Inheritance of resistance to Meloidogyne incognita race 3 in cotton accession TX 25

Herança da resistência do acesso TX 25 de algodoeiro a Meloidogyne incognita raça 3

ABSTRACT.

Cotton producers worldwide suffer with the losses caused by the presence of phytonematodes. The aim of the present study was to investigate the inheritance of resistance to Meloidogyne incognita race 3 in Gossypium hirsutum variety punctatum accession TX 25. Accessions of Gossypium sp. were obtained from the germplasm bank of Embrapa Cotton. Two experiments were performed in two consecutive years. In the first experiment, a susceptible parental line, FiberMax 966, a resistant parental line, TX 25, and their F₁, F₂ and backcross generations were tested. In the second experiment, parental lines FiberMax 966 and TX 25, their F₂ generation, and genotypes M315 (resistant), LA887 and DeltaOpal (moderately resistant) were tested. In both experiments, plants were inoculated with 2000 eggs and J2 of M. incognita race 3. The gall index, egg mass index and reproduction factor were evaluated 120 days following inoculation. In the first experiment, plants from the F₁ and backcross generations were susceptible. Plants from the F₂ generation presented a 3:1 resistant-to-susceptible ratio in the two experiments, indicating oligogenic resistance.

Keywords:
Gossypium hirsutum; gall nematode; gene segregation