A molecular approach to provenance delineation for the restoration of hummock grasslands (Triodia spp.) in arid-tropical Australia

Authors

  • Grant Wells,

  • Grace Zawko,

  • Maurizio Rossetto,

  • Kingsley Dixon


  • *. The project was funded by Argyle Diamonds Pty Ltd as part of a study to restore endemic hummock grasses to post-mine sites and supported the authors research into the conservation genetics of Australian flora.

Abstract

Summary Studies were undertaken to develop genetic principles for the restoration of spinifex grasses (Triodia spp.) at the Argyle Diamond Mines in northern Australia. The study used random amplified polymorphic DNA (RAPD) DNA markers to provide a molecular delineation of provenance boundaries for two species Curly Spinifex (Triodia bitextura) and Triodia bynoei and to provide measures which ensure replacement of local genetic diversity. Within-population diversity measures (0.44 ± 0.03 T. bitextura and 0.32 ± 0.04 T. bynoei) and the proportion of diversity attributed to between-population differences (≈ 12%) by analysis of molecular variance (AMOVA) indicate extensive out-crossing in these seeder species. As such, both species should be restored using seed-based methods to maintain natural diversity. Significant groups of populations (P < 0.05) identified by AMOVA correspond directly to clustering of populations in a dendogram drawn using UPGMA, indicating significant provenances in both species. For T. bitextura, a significant genotypic variation identified at 60 km from mine populations was not evident at 30 km. Seed for restoration at the mine should, therefore, be harvested from within 30 km of the area to be restored to ensure maintenance of the local provenance. Two T. bynoei populations located 2 km apart were found to represent a single genotype, all other populations were identified as separate genotypes. The majority of the isolated T. bynoei populations, therefore, represent distinct provenances. For both species, in excess of 80% of the measured species diversity occurred in just 20 individuals. As restoration of these grasses will necessitate harvesting seed from thousands of plants the species capacity for evolutionary change should be maintained. With continuing improvements in the effectiveness of molecular genetics technology, the assessment of provenance boundaries through the use of genetic markers is becoming a realistic option for the development of more genetically representative sourcing of genotypes in plant restoration programmes.

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