Balancing selection in wood formation genes of Eucalyptus: E. pilularis diversity pool (n=30)

Single Nucleotide Polymorphisms (SNPs) shared between subgenera (trans-subgeneric SNPs) can be of adaptive importance and persist in separate lineages due to balancing selection. Within three Eucalyptus species pools (n=30), amplicon sequencing identified 6,852 SNPs in 34 candidate wood formation genes. In pairwise comparisons between species from the Monocalyptus and Symphyomyrtus subgenera, 20-23% of SNPs were shared. Primary signatures of balancing selection were high proportions of trans-subgeneric SNPs in functional sequence types, and ten genes with high proportions of trans-subgeneric SNPs and high nucleotide diversities. This unexpectedly large number of trans-subgeneric SNPs demonstrates that balancing selection is abundant in wood formation genes, conferring resilience to abiotic and biotic stresses across divergent subgenera of Eucalyptus.