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An innovative integrated approach to characterize coffee resistance mechanisms to Colletotrichum kahawae
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Resumo(s)
Coffee berry disease, caused by the hemibiotrophic fungus Colletotrichum kahawae, is a major
constraint to Arabica coffee production in Africa. Coffee variety Catimor 88, which exhibit
field resistance in Kenya, was selected to characterize the resistance to C. kahawae,
comparatively to the susceptible variety Caturra. Hypocotyls of both varieties were challenged
with C. kahawae (isolate Que2 from Kenya) and samples were collected during infection timecourse,
simultaneously for analysis of fungal growth and plant responses (light microscopy),
evaluation of enzymatic activities (spectrophotometry, electrophoresis, histochemistry) and
gene expression analysis (quantitative real-time PCR).
The resistance was characterized by restricted fungal growth associated with the hypersensitive
reaction and early accumulation of phenolic-like compounds in the cell walls and cytoplasmic
contents. Similar responses were detected in the susceptible variety but in a significantly lower
percentage of infection sites. Regarding the genes related to the salicylic acid, jasmonic acid
(JA) and ethylene (ET) pathways (phytohormones biosynthesis, reception, and responsiverelated
genes), this study suggests the involvement of JA in the resistance while ET seems to
be more related with the susceptibility.
The expression of genes related to recognition and signaling (RLK, LRR-K, CML, PTL) and
cell wall modification genes (PME41, MUR4) was induced in both coffee varieties, at early
stages of the infection. However, in the resistant variety, a higher expression of recognition
and signaling genes was induced together with the PME41 gene during fungal penetration, and
the induction of expression of the Lignin-forming anionic peroxidase-like gene (PER4) was
supported by the increase of total peroxidase activity and of an anionic isoform. Peroxidase
was localized in the walls and cytoplasmic contents of host cells, at the infection sites. The new
data obtained enable to identify potential biomarkers of disease resistance that, once validated,
will be useful for marker-assisted selection in coffee breeding programmes
Descrição
Doutoramento em Engenharia Agronómica - Instituto Superior de Agronomia - UL
Palavras-chave
coffee berry disease (CBD) Coffea sp. cytology biochemistry gene expression
Contexto Educativo
Citação
Diniz, I.I.P.S. - An innovative integrated approach to characterize coffee resistance mechanisms to Colletotrichum kahawae. Lisboa: ISA, 2018, 104 p.