Embryological Processes and Seed Development in Wollemi pine

A project undertaken at The Royal Botanic Gardens Sydney, and supervised by C Offord

Background

The Wollemi pine was discovered in August 1994 and has been described as the 'Botanical find of the century' (Professor Carrick Chambers).  Wollemia is a monotypic genus known previously only from fossil records.  It shares some of the characteristics of other extant Araucariaceae genera, Agathis and Araucaria but has some unique features.  Low seed set is a feature this species shares with other Araucariaceae but the research on Araucaria and Agathis reproductive biology indicates that there are complex reasons for this phenomenon that may only be understood by studying embryological and seed development.  

The general phenology of the Wollemi pine has been described through field observations (Offord et al. 1999) but the poor seed set of the species in the wild is still unexplained. Studies of embryological and seed development in the laboratory will greatly assist our understanding of reproductive biology in the Wollemi pine. This may impact on the management of the species in the wild and in addition such work will contribute to our understanding of the evolution and taxonomic relationships of this intriguing species.

Practical objectives
  • Understand the causes for low seed set of Wollemi pine and the cyclical nature of pollen and seed cone development
  • Develop a basis of knowledge for management of in situ and ex situ populations of Wollemi pine and enhance seed development potential
  • Understand embryological develop as a basis for development of somatic embryogenesis techniques that may allow  rapid propagation
  • Further identify the botanical features of this species
Main activities March 2002-September 2002

Embryological study: Collected samples of reproductive structures (male cones and female cones) which were dissected under a stereomicroscope. A total of over 1200 microslides have been prepared in the past few months covering stages in the formation of microspores (microspore mother cells, meiosis, mature pollen grains) and the female gametophyte (a few stages in megasporogenesis and one advanced female gametophyte). Isolated stages of embryo development were identified in a microscopic examination. An attempt is being made to make the study as comprehensive as it can be within the limitations of paucity of material of continuous developmental stages.

Phenology study: Two visits to the site were made to obtain large format photographic records of pollen and seed cone production.  Sampling of five separate groups of trees is being conducted.  The images have been scanned and these are used to count the pollen and seed cones produced on the different trees and the position of the cones on the trees.  This information will be compared over time to establish the cycle of pollen and cone production.  Even in the early stage of this investigation we have found interesting information on the position of the different cones within a tree and the early indication that there are widely different production rates across the five tree sample

List of Other Participating Staff

Dr N. Prakash, Associate Professor of Botany, School of Environmental Sciences & Natural Resources Management, University of New England, Armidale NSW

Ms Kerri Clarke, School of Environmental Sciences & Natural Resources Management, University of New England, Armidale

Patricia Meagher, Conservation and Horticulture Research, Mount Annan Botanic Garden, Mount Annan NSW

Mr Jaime Plaza, Photographer, Royal Botanic Gardens Sydney

References

A list of scientific papers and general articles are available from the Royal Botanic Garden Sydney website on the Wollemi pine.

Web site

http://www.rbgsyd.nsw.gov.au/HTML/WOLLEMI/FurtherReading.html

 

Wollemi pine canopy showing terminal cones

Wollemi pine ovule

Wollemi pollen cone after pollen release and seed cones