ABSTRACT
Macrophomina phaseolina and Meloidogyne javanica: Interaction of the pathosystem in soybean

Lorrayne Zampar Alves1*, Monique Thiara Rodrigues e Silva1, Eduarda Thais Sonda1, Giovanni Vonsowski Guarido1, Abner Resena Carvalho2, João Manuel Hernandes Dorce Domingues2, Kátia Regina Schwan-Estrada1, and Claudia Regina Dias-Arieira1
 
Interactions between soil pathogens, such as those involving fungi and nematodes, can lead to disease complexes that are difficult to manage, intensifying crop losses. Macrophomina phaseolina, for instance, has become a recurring problem in soybean (Glycine max (L.) Merr.) fields under drought conditions, particularly in nematode-infested areas. This study aimed to investigate the M. phaseolina-Meloidogyne javanica pathosystem in soybean to understand how these microorganisms interact with each other and with the plant’s defense mechanisms. Three experiments were conducted: (i) A nematode reproduction and disease severity assessment, (ii) a split-root experiment, and (iii) an analysis of plant defense-related enzymes. Soybean plants were subjected to four treatments: Control, inoculation with M. javanica, inoculation with M. phaseolina, and co-inoculation. The results revealed an antagonistic interaction between pathogens, as co-inoculation reduced M. javanica reproduction by up to 68.6% and decreased the severity of injuries caused by M. phaseolina. Similar results were observed in the two trials of the split-root experiment, with co-inoculation producing greater reductions in soybean growth than single inoculation. Enzymatic analysis showed an increase in polyphenol oxidase activity at 7 d after inoculation in single-inoculation treatments but not in the co-inoculated group. Peroxidase and glucanase activities increased over time, without differing significantly between treatments. This study contributes to our understanding of pathogen interactions in soybean and demonstrates that, even when pathogens negatively influence each other, their combined presence can exacerbate crop damage.
Keywords: Charcoal rot of soybean, defense mechanisms, root-knot nematode, soilborne fungi.
1Universidade Estadual de Maringá, Pós Graduação em Agronomia, Maringá, Paraná, 87020-900, Brasil.
2Universidade Estadual de Maringá, Graduação em Agronomia, Maringá, Paraná, 87020-900, Brasil.
*Corresponding author (lorrayne_alves_@hotmail.com).