Tetranychus ludeni (Acari: Tetranychidae) infestation triggers a spatiotemporal redox response dependent on soybean genotypes.

The redox homeostasis and photosynthetic pigments changes vary with Tetranychus ludeni infestation, with longer-cycle genotypes showing greater tolerance and efficiency in antioxidant defense. Infestations of Tetranychus ludeni Zacher (Tetranychidae) have been frequently observed in soybean plants. In this context, understanding the oscillation of redox homeostasis is crucial for detecting and assessing the stress levels caused in the plants by these organisms. The impacts of these infestations on redox metabolism and photosynthetic pigments are currently unknown. Therefore, we examined the hypothesis that T. ludeni infestations in soybean plants can influence redox homeostasis and photosynthetic pigments in a spatiotemporal manner, varying between different infestation times, modules and genotypes. For this purpose, soybean plants of the genotypes Monsoy, maturity group 5.7, and Brasmax, maturity group 6.3, grown in a controlled environment, were exposed to infestation and evaluated at two periods: 14 and 24 days. A variation in the distribution of T. ludeni within the infested plants over time increased the activity of ascorbate peroxidase and catalase, especially in Monsoy, reducing the content of hydrogen peroxide and superoxide, which prevented lipid peroxidation in the apical region in both genotypes. In the basal region, low chlorophyll indices corroborated by the yellow coloration of trifoliate leaves, high levels of membrane stability loss, and accumulation of hydrogen peroxide and superoxide characterized senescent trifoliate leaves in Brasmax, 24 days post infestation. Thus, the infestation of T. ludeni has a complex and significant impact on the redox metabolism of soybean plants, especially in shorter-cycle genotypes such as Brasmax. Furthermore, the oscillation of homeostasis can be considered as a good biochemical marker for selecting more suitable genotypes that are less sensitive and prone to infestations.