Sexual Plant Reproduction

, Volume 12, Issue 1, pp 6–13 | Cite as

Breakdown of self-incompatibility in a natural population of Petunia axillaris (Solanaceae) in Uruguay containing both self-incompatible and self-compatible plants

  • Tatsuya Tsukamoto
  • T. Ando
  • Hisashi Kokubun
  • Hitoshi Watanabe
  • Masahiro Masada
  • X. Zhu
  • Eduardo Marchesi
  • T. Kao
ORIGINAL PAPER

Abstract

 Many members of the Solanaceae display a type of gametophytic self-incompatibility which is controlled by a single multiallelic locus, called the S-locus. From our previous survey of more than 100 natural populations of Petunia axillaris (a solanaceous species) in Uruguay, we had found that the majority of the populations of subspecies axillaris were comprised of virtually all self-incompatible individuals. The rest were ”mixed populations” which contained mostly self-incompatible and some self-compatible individuals. In this study, we examined the self-incompatibility behavior and determined the S-genotypes of 33 plants raised from seeds obtained from one such mixed population, designated U1. We found that 30 of the 33 plants (designated U1–1 through U1–33) were self-incompatible and a total of 18 different S-alleles were represented. To determine the S-genotypes of the three self-compatible plants (U1–2, U1–16, and U1–22) and the possible causes for the breakdown of their self-incompatibility, we carried out reciprocal crosses between each of them and each of the 18 S-homozygotes (S1S1 through S18S18) obtained from bud-selfed progeny of 14 of the 30 self-incompatible plants. For U1–2 and U1–16, we also carried out additional crosses with U1–25 (with S1S13 genotype) and an S13S15 plant (obtained from a cross between an S13-homozygote and an S15-homozygote), respectively. Based on all the pollination results and analysis of the production of S-RNases, products of S-alleles in the pistil, we determined the S-genotypes of U1–2, U1–16, and U1–22, and propose that the breakdown of self-incompatibility in these three plants is caused by suppression of the production of S13-RNase from the S13-allele they all carry. We have termed this phenomenon ”stylar-part suppression of an S-allele” or SPS.

Key words Petunia axillaris Self-incompatibility Self-compatibility Stylar-part suppression 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • Tatsuya Tsukamoto
    • 1
  • T. Ando
    • 1
  • Hisashi Kokubun
    • 1
  • Hitoshi Watanabe
    • 1
  • Masahiro Masada
    • 1
  • X. Zhu
    • 1
  • Eduardo Marchesi
    • 2
  • T. Kao
    • 3
  1. 1.Faculty of Horticulture, Chiba University, 648 Matsudo, Chiba Prefecture 271–8510, Japan e-mail andot@midori.h.chiba-u.ac.jp Tel. +81-473-63-1221 extension 4311; Fax 81-473-66-1625 extension 2234JP
  2. 2.Facultad de Agronomia, Universidad de la República, Garzón 780, Montevideo, UruguayUY
  3. 3.Department of Biochemistry and Molecular Biology, 403 Althouse Lab, The Pennsylvania State University, University Park, PA 16802, USA e-mail txk3@psu.edu Tel. +1-814-863-1042; Fax 1-814-863-9416US

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