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Using genetics to plan for native carbon plantings

CRCF affiliated PhD student, Archana Gauli (UTAS) is studying genetic variation and adaptation in cabbage gum (Eucalyptus pauciflora).  This species is being studied because it has been identified as a key species for use in biodiverse carbon plantings in the drier, colder regions of Tasmania. Archana’s project involves the study of: (i) a large genetics trial of E. pauciflora established near Bothwell in Central Tasmania (Dungrove) comprising families and provenances from across the species’ geographic range in southeastern Australia; (ii) seedling morphology of the same families/provenances growing in the glasshouse at the School of Plant Science, University of Tasmania; and (iii) molecular genetic variation and outcrossing rates in the species.  The field trial aims to provide information to improve the design of plantings for long-term maintenance of biodiversity and carbon storage.  This specific project will determine the importance of genetic considerations to this objective, including whether local seed is best, the geographic range across which seed can be considered “local”, and the extent to which survival, health and growth can be predicted from factors such as the level of inbreeding and climatic parameters at the site of seed collection.

The Dungrove genetic field trial of Eucalyptus pauciflora that Archana is studying as part of her PhD. (Image: Archana Gauli)

The pedigreed field trial includes 281 Tasmanian families from 37 provenances and seed bulks from 15 provenances from Victoria, ACT and NSW.  The seedlots were planted in a randomised incomplete block design with eight replicates, each comprising 400 plants. The trial was established in September 2010.  Archana has subsequently monitored seedling height as well as insect and animal damage. She will continue to monitor performance and health of the seedlings on a periodic basis throughout her PhD. One or two field trials using the same seedlots are expected to be planted by the ARC Linkage grant partners this spring and, if successful, will allow Archana to study genotype by environment interactions for the above traits.

Archana spent most of last summer assessing genetic variation in the morphology of the glasshouse-grown seedlings of E. pauciflora. This trial also includes some seedlings of E. tenuiramis, as this species is believed to be one of the main species that hybridises with E. pauciflora.  Because the seed used in the study was collected from open-pollinated flowers (i.e., the pollen parent is unknown), it is important to monitor the seedlings for signs of hybridisation.  After growing seedlings for six months, 38 different morphomertic traits were scored.  Data analysis is ongoing and Archana feels that when it is completed she will observe some interesting patterns of genetic variation in the seedling morphology from different provenances.

Archana has also been working in the molecular laboratory at UTAS, extracting DNA from leaf samples collected from the field trial.  Over the next twelve months she aims to extract DNA from 1759 samples!  Such a big study will require meticulous sample handling, labelling, storage and data management.  Archana plans to use selectively neutral genetic markers (microsatellites) to examine the underlying the genetic/evolutionary relationships among the different provenances of E. pauciflora and to determine outcrossing and inbreeding rates.  These data will allow her also to assess the role that environmental selection plays in producing the morphological differences that we see among the different provenances of E. pauciflora.

Biobuzz issue fourteen, May 2011