Fig. 1

Label-free, high-throughput LC-MS/MS quantification of the SIV pollen tube secretome. a Numbers of peptides identified by LC-MS/MS. Box plots summarize peptide number distribution per protein accession within a single sample replicate with the median value designated by the solid red line. Appended pie charts show the distribution of peptide counts in arbitrary bins. b SIV-PS samples showing the reproducibility and dynamics of the secreted protein groups (threefold or more abundant in at least two SIV-PS samples relative to unpollinated controls and identified by at least three or more peptides). c Size distribution of pollen tube-secreted proteins, showing predominant bias towards small secreted proteins. SIV-PS1–2 are used as representatives of all four replicates. d In silico analysis of pollen tube-secreted proteins using SMART and Pfam databases of overrepresented protein families and domains. The vertical white line indicates significance cutoff (p < 0.05). e Classified pollen tube-secreted proteins based on the Top3 algorithm showing the dominant presence of unconventionally secreted proteins, although these have comparable protein abundance to conventionally secreted proteins. f Heatmap derived from the Agilent tobacco microarray [19, 20] of transcripts encoding identified pollen tube-secreted proteins showing predominantly gametophytic enrichment. g Validated expression profile by semi-quantitative RT-PCR of selected pollen tube-secreted proteins assessed in this study. All samples analyzed were from N. tabacum. NtPsCRP1/2 Nicotiana tabacum cysteine-rich polypeptide protein 1 and 2, EIG-E80 elicitor inducible gene subE80, LLG3 Lorelei-like GPI-anchored protein 3, PT semi in vivo pollen tubes, Ov unfertilized ovules, Inf inflorescence