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Histopathological study reveals new insights into responses of chestnut (Castanea spp.) to root infection by Phytophthora cinnamomi
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Orientador(es)
Resumo(s)
The European chestnut (Castanea sativa) is threatened by the hemibiotrophic
oomycete Phytophthora cinnamomi, the causal agent of ink
disease. Chestnut species have different susceptibility levels to P. cinnamomi,
with the Asian species (C. crenata; C. mollissima) exhibiting the highest level
of resistance. A histological approach was used to study the responses
exhibited by susceptible and resistant chestnut genotypes by characterizing
the early stages of P. cinnamomi infection and the cellular responses it
induces in roots. C. sativa (susceptible) and C. crenata (resistant) plantlets
were inoculated with a P. cinnamomi virulent isolate with a zoospore
suspension or by direct contact with mycelia agar pieces. Root samples were
collected at 0.5, 3.5, 24, 48, and 72 h after inoculation (hai) for microscopic
observations. Penetration was observed in both species at 0.5 and 3.5 hai with
mycelium and zoospore inoculations, respectively. In both inoculation methods, following penetration into the rhizodermis, P. cinnamomi hyphae
grew inter- and intracellularly through the cortex and into the vascular
cylinder. C. crenata cells displayed a delay in the pattern of infection by
having fewer cell layers colonized compared with C. sativa. At 72 hai, the
collapse of the first layers of C. sativa cortical cells was observed, indicating
the beginning of necrotrophy. C. crenata was able to respond more efficiently
to P. cinnamomi than C. sativa by restricting the pathogen’s growth area
through the early activation of resistance responses such as callose deposition
around some intracellular hyphae, hypersensitive response-like cell death, cell
wall thickening, and accumulation of phenolic-like compounds
Descrição
Palavras-chave
disease control genetics ink disease microscopy pest management resistance root rot susceptibility
Contexto Educativo
Citação
Fernandes P, Machado MH, Silva MC, Costa RL (2021). Histopathological study reveals new insights into responses of chestnut (Castanea spp.) to root infection by Phytophthora cinnamomi. Phytopathology 111(2):345-355
Editora
The American Phytopathological Society