title: Early ovule development following self- and cross-pollinations in Eucalyptus globulus Labill. ssp. globulus.
abstract: The study was conducted to identify the self-incompatibility mechanism in Eucalyptus globulus ssp. globulus. Controlled self- and cross-pollinations were conducted on individual flowers from three mature trees that had self-incompatibility levels of 76, 99.6 and 100%. Flowers were harvested at 4, 6 and 8 weeks after pollination. Embryology was investigated by bright field microscopy on material harvested at 4 and 6 weeks after pollination. Fertilization had taken place at 4 weeks after pollination with zygotes and free nuclear endosperm visible. There was a greater proportion of healthy, fertilized ovules in the cross- compared with the self-pollination treatment, and approx. half the ovules examined from both pollen treatments were not fertilized or were degenerating. By 6 weeks after pollination a few zygotes were starting to divide. The number of healthy, fertilized ovules was still greater in the cross-pollination treatment, but the number of healthy fertilized ovules was lower in both treatments compared with 4 weeks after pollination, and many ovules were degenerating. Fertilized ovules were significantly larger than non-fertilized or degenerating ovules and this difference was detectable by eye at 6 and 8 weeks after pollination. The mechanism of self-incompatibility appears to have both late pre- and post-zygotic components.
authors.affiliation: Department of Horticulture, Viticulture and Oenology, Adelaide University, Glen Osmond, South Australia, Australia.
authors.forename: L M
authors.initials: LM
authors.lastname: Pound
authors.forename: M A B
authors.initials: MA
authors.lastname: Wallwork
authors.forename: B M
authors.initials: BM
authors.lastname: Potts
authors.forename: M
authors.initials: M
authors.lastname: Sedgley
mesh_terms: D000465:Algorithms; D048429:Cell Size / Q000502:physiology; D005052:Eucalyptus / Q000196:embryology / Q000502:physiology*; D005298:Fertility / Q000502:physiology; D018547:Plant Stems / Q000502:physiology*; D011058:Pollen / Q000502:physiology*; D012639:Seeds / Q000254:growth & development*; D013997:Time Factors