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Strong genetic differences were demonstrated for both resistance to white pine weevil (Pissodes strobi (Peck)) attack and juvenile heightgrowth in an open-pollinated progeny test of interior spruce. This test was a large (139 families), 10-year-old test in south central British Columbia with 8 years of accumulated weevil attack. Individual-tree heritability for genetic resistance was = 0.4. Strong differencesamong families for this resistance was shown by a coefficient of variation of 46%. Besides strong family effects, the source of origin ofparent trees, as indicated by biogeoclimatic zone, was a significanteffect in the model. Individual-tree heritability was also high for juvenile height growth (= 0.5). Although there is a significant positive phenotypic correlation (rp = 0.11) between leader growth and wee il attack (the weevils preferring longer leaders), there is a strong negative genetic correlation (rA = - 0.61) indicating that inherently faster growing families have higher levels of genetic resistance. This high and favorable negative genetic correlation is accompanied by a positive environmental correlation of the same magnitude (rE = 0.46), indicating that environmental effects, which make longer leaders more attractive to the weevils, are independent of the fact that more vigorous families are more likely tohave effective resistance to weevil attack. [ABSTRACT FROM AUTHOR]

In plants, relationships between resistance to herbivorous insect pests and growth are typically controlled by complex interactions between genetically correlated traits. These relationships often result in tradeoffs in phenotypic expression. In this study we used genetical genomics to elucidate genetic relationships between tree growth and resistance to white pine terminal weevil (Pissodes strobi Peck.) in a pedigree population of interior spruce (Picea glauca, P. engelmannii and their hybrids) that was growing at Vernon, B.C. and segregating for weevil resistance. Genetical genomics uses genetic perturbations caused by allelic segregation in pedigrees to co-locate quantitative trait loci (QTLs) for gene expression and quantitative traits. Bark tissue of apical leaders from 188 trees was assayed for gene expression using a 21.8K spruce EST-spotted microarray; the same individuals were genotyped for 384 SNP markers for the genetic map. Many of the expression QTLs (eQTL) co-localized with resistance trait QTLs. For a composite resistance phenotype of six attack and oviposition traits, 149 positional candidate genes were identified. Resistance and growth QTLs also overlapped with eQTL hotspots along the genome suggesting that: 1) genetic pleiotropy of resistance and growth traits in interior spruce was substantial, and 2) master regulatory genes were important for weevil resistance in spruce. These results will enable future work on functional genetic studies of insect resistance in spruce, and provide valuable information about candidate genes for genetic improvement of spruce.