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Letters to Nature

Nature 429, 302-305 (20 May 2004) | doi:10.1038/nature02523; Received 17 December 2003; Accepted 30 March 2004

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

Paja Sijacic1, Xi Wang2,5, Andrea L. Skirpan2, Yan Wang3, Peter E. Dowd2, Andrew G. McCubbin2,5, Shihshieh Huang4 & Teh-hui Kao1,2,3

  1. Integrative Biosciences Graduate Degree Program, The Pennsylvania State University, 403 Althouse Laboratory, University Park, Pennsylvania 16802, USA
  2. Department of Biochemistry and Molecular Biology, The Pennsylvania State University, 403 Althouse Laboratory, University Park, Pennsylvania 16802, USA
  3. Intercollege Graduate Program in Plant Physiology, The Pennsylvania State University, 403 Althouse Laboratory, University Park, Pennsylvania 16802, USA
  4. Mystic Research, Monsanto Company, 62 Maritime Drive, Mystic, Connecticut 06355, USA
  5. Present addresses: Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA (X.W.); School of Biological Sciences and Center for Reproductive Biology, Washington State University, Pullman, Washington 99164, USA (A.G.M.)

Correspondence to: Teh-hui Kao1,2,3 Email: txk3@psu.edu

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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.