Pattern of genotype by environment interaction for radiata pine in southern Australia

Key message: Based on analyses using 20 genetically connected radiata pine trials and on the pattern of trial-trial genetic correlations, current regionalisation of breeding in southern Australia seems justified. However, relationships between environmental variables and genotype by environment interaction are complex.

Context: Current radiata pine breeding and deployment in Australia is based largely on the plantation inventory zones rather than on biological patterns of genotype by environment interaction (G × E), and consequently cannot deliver optimal genetic gains across the whole plantation estate. Aim: This study examined patterns of G × E to facilitate deployment of genetic stock to particular environments.

Methods: We used 20 genetically well-connected trials across southern Australia to obtain estimates of genetic correlations between performances at different trial sites. Extended factor analyses (XFA) were used to estimate G × E variance and produce a matrix of site-site genetic correlations. The patterns among these correlations were examined using a heat map and hierarchical clustering.

Results: The XFA captured a large proportion of both additive and non-additive G × E. Significant G × E for diameter growth can be expected between Tasmania and Mainland, and within Tasmania itself. The study also confirmed presence of G × E between Murray Valley region in New South Wales and the rest of southern Australia.

Conclusion: The G × E interaction at transcontinental scale can be correlated to the climate variables, primarily rainfall and temperature; however, the drivers of G × E may also be related to smaller scale environmental variation