Resistance to Meloidogyne arenaria in Arachis spp. Germplasm.

Field and greenhouse evaluations of 116 wild Arachis spp. genotypes demonstrated the presence of resistance to reproduction of the root-knot nematode Meloidogyne arenaria race 1. Resistance in greenhouse tests was based on test lines having </= 2.5% of the number of eggs per gram of roots as did the susceptible A. hypogaea cv. Tamnut 74. In field tests, resistant genotypes were identified on the basis of having lower (P = 0.05) final nematode population densities than did Tamnut 74. Resistance was identified in genotypes from 11 of 15 wild species tested and in 10 of 20 genotypes belonging to undescribed species. Results of field and greenhouse experiments were similar; 26 of 31 genotypes common to both tests gave similar responses in both tests. Resistance to M. arenaria was identified in the complex hybrid TP-135, which was derived from A. hypogaea cv. Florunner x (A. batizocoi K 9484 x [A. cardenasii GKP 10017 x A. chacoensis GKP 10602])x. In a single greenhouse test, three of six genotypes resistant to M. arenaria were also resistant to M. hapla. These data indicate that the Arachis spp. germplasm contains several sources of resistance to M. arenaria and possibly M. hapla. Some of this resistance is in germplasm that is genetically compatible with A. hypogaea. The complex hybrid TP-135 incorporates resistance from wild species into the genetic background of A. hypogaea. On the basis of these data, we believe it may be possible to develop peanut cultivars with high levels of resistance to M. arenaria and M. hapla.