Short-term proteomic dynamics reveal metabolic factory for active extrafloral nectar secretion by Acacia cornigera ant-plants

Authors

  • Domancar Orona-Tamayo,

    1. Departamento de Ingeniería Genética, Centro de Investigación y de Estudios Avanzados-Irapuato (CINVESTAV), Guanajuato, Mexico
    2. Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria (UMICH), Morelia, Michoacan, Mexico
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    • These authors have contributed equally to this paper.
  • Natalie Wielsch,

    1. Mass Spectrometry Group, Max Planck Institute for Chemical Ecology, Jena, Germany
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    • These authors have contributed equally to this paper.
  • María Escalante-Pérez,

    1. Departamento de Ingeniería Genética, Centro de Investigación y de Estudios Avanzados-Irapuato (CINVESTAV), Guanajuato, Mexico
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  • Ales Svatos,

    1. Mass Spectrometry Group, Max Planck Institute for Chemical Ecology, Jena, Germany
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  • Jorge Molina-Torres,

    1. Departamento de Biotecnología y Bioquímica, CINVESTAV, Irapuato, Guanajuato, Mexico
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  • Alexander Muck,

    1. Mass Spectrometry Group, Max Planck Institute for Chemical Ecology, Jena, Germany
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  • Enrique Ramirez-Chávez,

    1. Departamento de Biotecnología y Bioquímica, CINVESTAV, Irapuato, Guanajuato, Mexico
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  • Rosa-María Ádame-Alvarez,

    1. Departamento de Ingeniería Genética, Centro de Investigación y de Estudios Avanzados-Irapuato (CINVESTAV), Guanajuato, Mexico
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  • Martin Heil

    Corresponding author
    • Departamento de Ingeniería Genética, Centro de Investigación y de Estudios Avanzados-Irapuato (CINVESTAV), Guanajuato, Mexico
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For correspondence (e-mail mheil@ira.cinvestav.mx).

Summary

Despite the ecological and evolutionary importance of nectar, mechanisms controlling its synthesis and secretion remain largely unknown. It is widely believed that nectar is ‘secreted phloem sap’, but current research reveals a biochemical complexity that is unlikely to stem directly from the phloem. We used the short daily peak in production of extrafloral nectar by Acacia cornigera to investigate metabolic and proteomic dynamics before, during and after 2 h of diurnal secretion. Neither hexoses nor dominating nectar proteins (nectarins) were detected in the phloem before or during nectar secretion, excluding the phloem as the direct source of major nectar components. Enzymes involved in the anabolism of sugars, amino acids, proteins, and nectarins, such as invertase, β–1,3–glucanase and thaumatin-like protein, accumulated in the nectary directly before secretion and diminished quantitatively after the daily secretion process. The corresponding genes were expressed almost exclusively in nectaries. By contrast, protein catabolic enzymes were mainly present and active after the secretion peak, and may function in termination of the secretion process. Thus the metabolic machinery for extrafloral nectar production is synthesized and active during secretion and degraded thereafter. Knowing the key enzymes involved and the spatio-temporal patterns in their expression will allow elucidation of mechanisms by which plants control nectar quality and quantity.

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