Biodiv Sci ›› 2010, Vol. 18 ›› Issue (2): 120-128.DOI: 10.3724/SP.J.1003.2010.125

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Detection of interspecific introgressive hybridization in Liriodendron with EST-SSR markers

Honglian Zhang; Huogen Li*   

  1. Key Laboratory of Genetics & Biotechnology, Nanjing Forestry University, Ministry of Education, Nanjing 210037
  • Received:2009-09-25 Online:2010-03-20 Published:2010-03-20
  • Contact: Huogen Li

Abstract:

Gene introgression usually results from spontaneous hybridization among closely related exotic and native species, and thus can significantly impact the genetic structure of native species, especially on en-dangered species. It is believed that no interspecies reproductive barriers exist within Liriodendron spp. The endangered status of Liriodendron chinense in China is compounded by the potential risk of interspecific in-trogressive hybridization resulting from the frequent introduction of L. tulipifera and by the extensive plant-ing of hybrid Liriodendron within the past decade. Here, we report a possible trend of interspecific introgres-sive hybridization in the genus Liriodendron. We sampled five mixture plantations with L. chinense, L. tuli-pifera, and hybrid Liriodendron from southeastern China. In each plantation, 19–130 adults and 60–117 na-turally regenerated seedlings or open-pollinated progeny were sampled. The mating pattern of Liriodendron was examined using parentage analysis based on 11 EST-SSR loci, and the extent of introgressive hybridiza-tion was estimated in terms of an introgression coefficient derived from parentage-offspring regression coef-ficients of allele frequencies. We found evidence of interspecific introgressive hybridization in all five planta-tions of Liriodendron, although the orientation and extent of gene introgression differed among plantations. Furthermore, for any species, we found that the extent of gene introgression was positively related to its pop-ulation size. Herein, we present conservation strategies for Liriodendron chinense in the context of our re-sults.