My primary research interest is the genetic control of growth and development in trees with a focus on wood

formation in Eucalyptus and pine species. Most commercially important phenotypes are quantitative in nature and

affected by hundreds of genes throughout the genome. Genome-wide DNA marker analysis has proven to be a powerful tool

for tracking this genetic variation and developing predictive models of the breeding values of individual trees. By adding 

molecular traits such as gene expression and metabolite variation, we can gain further biological insight into the molecular

basis of complex trait variation. This forms the basis of systems genetics approaches combining the power of population

genetics and systems biology (multi-level ‘omics) analyses to understand the nature of genetic variation affecting wood

formation in tree breeding populations. My group has successfully used this approach in an interspecific backcross

population of E. grandis x E. urophylla to map key genomic regions affecting gene expression and metabolic profiles

associated with variation in growth and wood chemistry.

 

 

The systems genetics data is a rich source for identifying genes and pathways influencing wood property traits. In the past two years we embarked on an effort

to engineer cell wall traits such as xylan content and structure affecting pulp yield employing new approaches such as CRISPR-Cas9 genome editing. Over the

past four years we have successfully used a single nucleotide polymorphism (SNP) marker chip with 60,000 DNA markers to genotype over 3000 Eucalyptus trees

from E. grandis, E. dunnii, E. urophylla, E. nitens and E. grandis x E. urophylla hybrids. This has provided us with unprecedented resolution to rapidly dissect

complex traits in Eucalyptus and develop predictive models for genomic selection of growth and wood properties. We are now working with industry partners to

design the best approaches to validate and integrate these approaches into tree breeding programmes. With support from the Forestry Sector Innovation Fund

(FSIF) we have expanded this work to other Eucalyptus and pine tree species and we are constructing a Genome Diversity Atlas for Eucalyptus and pine species

grown in South Africa. We are working with an international consortium of pine genomics researchers towards generating a multi-species SNP genotyping chip for

tropical pines, on par with what is available for Eucalyptus. These resources will be useful for genetic resource management and molecular breeding of pines.

 

The project lays the foundation for the emerging field of landscape genomics, which combines population genomics with analysis of interactions with environmental

factors including biotic and abiotic stresses to predict tree genotypes that are best adapted to such environments, or that can be deployed to combat new biotic

challenges such as pests and diseases. Over the past two years we initiated the first phase of a landscape genomics study for Eucalyptus grandis and we have

made significant progress towards the aim of mapping the genomic variation available for this species in South Africa and in its natural range in Australia. We have

also, in collaboration with Creation Breeding Innovations (CBI, Dr Steve Verryn), developed an online forest molecular genetics resource (Bioplasm) that aims to

make the extensive DNA fingerprinting and genome-wide diversity created in FMG accessible to researchers and breeders of participating forestry industry

partners.