Early selection for resistance to Heterobasidion parviporum in Norway spruce is not likely to adversely affect growth and wood quality traits in late-age performance

Abstract

Infections with Heterobasidion parviporum devalue the Norway spruce timber as the decayed wood does not meet the necessary quality requirements for sawing. To evaluate the incorporation of disease resistance in the Norway spruce breeding strategy, an inoculation experiment with H. parviporum on 2-year-old progenies of 466 open-pollinated families was conducted under greenhouse (nursery) conditions. Lesion length in the phloem (LL), fungal growth in sapwood (FG) and growth (D) were measured on an average of 10 seedlings for each family. The genetic variation and genetic correlations between both LL, FG and growth in the nursery trial and wood quality traits measured previously from 21-year old trees in two progeny trials, including solid-wood quality traits (wood density, and modulus of elasticity) and fiber properties traits (radial fiber width, tangential fiber width, fiber wall thickness, fiber coarseness, microfibril angle and fiber length). For both LL and FG, large coefficients of phenotypic variation (> 26%) and genetic variation (> 46%) were detected. Heritabilities of LL and FG were 0.33 and 0.42, respectively. We found no significant correlations between wood quality traits and growth in the field progeny trials with neither LL nor FG in the nursery trial. Our data suggest that the genetic gains may reach 41 and 52% from mass selection by LL and FG, respectively. Early selection for resistance to H. parviporum based on assessments of fungal spread in the sapwood in nursery material, FG, will not adversely affect growth and wood quality traits in late-age performance.

Pinus sylvestris Breeding for Resistance against Natural Infection of the Fungus Heterobasidion annosum

“…[8,15,[32][33][34][35][36][37], moreover the genetic component in the resistance of Scots pine has also been previously detected [10]. The narrow-sense heritability (h 2 = 0.37) for RotResist was similar or higher to the indices estimated for H. parviporum lesion length in the phloem (0.17 < h 2 < 0.33) and fungal growth in sapwood (h 2 = 0.42) in Norway spruce open-pollinated progenies [9,37]. Also, for Norway spruce clones, moderate broad-sense heritability (H 2 = 0.21) has been estimated for lesion length [15].…”

“…Overall, fungal growth and lesion length in the phloem were not found to correlate with growth and wood quality traits in a study evaluating the incorporation of resistance to H. parviporum in the Norway Spruce Breeding Program [9]. The rather weak, yet significant, positive correlations between family breeding values of RotResist and StVol (Table 2) might be explained by reduced growth among more infected families.…”

“…The biology of the pathogen has been studied intensively [6], nevertheless host genotypes with total resistance to root rot have not been observed for Scots pine or Norway spruce [7]. Considerable effort has been made to study genetic control of root-rot resistance in Norway spruce [8,9]. However, in context of changing climate, Scots pine must also be given a high priority.…”

“…Incorporation of root rot resistance into the selection criteria-e.g., index selection [19]-alongside genetic gains of economically important traits, such as tree height and stem volume, may represent a viable strategy to increase net genetic improvement [20]. For Norway spruce, early selection for resistance to H. parviporum observed not to have negative effect on growth and wood quality later [9]. However, an additional trait in the selection criteria reduces the gains on already included traits [18].…”

Root Rot Resistance Locus PaLAR3 Is Delivered by Somatic Embryogenesis (SE) Pipeline in Norway Spruce (Picea abies (L.) Karst.)

“…The Norway spruce genome harbors genetic variability in root rot resistance which could be utilized in breeding for more resistant forest regeneration material [4]. Lind et al [5] detected 13 quantitative trait locus (QTL) regions in the Norway spruce genome controlling resistance to Heterobasidion parviporum.…”