Protogyny, Self-Incompatibility and Pollination in Anthocercis gracilis (Solanaceae)

Abstract

The pollination biology of A. gracilis was examined in glasshouse plants and natural populations. The species is both protogynous and pre-zygotically self-sterile (self-incompatible). Protogyny prevents autopollination (autogamous self-pollination), and self-incompatibility avoids geitonogamous self-fertilisation. This sequence is essential because prior selfing blocks the style with pollen tubes and prevents subsequent outcrossing. Flowers have no discernible daytime odour, the pollen is clumped and not easily shaken from opened anthers, and daytime insect visitors are rarely observed in the field. However in long-established populations, most plants carry one or a few capsules during winter-spring and seeds per capsule are generally high. Reproduction of natural populations involves reliable pollinators of unknown identity, possibly small flies, bees or moths lured by a tiny amount of sucrose-rich nectar secreted by the hypogynous disc. It is not anomalous that A. gracilis has two devices for preventing self-fertilisation, protogyny and strong self-incompatibility, as both are functional aspects of the same outcrossing system. This is the first report of self-incompatibility in the Anthocercideae which is an old and apparently basal lineage in the Solanaceae.

The effect of small population size on the mating system of a rare clonal mallee, Eucalyptus argutifolia (Myrtaceae)

“…As this study only assessed self-compatibility to the stage of pollen tube penetration of the ovule, we cannot discount later-acting prezygotic control of the breeding system in E. argutifolia, as has been recorded in species from other plant families ( e.g. Kenrick & Knox, 1985;Stace, 1995). It should be noted, however, that studies investigating early seed development in Eucalyptus have found no evidence of self-incompatibility operating between the stages of pollen tube penetration of the ovule and fertilization (Sedgley, 1989;.…”

Corrigendum to: A threatened ecological community: research advances and priorities for Banksia woodlands

“…Other taxa have received less research attention (e.g. Stace 1995;Monks 1999;Close et al 2006;Nield et al 2009), with some threatened species, such as Tetraria australiensis C.B. Clarke (a perennial, tufted sedge) having no published biological information.…”