Quambalaria shoot blight resistance in marri (Corymbia calophylla) : genetic parameters and correlations between growth rate and blight resistance

Quambalaria shoot blight (QSB) has emerged recently as a severe disease of Corymbia calophylla (marri). In this study, QSB damage and growth were assessed in Corymbia calophylla trees at 4 and 6 years of age in two common gardens consisting of 165 and 170 open-pollinated families representing 18 provenances across the species’ natural distribution. There were significant differences between provenances for all traits. The narrow-sense heritability for growth traits and QSB damage at both sites were low to moderate. The genetic correlation between QSB damage and growth traits was negative; fast-growing families were less damaged by QSB disease. Age-age genetic correlations for individual traits at four and six years were very strong, and the type-B (site–site) correlations were strongly positive for all traits. Provenances from cooler wetter regions showed higher resistance to QSB. The QSB incidence at 6 years was significantly correlated with environmental factors of the provenance’s origin. The QSB incidence at years four and six was not correlated with the QSB expression in 3-month-old seedlings. Based on these results, selection for resistance could be undertaken using 4-year-old trees. There is potential for a resistance breeding program to develop populations of marri genetically diverse and resistant to QSB.Open Access funding by CAUL and its Member Institutions. PhD scholarship between the Vietnamese Government and Murdoch University as well as the Australian Research Council Linkage Program.https://link.springer.com/journal/11295am2023Forestry and Agricultural Biotechnology Institute (FABI)BiochemistryGeneticsMicrobiology and Plant Patholog