Changes in total height of <i>Pinus pinaster</i> seedlings.

<p>Seedlings were derived from 10 maternal genotypes clonally replicated in two contrasting maternal environments, one favourable (open circles) and one unfavourable (black circles) for pine growth and reproduction (N = 720). Least square means obtained from the mixed models excluding (A) and including (B) seed mass as a covariate are shown.</p

Necrosis length of <i>Pinus pinaster</i> seedlings caused by inoculation treatments.

<p>Seedlings were derived from 10 maternal genotypes clonally replicated in two contrasting maternal environments, one favourable (open circles) and one unfavourable (black circles) for pine growth and reproduction, four weeks after inoculation with the <i>Fusarium circinatum</i> pathogen (Inoculated) or mock inoculation with distilled sterile water (Control) (N = 360). Least square means ± standard errors obtained from the mixed models excluding (A) and including (B) seed mass as a covariate are shown.</p

Environmental Maternal Effects Mediate the Resistance of Maritime Pine to Biotic Stress

<div><p>The resistance to abiotic stress is increasingly recognised as being impacted by maternal effects, given that environmental conditions experienced by parent (mother) trees affect stress tolerance in offspring. We hypothesised that abiotic environmental maternal effects may also mediate the resistance of trees to biotic stress. The influence of maternal environment and maternal genotype and the interaction of these two factors on early resistance of <i>Pinus pinaster</i> half-sibs to the <i>Fusarium circinatum</i> pathogen was studied using 10 mother genotypes clonally replicated in two contrasting environments. Necrosis length of infected seedlings was 16% shorter in seedlings grown from favourable maternal environment seeds than in seedlings grown from unfavourable maternal environment seeds. Damage caused by <i>F. circinatum</i> was mediated by maternal environment and maternal genotype, but not by seed mass. Mechanisms unrelated to seed provisioning, perhaps of epigenetic nature, were probably involved in the transgenerational plasticity of <i>P. pinaster</i>, mediating its resistance to biotic stress. Our findings suggest that the transgenerational resistance of pines due to an abiotic stress may interact with the defensive response of pines to a biotic stress.</p></div

Results of the general linear mixed model for analysis of the <i>Pinus pinaster</i> seedlings height 18 months after sowing.

<p>Seedlings were derived from 10 maternal genotypes clonally replicated in two contrasting maternal environments, one favourable and one unfavourable for pine growth and reproduction. Analyses excluding and including individual seed mass as a covariate are shown. Degrees of freedom (DF) and <i>F</i>-ratios of fixed factors, and variance components (VarComp) and associated χ² of random factors are shown. Significance (<i>P</i> value) is indicated in bold (<i>P</i><0.05).</p>a<p>Block was nested within maternal environment and cone was nested within ramet.</p

Results of the general linear mixed model for analysis of the <i>Pinus pinaster</i> seedlings necrosis length.

<p>Seedlings were derived from 10 maternal genotypes clonally replicated in two contrasting maternal environments, one favourable and one unfavourable for pine growth and reproduction, four weeks after inoculation with the <i>Fusarium circinatum</i> pathogen or mock inoculation with distilled sterile water. Analyses excluding and including individual seed mass as a covariate are shown. Interaction terms I×E and I×G account for maternal effects and genetic variation, respectively, in seedling resistance to the pathogen, whereas the I×G×E interaction accounts for genetic variation in transgenerational responses. Degrees of freedom (DF) and <i>F</i>-ratios of fixed factors, and variance components (VarComp) and associated χ² of random factors are shown. Significance (<i>P</i> value) is indicated in bold (<i>P</i><0.05).</p>a<p>Block was nested within maternal environment and cone was nested within ramet.</p>b<p>Tray was nested within inoculation treatment.</p