Vol. 84 No: 2

Title:
Evidence for the occurrence of unreduced gametes in interspecific hybrids of Hibiscus

Authors:
K. VAN LAERE, A. DEWITTE, J. VAN HUYLENBROECK and E. VAN BOCKSTAELE

pp: 240-247

Abstract:
Interspecific crosses within Hibiscus resulted in F₁ and F₂ (self-pollination of F₁) progeny of H. syriacus × H. paramutabilis. Of these populations, seven F₁ and five F₂ hybrids were analysed for the occurrence of unreduced gametes. Pollen from H. syriacus, H. paramutabilis, and the F₁ and F₂ hybrids had diameters between 80 – 230 μm. However, two of the F₂ hybrids tested also had a few pollen grains (< 1%) with a diameter of 250 μm. Flow cytometry and a study of meiosis in the pollen of these two F₂ hybrids revealed that 6 – 10% unreduced pollen was produced. Both the parent plants, H. syriacus ‘Oiseau Bleu’ and H. paramutabilis, and all of the F₁ hybrids were tetraploid, with a genome size between 2.32 – 2.48 pg 1C^-1. However, all five F₂ hybrids were hexaploid, with a genome size between 3.49 – 3.59 pg 1C^-1. Since no unreduced pollen could be detected in the F₁ H. syriacus × H. paramutabilis hybrids, either by flow cytometry or by a study of meiosis in the pollen, it could be concluded that the F₁ hybrids must produce unreduced egg cells.

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