Early infection by <i>Phytophthora agathidicida</i> up‐regulates photosynthetic activity in <i>Agathis australis</i> seedlings

D'Souza, Kimberley D.; Scott, P. M.; Williams, N.; Bellgard, Stanley E.; Bader, Martin K.‐F.

doi:10.1111/efp.12680

Cited by 2 publications

(1 citation statement)

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“…Indeed, trees infected with P. plurivora showed increased rates of net photosynthesis compared to those infected with P. cactorum during the growing season following the inoculation, despite the differences being not significant in all measurement days ( Ďurkovič et al., 2021 ). To this regard, it has been suggested that infected tissues can act as a carbon sink, altering plant resource allocation patterns, which can be compensated by increased photosynthetic rates ( Pagán and García-Arenal, 2018 ; Berezovska et al., 2021 ; D’Souza et al., 2021 ). In fact, several carbohydrates, including sucrose, showed an increased concentration in areas surrounding the necrotic tissues ( Figure 6 ).…”

Section: Discussionmentioning

confidence: 99%

Defense mechanisms promoting tolerance to aggressive Phytophthora species in hybrid poplar

et al. 2022

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Poplars are among the fastest-growing trees and significant resources in agriculture and forestry. However, rapid growth requires a large water consumption, and irrigation water provides a natural means for pathogen spread. That includes members of Phytophthora spp. that have proven to be a global enemy to forests. With the known adaptability to new hosts, it is only a matter of time for more aggressive Phytophthora species to become a threat to poplar forests and plantations. Here, the effects of artificial inoculation with two different representatives of aggressive species (P. cactorum and P. plurivora) were analyzed in the proteome of the Phytophthora-tolerant hybrid poplar clone T-14 [Populus tremula L. 70 × (Populus × canescens (Ait.) Sm. 23)]. Wood microcore samples were collected at the active necrosis borders to provide insight into the molecular processes underlying the observed tolerance to Phytophthora. The analysis revealed the impact of Phytophthora on poplar primary and secondary metabolism, including carbohydrate-active enzymes, amino acid biosynthesis, phenolic metabolism, and lipid metabolism, all of which were confirmed by consecutive metabolome and lipidome profiling. Modulations of enzymes indicating systemic response were confirmed by the analysis of leaf proteome, and sampling of wood microcores in distal locations revealed proteins with abundance correlating with proximity to the infection, including germin-like proteins, components of proteosynthesis, glutamate carboxypeptidase, and an enzyme that likely promotes anthocyanin stability. Finally, the identified Phytophthora-responsive proteins were compared to those previously found in trees with compromised defense against Phytophthora, namely, Quercus spp. and Castanea sativa. That provided a subset of candidate markers of Phytophthora tolerance, including certain ribosomal proteins, auxin metabolism enzymes, dioxygenases, polyphenol oxidases, trehalose-phosphate synthase, mannose-1-phosphate guanylyltransferase, and rhamnose biosynthetic enzymes. In summary, this analysis provided the first insight into the molecular mechanisms of hybrid poplar defense against Phytophthora and identified prospective targets for improving Phytophthora tolerance in trees.

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Section: Discussionmentioning

confidence: 99%

Defense mechanisms promoting tolerance to aggressive Phytophthora species in hybrid poplar

et al. 2022

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The threat of a major tree pathogen to forest soil mesofauna food webs and ecosystem functioning

Struijk,

Stavert,

Le Grice

et al. 2024

Front. Ecol. Evol.

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Tree pathogens threaten the survival of many forest foundation tree species worldwide. However, there is limited knowledge of how dieback of foundation tree species may threaten other components of forest ecosystems, such as soil biodiversity and associated ecosystem functions. Kauri (Agathis australis), threatened by the root-borne pathogen Phytophthora agathidicida, are culturally and ecologically significant tree species that exert great influence on soil properties. We aimed to characterise soil mesofauna community structure and energy fluxes in kauri forests and assess the potential threat that tree pathogens such as P. agathidicida pose to belowground ecosystems. We sampled soil mesofauna communities and identified specimens to functional feeding groups at 24 pairs of kauri and adjacent broadleaf trees in sites across the Waitākere Ranges Regional Park, Aotearoa – New Zealand. We attributed kauri canopy health scores, measured tree diameter, slope, forest floor depth, and soil carbon dioxide efflux. We also analysed soil samples for P. agathidicida presence, total carbon, and total nitrogen. We constructed soil mesofauna food webs associated with kauri and broadleaf trees, and assessed the uniqueness of food webs associated with kauri and the impacts of P. agathidicida on density, biomass, mean body mass, and energy fluxes of mesofauna taxonomic and trophic groups. We found omnivores with larger body mass at kauri where P. agathidicida was detected (i.e., P. agathidicida-positive soils). Compared to broadleaf trees, mesofauna density and biomass were lower in soils under kauri, and body masses of Symphyla and omnivores were smaller in soils under kauri. Differences in mesofauna community response variables between tree types were mainly modulated by the soil C:N ratio, which had positive effects under broadleaf and neutral to negative effects under kauri. Energy fluxes to detritivores and fungivores were greater under larger trees, regardless of tree type or P. agathidicida detection status. Our findings suggest that kauri support soil mesofauna food webs that are distinctly different from those found under broadleaf trees in the same habitat. A decreased presence of this foundation species may be linked to future impacts on soil mesofauna in this forest ecosystem with increasingly advanced stages of kauri dieback.

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Early infection by Phytophthora agathidicida up‐regulates photosynthetic activity in Agathis australis seedlings

Cited by 2 publications

References 29 publications

Defense mechanisms promoting tolerance to aggressive Phytophthora species in hybrid poplar

Defense mechanisms promoting tolerance to aggressive Phytophthora species in hybrid poplar

The threat of a major tree pathogen to forest soil mesofauna food webs and ecosystem functioning

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