Antisense phenotypes reveal a role for SHY, a pollen-specific leucine-rich repeat protein, in pollen tube growth

Authors

  • Virginie Guyon,

    1. School of Molecular Biosciences, Washington State University, Pullman, WA 99163-4234, USA
    Search for more papers by this author
    • Present address: Biogemma, 24, Avenue des Landais, 63170 Aubière, France.

  • Wei-hua Tang,

    1. Plant Gene Expression Center, USDA/ARS and Department of Plant and Microbial Biology, University of California, Berkeley, CA 94710, USA
    Search for more papers by this author
  • Maurilia M. Monti,

    1. School of Molecular Biosciences, Washington State University, Pullman, WA 99163-4234, USA
    Search for more papers by this author
    • Present address: Istituto per la Protezione delle Piante (IPP), CNR, Sezione di Portici, Via Università 133, 80055, Portici, Napoli, Italy.

  • Alessandro Raiola,

    1. Department of Plant Biology, University La Sapienza, 00185 Rome, Italy
    Search for more papers by this author
    • §

      Present address: Dipartimento Territorio e Sistemi Agro-Forestali, Università degli Studi di Padova, 35020 Legnaro, Padova, Italy.

  • Giulia De Lorenzo,

    1. Department of Plant Biology, University La Sapienza, 00185 Rome, Italy
    Search for more papers by this author
  • Sheila McCormick,

    1. Plant Gene Expression Center, USDA/ARS and Department of Plant and Microbial Biology, University of California, Berkeley, CA 94710, USA
    Search for more papers by this author
  • Loverine P. Taylor

    Corresponding author
    1. School of Molecular Biosciences, Washington State University, Pullman, WA 99163-4234, USA
    Search for more papers by this author

(fax 509-335-1907; e-mail ltaylor@wsu.edu).

Summary

SHY, a pollen-specific gene identified in a screen for genes upregulated at pollen germination (Guyon et al., 2000), encodes a leucine-rich repeat (LRR) protein that is predicted to be secreted. To test if SHY plays an important role during pollen germination, we generated transgenic plants expressing an antisense (AS) copy of the SHY cDNA in pollen. Primary transformants exhibited poor seed set, but homozygous lines could be identified. In these lines, nearly all pollen tubes failed to reach the ovules; tube growth was arrested at the apex of the ovary and the pollen tubes exhibited abnormal callose deposits throughout the tube and in the tips. We show that a SHY::eGFP fusion protein is targeted to the cell wall. The structure of the SHY protein is nearly identical to other extracellular matrix glycoproteins that are composed of LRRs, such as the polygalacturonase inhibitor proteins (PGIP) of plants. PGIPs may function as defense proteins by inhibiting fungal endo-polygalacturonases, but enzyme assays with extracts of AS-SHY pollen do not support such an inhibitor role for SHY. The tomato ortholog of SHY interacts with a tomato receptor kinase (LePRK2) in yeast two-hybrid and pull-down assays (Tang et al., 2002, 2004); this, and the AS-SHY phenotypes, suggest instead that SHY might function in a signal transduction pathway mediating pollen tube growth.

Ancillary