Effects of <i>Meloidogyne incognita</i> on agronomic parameters and structural changes in eggplant ( <i>Solanum gilo</i> Raddi) roots treated with <i>Purpureocillium lilacinum</i>

Meloidogyne spp. induce structural changes during the development of root-knot galls, leading to reduced productivity in various crop species, including eggplants (Solanum gilo). In this study, we evaluated the impact of Meloidogyne incognita on the development and structure of root-knot galls in eggplants and assessed the effect of the fungus Purpureocillium lilacinum as nematicide. Three treatments were applied: plants inoculated with M. incognita, plants inoculated with M. incognita + P. lilacinum, and a control. Agronomic impact was assessed 72 days after inoculation (DAI). Histological, morphological, and immunocytochemical analyses were performed at multiple time points after the start of the experiment. There was a reduction in weight as well as in root and shoot growth in the plants inoculated with M. incognita, whereas the plants from the other two treatments presented similar values. Galls and giant cells were observed at 18 DAI. Purpureocillium lilacinum did not interfere with giant cell formation but reduced the number of galls, nematodes, and eggs in the roots. The detection of methyl-esterified homogalacturonans indicated flexible cell walls in young galls, with increased rigidity due to low methyl esterification in mature galls. The growth of the aerial part and mass gain of the eggplants were negatively impacted by M. incognita; however, the use of the P. lilacinum strains reduced crop damage, indicating its efficiency as a biological control agent.