Abstract
The pollination droplet is a highly conservative pollination mechanism that is observed in all major gymnosperm taxa. Proteomics analysis of the pollination drops was carried out on four gymnosperm species: Juniperus communis (common juniper), Juniperus oxycedrus (prickly juniper), Chamaecyparis lawsoniana (Port Orford cedar), and Welwitschia mirabilis. Pollination drop proteins were purified by SDS-PAGE, and the most abundant proteins were analyzed by mass spectrometry and sequenced. Based on BLAST searching of combined amino acid sequences, the following proteins were identified in the following species: an 83-kDa subtilisin-like proteinase, a 62-kDa glycosyl hydrolase, a 47.5-kDa glucan 1,3-β-glucosidase precursor, a 30-kDa chitinase, and a 25-kDa thaumatin-like protein were identified in J. communis; a 30-kDa chitinase, a 25-kDa thaumatin-like protein, and a 32.5-kDa glucanase-like protein were identified in J. oxycedrus; an 83-kDa subtilisin-like proteinase, a 62-kDa β-d-glucan exohydrolase, a 47.5-kDa glucan 1,3-β-glucosidase, and two 25-kDa thaumatin-like proteins were identified in C. lawsoniana, and a 25-kDa chitinase was identified in W. mirabilis. Based on protein identifications, there is strong evidence that the pollination drop functions in both pathogen defense and pollen development. The discovery of similarities in terms of peptide sequence and protein identifications indicates that ovular secretions are functionally conservative, and that they are essential to reproductive success.
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Acknowledgments
We are grateful to Leslie Elliott, Jerry Hill, Scott Kolpak, Angelia Kegley, and Jerry Berdeen at the Dorena Lake GRC for allowing us to sample from C. lawsoniana, and to Doug Ewing at the University of Washington greenhouse for allowing us to sample from W. mirabilis. We would also like to thank Derek Smith, Leanne Ohlund, and Phil Jakubowski at the University of Victoria Genome BC Proteomics Centre for analytical support. Special thanks to Andrea Coulter, Adrienne Robb for many hours of sample collection from C. lawsoniana and W. mirabilis. This work was sponsored by the Natural Sciences and Engineering Research Council of Canada (NSERC).
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Communicated by Yongbiao Xue.
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Wagner, R.E., Mugnaini, S., Sniezko, R. et al. Proteomic evaluation of gymnosperm pollination drop proteins indicates highly conserved and complex biological functions. Sex Plant Reprod 20, 181–189 (2007). https://doi.org/10.1007/s00497-007-0054-8
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DOI: https://doi.org/10.1007/s00497-007-0054-8