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Identification of the pollen determinant of S-RNase-mediated self-incompatibility


Many flowering plants have adopted self-incompatibility mechanisms to prevent inbreeding and promote out-crosses1. In the Solanaceae, Rosaceae and Scrophulariaceae, two separate genes at the highly polymorphic S-locus control self-incompatibility interactions: the S-RNase gene encodes the pistil determinant and the previously unidentified S-gene encodes the pollen determinant2,3,4. S-RNases interact with pollen S-allele products to inhibit the growth of self-pollen tubes in the style. Pollen-expressed F-box genes showing allelic sequence polymorphism have recently been identified near to the S-RNase gene in members of the Rosaceae and Scrophulariaceae5,6,7,8; but until now have not been directly shown to encode the pollen determinant. Here we report the identification and characterization of PiSLF, an S-locus F-box gene of Petunia inflata (Solanaceae). We show that transformation of S1S1, S1S2 and S2S3 plants with the S2-allele of PiSLF causes breakdown of their pollen function in self-incompatibility. This breakdown of pollen function is consistent with ‘competitive interaction’, in which pollen carrying two different pollen S-alleles fails to function in self-incompatibility1,9,10. We conclude that PiSLF encodes the pollen self-incompatibility determinant.

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Figure 1: Characterization of PiSLF.
Figure 2: Schematic representation of transformation experiments to ascertain the function of PiSLF.
Figure 3: Analyses of S1S1 transgenic plants carrying PiSLF2 transgene.
Figure 4: Analysis of progeny of an S2S3 transgenic plant, S2S3/PiSLF2-1, carrying a single copy of the PiSLF2 transgene.


  1. 1

    de Nettancourt, D. Incompatibility and Incongruity in Wild and Cultivated Plants (Springer, Berlin, 2001)

    Book  Google Scholar 

  2. 2

    Lee, H.-S., Huang, S. & Kao, T.-h. S proteins control rejection of incompatible pollen in Petunia inflata. Nature 367, 560–563 (1994)

    ADS  CAS  Article  Google Scholar 

  3. 3

    Murfett, J., Atherton, T. L., Mou, B., Gasser, C. S. & McClure, B. A. S-RNase expressed in transgenic Nicotiana causes S-allele-specific pollen rejection. Nature 367, 563–566 (1994)

    ADS  CAS  Article  Google Scholar 

  4. 4

    Kao, T.-h. & Tsukamoto, T. The molecular and genetic bases of S-RNase-based self-incompatibility. Plant Cell advance online publication 9 March 2004 (doi:10.1105/tpc.016154)

  5. 5

    Lai, Z. et al. An F-box gene linked to the self-incompatibility (S) locus of Antirrhinum is expressed specifically in pollen and tapetum. Plant Mol. Biol. 50, 29–42 (2002)

    CAS  Article  Google Scholar 

  6. 6

    Entani, T. et al. Comparative analysis of the self-incompatibility (S-) locus region of Prunus mume: identification of a pollen-expressed F-box gene with allelic diversity. Genes Cells 8, 203–213 (2003)

    CAS  Article  Google Scholar 

  7. 7

    Ushijima, K. et al. Structural and transcriptional analysis of the self-incompatibility locus of almond: identification of a pollen-expressed F-box gene with haplotype-specific polymorphism. Plant Cell 15, 771–781 (2003)

    CAS  Article  Google Scholar 

  8. 8

    Zhou, J. et al. Structural and transcriptional analysis of S-locus F-box (SLF) genes in Antirrhinum. Sex. Plant Reprod. 16, 165–177 (2003)

    CAS  Article  Google Scholar 

  9. 9

    Golz, J. F., Su, V., Clarke, A. E. & Newbigin, E. A molecular description of mutations affecting the pollen component of the Nicotiana alata S locus. Genetics 152, 1123–1135 (1999)

    CAS  PubMed  PubMed Central  Google Scholar 

  10. 10

    Golz, J. F., Oh, H.-Y., Su, V., Kusaba, M. & Newbigin, E. Genetic analysis of Nicotiana pollen-part mutants is consistent with the presence of an S-ribonuclease inhibitor at the S locus. Proc. Natl Acad. Sci. USA 98, 15372–15376 (2001)

    ADS  CAS  Article  Google Scholar 

  11. 11

    McCubbin, A. G., Zuniga, C. & Kao, T.-h. Construction of a binary artificial chromosome library of Petunia inflata and the identification of large genomic fragments linked to the self-incompatibility (S-) locus. Genome 43, 820–826 (2000)

    CAS  Article  Google Scholar 

  12. 12

    Wang, Y. et al. Chromosome walking in the Petunia inflata self-incompatibility (S-) locus and gene identification in an 881-kb contig containing S 2-RNase. Plant Mol. Biol (in the press)

  13. 13

    Ai, Y. et al. Self-incompatibility in Petunia inflata: isolation and characterization of cDNAs encoding three S-allele-associated proteins. Sex. Plant Reprod. 3, 130–138 (1990)

    Article  Google Scholar 

  14. 14

    Wang, Y., Wang, X., McCubbin, A. G. & Kao, T.-h. Genetic mapping and molecular characterization of the self-incompatibility (S-) locus in Petunia inflata. Plant Mol. Biol. 53, 565–580 (2003)

    CAS  Article  Google Scholar 

  15. 15

    Luu, D.-T. et al. Rejection of S-heteroallelic pollen by a dual-specific S-RNase in Solanum chacoense predicts a multimeric self-incompatibility pollen component. Genetics 159, 329–335 (2001)

    CAS  PubMed  PubMed Central  Google Scholar 

  16. 16

    Huang, S., Lee, H.-S., Karunanandaa, B. & Kao, T.-h. Ribonuclease activity of Petunia inflata S proteins is essential for rejection of self-pollen. Plant Cell 6, 1021–1028 (1994)

    CAS  Article  Google Scholar 

  17. 17

    Luu, D.-T., Qin, K., Morse, D. & Cappadocia, M. S-RNase uptake by compatible pollen tubes in gametophytic self-incompatibility. Nature 407, 649–651 (2000)

    ADS  CAS  Article  Google Scholar 

  18. 18

    Qiao, H. et al. The F-box protein AhSLF-S2 physically interacts with S-RNases that may be inhibited by the ubiquitin/26S proteasome pathway of protein degradation during compatible pollination in Antirrhinum. Plant Cell 16, 582–595 (2004)

    CAS  Article  Google Scholar 

  19. 19

    Bai, C. et al. Skp1 connects cell cycle regulation to the ubiquitin proteolysis machinery through a novel motif, the F-box. Cell 86, 263–274 (1996)

    CAS  Article  Google Scholar 

  20. 20

    Skirpan, A. L. et al. Isolation and characterization of kinase interacting protein 1, a pollen protein that interacts with the kinase domain of PRK1, a receptor-like kinase of petunia. Plant Physiol. 126, 1480–1492 (2001)

    CAS  Article  Google Scholar 

  21. 21

    Mu, J.-H., Lee, H.-S. & Kao, T.-h Characterization of a pollen-expressed receptor-like kinase gene of Petunia inflata and the activity of its encoded kinase. Plant Cell 6, 709–721 (1994)

    CAS  Article  Google Scholar 

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We thank A. H. Omeis for the greenhouse work, J. Wang for routine laboratory assistance and the Monsanto Sequencing Facility for sequencing the BAC clones. This work was supported by a Predoctoral Fellowship for Students with Disabilities from the National Institutes of Health (P.E.D.) and by grants from the National Science Foundation (T.-h.K.).

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Correspondence to Teh-hui Kao.

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The authors declare that they have no competing financial interests.

Supplementary information

Supplementary Figure S1

Alignment of the deduced amino acid sequences of three alleles of an S-locus F-box gene of Petunia inflata, named PiSLF. (JPG 184 kb)

Supplementary Figure S2

Schematic of the PiSLF2 construct used in all transformation experiments to generate transgenic plants expressing the PiSLF2 transgene. (JPG 20 kb)

Supplementary Figure Legends (DOC 19 kb)

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Sijacic, P., Wang, X., Skirpan, A. et al. Identification of the pollen determinant of S-RNase-mediated self-incompatibility. Nature 429, 302–305 (2004).

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