Resistance to root-lesion nematodes on Coffea canephora

Root-lesion nematodes (Pratylenchus spp.) are widely distributed in coffee plantations worldwide. In Central America, many of them are highly pathogenic on Coffea arabica causing important economic damage. The poor efficiency of nematicide treatments to control Pratylenchus spp. was demonstrated in Guatemala. In this country, C. canephora was used as a rootstock for 30 years empirically. Analysis pointed out the low level of root-lesion nematodes in the fields where this grafting technique was used. Comparative studies of penetration dynamics and reproductive fitness on coffee seedlings as well as field trials demonstrated the existence of pre- and post-infection factors of partial resistance to Pratylenchus spp. in some C. canephora genotypes. Complementary histological studies of roots showed no noticeable structural differences between C. arabica and C. canephora. On the other hand, the presence of large amounts of polyphenols was observed in the roots of a C. canephora resistant genotype even before nematode penetration, suggesting the existence of constitutive factors of resistance. Sources and mechanisms of resistance must be investigated more exhaustively among C. canephora germplasm. Grafting onto C. canephora constitutes today the best alternative to nematicide treatments for controlling phytoparasitic nematode communities in the C. arabica coffee crop, as some C. canephora genotypes also show resistance to highly pathogenic root-knot nematodes (Meloidogyne spp.). (Résumé d'auteur