Congratulations to Julia Candotti on becoming the fourth FABIan to successfully complete their PhD studies this year. Julia presented her Prestige Seminar “Haplogenome analysis and genetic dissection of growth and wood property traits in Eucalyptus urophylla x E grandis hybrids” on 26 January. Her PhD supervisors were Prof. Zander Myburg, Prof. Tuan Duong, Prof. Eshchar Mizrachi and Prof. Sanushka Naidoo, along with collaborators Dr Raphael Ployet, Dr Nanette Christie and Dr Marja O’Neill. The examiners for her thesis were Prof. Dario Grattapaglia (EMBRAPA, Brazil), Prof. Gary Peter (University of Florida) and Prof. Rene Vaillancourt (University of Tasmania).

 Prof. Zander Myburg praised Julia for working fast and efficiently and being the student to complete her journey from Honours to PhD in the shortest time in the FMG Programme’s history. Her study identified a locus affecting survival and conferring a growth advantage in hybrid Eucalyptus plantation trees and her PhD is the culmination of a a detailed analysis of the molecular genetics and genomics in a eucalypt hybrid breeding trial.

The aim of Julia’s PhD study was to perform genome-wide characterization of the haplotype and structural diversity in the genomes of E. grandis and E. urophylla parents used for hybrid breeding and to use the haplotypes for genetic dissection in F1interspecific hybrid progeny. Current genetic dissection studies in Eucalyptus, an important genus for the forestry industry, make use of SNP markers, and there is a limited amount of research into the extent of haplotype and structural variant (SV) diversity in Eucalyptus species. 

Julia developed a haplotype-mining panel for Eucalyptus that provides a tool which targets 8 915 target regions at 4 637 genes, that can be used to understand the haplotype diversity present within the genus, analyse genome evolution and provide multi-allelic haplotype markers that can be used for genetic dissection studies.

Her study has improved our understanding of haplotype and SV diversity within E. urophylla and E. grandis parents used for hybrid breeding and has demonstrated how this information can be used to identify candidate genes underlying complex traits. Haplotype markers and parental haplogenomes enabled the identification of a region with fewer than 100 candidate genes underlying a large effect QTL for diameter growth (DBH). Her study hypothesises that this QTL has pleiotropic effects on growth and viability of the hybrid trees in the subtropical environment of Zululand, and she identified several candidates that can be prioritised for future functional genetic studies and molecular breeding efforts.