Early responses of coffee immunity-related genes to root-knot nematode infection

The root-knot nematode (RKN) Meloidogyne incognita is one of the most damaging parasites of coffee (Coffea arabica) plantations. The aim of this study was to compare defense-related genes transcription patterns in resistant and susceptible coffee genotypes after nematode challenge. Root tips of the C. arabica 'UFV' (resistant) and 'CV' (susceptible) genotypes were collected at 4, 5 and 6 days post-infection (DPI) with M. incognita. The expression patterns of 88 genes related to plant immunity were assessed by qRT-PCR in infected and control coffee roots. In susceptible plants, most of the genes were suppressed from 5 DPI, when nematode feeding sites are induced. In resistant plants, gene expression was mostly activated at 6 DPI, when a hypersensitive response-like phenotype is detectable. Resistance was associated with over-expression of genes coding for Miraculin (defense), RGLG1 (protein degradation), SENA (senescence-associated cell death), NLR (immunity signaling), CaWRK11 (transcription factor), and OBP (cell wall modification). Interestingly, some genes presented contrasting profiles during the compatible (S) and incompatible (R) interactions: C4H, NLR, TUBBY (transcription factor), and CAFsy (alkaloid metabolism-related). A NRP (N-rich protein)-based response could to be associated with the coffee response to the nematode. Data obtained here improve our knowledge about the coffee immune responses to M. incognita and provide novel genes for plant resistance breeding.