Figure 1

From: Microbiome and infectivity studies reveal complex polyspecies tree disease in Acute Oak Decline

Figure 1

Symptoms of AOD observed in the field (ad), reproducing the symptoms of AOD through log inoculations with combinations of bacteria and Agrilus larvae associated with AOD (el), and statistical analysis of lesion formation in log inoculations (mn). (a) Stem bleeds symptomatic of AOD on a mature Quercus robur in the field. (b) Close up view of stem bleeds and bark cracks characteristic of AOD. (c) Cross-section through AOD stem bleeds, showing degradation of vascular tissue (red arrow). (d) Longitudinal section through an AOD stem bleed showing the association between bacterial lesions (blue arrow) and Agrilus biguttatus galleries (red arrow). (e) Wound response in the innerbark of the control treatment (inoculation of a wound with sterile water) of log inoculation trials. (f) Lesion formed in the innerbark of oak logs inoculated with Brenneria goodwinii in log inoculation trials. (g) Lesion formed in the innerbark of oak logs inoculated with Gibbsiella quercinecans in log inoculation trials. (h) Lesion formed in the innerbark of oak logs inoculated with a combination of B. goodwinii and G. quercinecans in log inoculation trials. (i) Wound response in the innerbark of the A. biguttatus treatment (inoculation of a wound with live eggs of A. biguttatus). Note the wound response (blue arrow) and clean gallery created by a larva (red arrow). (j) Lesion formed in the innerbark of oak logs inoculated with B. goodwinii and eggs of A. biguttatus. Note the lesion developing from the inoculation point (blue arrow) and from the galleries (red arrow). (k) Lesion formed in the innerbark of oak logs inoculated with G. quercinecans plus eggs of A. biguttatus. Note the lesion developing from the inoculation point (blue arrow) and from the galleries (red arrow). (l) Lesion formed in the innerbark of oak logs inoculated with B. goodwinii, G. quercinecans plus eggs of A. biguttatus. Note the lesion developing from the inoculation point (blue arrow) and from the galleries (red arrow). (m) Mean lesion area formed in the inner bark of logs inoculated with bacteria. Colour indicates statistical significance (see key). The bacterial species inoculated were back-isolated in fulfilment of Koch’s fourth postulate. Error bars=−s.e. (n) Mean lesion area formed in the inner bark of logs inoculated with bacteria and A. biguttatus eggs. Colour indicates statistical significance (see key in panel (m)). The bacterial species inoculated were back-isolated in fulfilment of Koch’s fourth postulate. EbErwinia billingiae, BgBrenneria goodwinii, GqGibbsiella quercinecans. Error bars=−s.e.