Residual-resistance effect of two known QTLs in cotton genotypes on Meloidogyne enterolobii reproduction

What is it about?

A new race of Meloidogyne enterolobii,the guava root-knot nematode (RKN), recently reported in Brazil and in the USA, can cause damage to cotton crop. Genetic resistance is a promising approach to _x000D_ manage this RKN. In this study, 18 accessions including Gossypium hirsutum G. barbadense, interspecific hybrids, and G. arboreum were examined for their susceptibility or resistance to M. enterolobii. The inoculations were made with 10,000 M. enterolobii eggs and, after a period similar to field conditions (120 days), several variables were evaluated and the reproduction factor (RF) was the best. The susceptible control, 'FM 966', displayed high reproduction factor (RF: 86.88 - 102.20) in both experiments, indicating the aggressiveness of the M. enterolobii cotton population (race 2). All G. barbadense genotypes were classified as susceptible and G. arboreum genotype also in both experiments. Despite the virulence of M. enterolobii race 2, some G. hirsutum cotton genotypes used in our experiments with RKN resistance QTLs (quantitative trait loci, qMi-C11 and qMi-C14), demonstrated a significant partial resistance (about 80%) in reducing the final high nematode population after 120 days of inoculation. Our study highlights the importance of selecting residual resistance effect on cotton to Meloidogyne spp. after more nematode cycles to show the final nematode population reduction to mitigate the impact of M. enterolobii to cotton crop.

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