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

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.

Overcoming physiological dormancy in seeds of Triodia (Poaceae) to improve restoration in the arid zone

“…palea and lemma) were removed, with four species germinating greater than 70%. Although technically challenging to remove the covering structures without damaging the embryo, this approach can been adapted for the propagation of large numbers of Triodia , as in other Poaceae (Adkins et al ; Meissner ; Wells & Dixon ; Gallart et al ; Ma et al ; Farley et al ). It is most likely that the covering floret structures inhibit germination though restricting the growth of the embryo.…”

“…The reestablishment of Triodia hummocks in disturbed lands after mining has been a focus of restoration practitioners for decades, with limited success (Johnson & Putwain ; Morrison et al ). Numerous technical reports have identified a multitude of issues surrounding the reestablishment of Triodia species from seed (Jacobs ; Atkins ; Adkins et al ; Meissner ; Wells & Dixon ; Wells et al ). Some of the challenges identified include the sourcing of sufficient quantities of germinable seed due to low fecundity and the sporadic nature of seeding events in arid systems (Jacobs ; Westoby et al ; Wright et al ), and the erratic germination achieved when seeds are sown at restoration sites.…”

“…Erratic germination in seeds of Triodia has been variously attributed to intra‐specific or ecotypic differences, biotic and abiotic effects on dormancy, varying responses to germination promoting compounds such as gibberellic acid (GA 3 ), NO 3 , and smoke‐water, and differing experimental methodologies between studies (Adkins et al ; Meissner ; Wells & Dixon ; Armstrong & Legge ). So far, the highest germination reported for any Triodia species is 95% for Triodia longiceps seeds that were incubated at 30°C after removal of the covering floret (palea and lemma) structures and treatment of the seeds with a 5% smoke‐water solution (Adkins et al ).…”

Local provenance in rehabilitation of degraded landscapes: a case study from the Hawkesbury–Nepean catchment, Australia

“…Wilkinson 2001). One of the goals of the Convention on Biological Diversity (Anonymous 1992), ratified by some 180 countries, includes genetic diversity, but understanding its importance in the long‐term maintenance of diversity has been limited (Wells et al . 2003).…”

“…Keller et al 2000; Jones et al 2001; Peuke et al . 2002; Wells et al . 2003), and therefore the precautionary approach is desirable when information on a specific taxon is unavailable.…”