pp 1–13 | Cite as

Proteomics and post-secretory content adjustment of Nicotiana tabacum nectar

  • Xue-Long Ma
  • Richard I. Milne
  • Hong-Xia Zhou
  • Yue-Qin Song
  • Jiang-Yu Fang
  • Hong-Guang ZhaEmail author
Original Article


Main conclusion

The tobacco nectar proteome mainly consists of pathogenesis-related proteins with two glycoproteins. Expression of nectarins was non-synchronous, and not nectary specific. After secretion, tobacco nectar changed from sucrose rich to hexose rich.


Floral nectar proteins (nectarins) play important roles in inhibiting microbial growth in nectar, and probably also tailoring nectar chemistry before or after secretion; however, very few plant species have had their nectar proteomes thoroughly investigated. Nectarins from Nicotiana tabacum (NT) were separated using two-dimensional gel electrophoresis and then analysed using mass spectrometry. Seven nectarins were identified: acidic endochitinase, β-xylosidase, α-galactosidase, α-amylase, G-type lectin S-receptor-like serine/threonine-protein kinase, pathogenesis-related protein 5, and early nodulin-like protein 2. An eighth nectarin, a glycoprotein with unknown function, was identified following isolation from NT nectar using a Qproteome total glycoprotein kit, separation by SDS-PAGE, and identification by mass spectrometry. Expression of all identified nectarins, plus four invertase genes, was analysed by qRT PCR; none of these genes had nectary-specific expression, and none had synchronous expression. The total content of sucrose, hexoses, proteins, phenolics, and hydrogen peroxide were determined at different time intervals in secreted nectar, both within the nectar tube (in vivo) and following extraction from it during incubation at 30 °C for up to 40 h in plastic tubes (in vitro). After secretion, the ratio of hexose to sucrose substantially increased for in vivo nectar, but no sugar composition changes were detected in vitro. This implies that sucrose hydrolysis in vivo might be done by fixed apoplastic invertase. Both protein and hydrogen peroxide levels declined in vitro but not in vivo, implying that some factors other than nectarins act to maintain their levels in the flower, after secretion.


Floral nectar Gene expression pattern Glycoprotein Invertase Nectarin Post-secretory adjustment Tobacco 



Two-dimensional gel electrophoresis


Early nodulin-like protein 2


Nicotiana tabacum


Pathogenesis related



This work was supported by the Natural Science Foundation of Anhui Province (1608085MC65 to HG Zha) and Science Foundation of Huangshan University (2014XKJQ004 to HG Zha, and 2015 XKJQ 005 to HX Zhou).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Supplementary material

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Supplementary material 2 (DOCX 25 kb)
425_2019_3258_MOESM3_ESM.xlsx (11 kb)
Supplementary material 3 (XLSX 11 kb)


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.College of Life and Environment SciencesHuangshan UniversityHuangshanChina
  2. 2.Institute of Molecular Plant SciencesUniversity of EdinburghEdinburghUK

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