamini–Hochberg multiple-testing correction; the proteomics source data are accessible through ProteomeXchange via PRIDE under PXD009810.", "steps": [{"id": "read_published_estimate", "order": 1, "name": "Read the published estimate from the source", "kind": "other", "state": "complete", "blocked_on": null, "description": "The claim, method and evidence span published with the source article.", "duration_hours": null, "parameters": {}, "inputs": ["source:pmid:30008725"], "outputs": ["the published estimate and its evidence"], "instruments": [], "reagents": []}, {"id": "obtain_source_data", "order": 2, "name": "Obtain the source data from the named repository", "kind": "data-preparation", "state": "blocked", "blocked_on": "data:accession_absent", "description": "The GEO series accession resolves and its sample accessions are listed. This lane did not download the dataset or read its licence.", "duration_hours": null, "parameters": {}, "inputs": [], "outputs": ["the source data with its repository provenance"], "instruments": [], "reagents": []}, {"id": "run_analysis", "order": 3, "name": "Run the published analysis", "kind": "analysis", "state": "blocked", "blocked_on": "method:group_comparison_mann_whitney", "description": "Apply the paper's statistical method to the resolved series and compare the result with the published target.", "duration_hours": null, "parameters": {}, "inputs": [], "outputs": ["the replicated result and its comparison"], "instruments": [], "reagents": []}], "materials": [], "instruments": [], "reagents": [], "conditions": {}, "gaps": ["step:run_analysis blocked on method:group_comparison_mann_whitney", "step:obtain_source_data blocked on data:accession_absent"]}, "data": {"state": "partial", "assets": [{"id": "source:pmid:30008725", "role": "manuscript", "format": "xml", "media_type": "application/xml", "uri": "https://doi.org/10.3389/fpls.2018.00860", "sha256": "sha256:41e36e916f11664cc84d615d73dc133a16f0bf3354cfa2da6f04d27c1de761e3", "bytes": 55416, "access": "open", "state": "resolved", "reader": null, "reader_status": "reader_required", "identifier": "10.3389/fpls.2018.00860", "version": null, "note": "Full article fetched from PMC; the checksum covers the rendered section body, not the original XML bytes.", "structure": {"pmcid": "PMC6034135", "source": "europe_pmc_fulltext", "coverage": "whole_body", "text_hash_scope": "rendered_section_body"}}, {"id": "asset:table:pmid:30008725:1", "role": "table", "format": "jats-table", "media_type": "application/vnd.jats.table+json", "uri": null, "sha256": "sha256:f8f827eab16f3df1e90bbe1aa18eda4e688a3781eb7bc434c3d77fedd7d8060d", "bytes": 1649, "access": "open", "state": "verified", "reader": "read_table", "reader_status": "available", "identifier": "section[15]/table-wrap[1]#T1", "version": null, "note": "Amino acids identified in Cucurbita maxima nectar reported as mean ± SE (n = 6).", "structure": {"pmcid": "PMC6034135", "section_index": 15, "section_title": "GC-MS Identification of Nectar Metabolites", "row_count": 21, "column_count": 5}, "table": {"label": "Table 1", "caption": "Amino acids identified in Cucurbita maxima nectar reported as mean ± SE (n = 6).", "rows": [["Amino Acid", "Concentration (μM)", "% of total amino acid"], ["", "Female", "Male", "Female", "Male"], ["∗Alanine", "117 ± 14", "212 ± 40", "42.8 ± 3.4", "52.9 ± 3.4"], ["∗Glycine", "3.6 ± 0.7", "7.6 ± 1.3", "1.3 ± 0.2", "1.9 ± 0.2"], ["Serine", "5.7 ± 1.4", "9.5 ± 2.2", "1.9 ± 0.4", "2.4 ± 0.5"], ["Proline", "30.5 ± 4.6", "45.2 ± 9.2", "11.3 ± 1.6", "12.6 ± 3.2"], ["Asparagine", "10.2 ± 1.8", "7.7 ± 1.6", "3.6 ± 0.4", "2.1 ± 0.6"], ["Aspartic acid", "6.9 ± 2.8", "5.2 ± 0.7", "2.4 ± 0.8", "1.4 ± 0.2"], ["Glutamic acid", "11.9 ± 2.4", "12.5 ± 1.6", "4.4 ± 0.9", "3.3 ± 0.5"], ["Tyrosine", "0.52 ± 0.15", "0.75 ± 0.17", "0.17 ± 0.04", "0.19 ± 0.04"], ["∗Tryptophan", "0.23 ± 0.07", "0.57 ± 0.11", "0.08 ± 0.02", "0.16 ± 0.03"], ["Valine", "11.9 ± 1.7", "14.4 ± 2.5", "4.3 ± 0.4", "3.6 ± 03"], ["Leucine", "3.4 ± 0.4", "4.8 ± 1.4", "1.2 ± 0.1", "1.1 ± 0.2"], ["Isoleucine", "11.9 ± 2.0", "11.8 ± 2.8", "4.4 ± 0.7", "2.9 ± 0.6"], ["Threonine", "1.3 ± 0.4", "2.2 ± 0.3", "0.48 ± 0.11", "0.59 ± 0.09"], ["Methionine", "1.4 ± 0.3", "1.9 ± 0.6", "0.51 ± 0.10", "0.45 ± 0.09"], ["Phenylalanine", "11.5 ± 1.8", "14.0 ± 1.7", "4.2 ± 0.6", "3.6 ± 0.3"], ["Lysine", "0.24 ± 0.09", "0.72 ± 0.31", "0.09 ± 0.03", "0.19 ± 0.08"], ["β-Alanine", "13.1 ± 2.7", "15.5 ± 3.1", "4.6 ± 0.7", "4.4 ± 1.1"], ["GABA", "32.9 ± 4.3", "21.8 ± 4.4", "12.1 ± 1.3", "5.9 ± 1.4"], ["4-Hydroxyproline", "0.87 ± 0.66", "0.54 ± 0.12", "0.33 ± 0.24", "0.14 ± 0.03"]], "row_count": 21, "column_count": 5, "numeric_cells": 77, "header_rows": 2, "locator": "section[15]/table-wrap[1]#T1"}}], "gaps": []}, "analysis": {"state": "partial", "methods": [{"id": "method-1", "family": "group_comparison", "specific": "mann_whitney", "label": "Group comparison", "dsl_operations": [], "missing_operations": ["group_comparison_mann_whitney"], "expressible": false, "parameters": {}, "data_shapes": ["two_or_more_groups_continuous"], "evidence": {"score": 0.8, "band": "high", "quote": "Mann Whitney"}}, {"id": "method-2", "family": null, "specific": null, "label": "Two-tailed independent samples t-test for relative metabolite concentrations; Mann–Whitney test for relative protein abundance.", "dsl_operations": [], "missing_operations": [], "expressible": null, "parameters": {}, "data_shapes": [], "evidence": {"score": 1.0, "band": "verbatim", "quote": "Relative metabolite concentrations between male and female nectars were compared using a two-tailed independent samples t-test with resulting p-values corrected for multiple testing using the Benjamini and Hochberg’s method. 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