Marker-Assisted Selection for Disease Resistance in Loblolly Pine (Pinus taeda, L.)

A set of 906 clonally replicated loblolly pine varieties (Pinus taeda, L.) from 35 full-sib families were assessed for growth, stem form, and disease resistance after 6 growing seasons.  Using a set of more than 5000 SNPs we identified 3340 SNPs that were informative in this population and were subsequently used in genetic analyses.  Resistance to fusiform rust infection caused by Cronartium quercuum (Berk) Miyabe ex Shirai f.sp. fusiforme was heritable (H²=0.44) and significant associations were identified using a Bayes CPi analysis.  The five (5) most significant SNP loci accounted for 45% of the total variance for fusiform rust infection.  When applied to specific full-sib families the highest ranked SNP (p=0.91) reduced family mean disease incidence by as much 35% at specific field trial locations.