New data on the specificity of the root-knot nematode resistance genes Me1 and Me3 in pepper

Root-knot nematodes, Meloidogyne spp.. cause severe damage on solanaceous crops, including tomato and pepper. The objective of this study was to test whether nematodes virulent against the tomato Mi resistance gene were able to overcome the Me1 and Me3 resistance genes from pepper. For that purpose, a collection of 22 Meloidogyne arenaria, Meloidogyne incognita and Meloidogyne javanica isolates, avirulent or virulent against the Mi gene, was assembled. The reproduction of each isolate was evaluated on both susceptible and resistant tomato and pepper genotypes in a growth chamber. The Me1 resistance gene controlled all the avirulent and Mi-virulent nematodes tested, and therefore appears promising for pepper breeding. In contrast, one M. arenaria and two H. incognita virulent isolates were shown to overcome the pepper Me3 resistance gene. These results encourage the testing of a large number of Meloidogyne isolates to evaluate the plant-nematode interaction, which could have important consequences for the use and management of resistance genes in the field with respect to specificity and durability of the resistance.