Ferroptose na interação incompatível entre o feijão-caupi (Vigna unguiculata [L.] Walp) e o vírus do mosaico severo do caupi (CPSMV)

Abstract

Cowpea (Vigna unguiculata [L.] Walp.) is a legume of great socioeconomic importance in Brazil, especially in the North, Northeast, and Central-West regions, due to its adaptation to adverse conditions. However, the crop is affected by pests and diseases, especially viral infections such as Cowpea severe mosaic virus (CPSMV), which causes significant yield losses. Plants rely on several defense mechanisms against pathogens, including programmed cell death (PCD), which plays a crucial role in limiting the spread of biotrophic organisms. Programmed cell death (PCD) includes subtypes defined by molecular and morphological features, such as ferroptosis – recently described in plants and associated with responses to both abiotic and biotic stresses. This PCD subtype is characterized by the accumulation of reactive oxygen species (ROS), lipid peroxidation, and intracellular iron dependence. Thus, this study investigated the possible occurrence of ferroptosis in the incompatible interaction between cowpea cv. ‘Marataoã’ (resistant) and CPSMV, using the ferroptosis inhibitor ferrostatin-1 (Fer-1). Given the relevance of the cowpea x CPSMV pathosystem, this study aimed to explore the potential occurrence of ferroptosis in the incompatible interaction between cowpea cultivar ‘Marataoã’ (resistant) and CPSMV, using the specific ferroptosis inhibitor ferrostatin-1 (Fer-1). To this end, cowpea leaves were inoculated with CPSMV and treated with Fer-1 twelve hours post-inoculation, with samples collected two days after inoculation. We assessed Fe3+ accumulation, hydrogen peroxide (H2O2) and malondialdehyde (MDA) levels, as well as the activity of antioxidant enzymes including ascorbate peroxidase (APX), catalase (CAT), and superoxide dismutase (SOD). Cowpea plants cv. ‘Marataoã’ inoculated with CPSMV exhibited changes in several biochemical parameters following Fer-1 treatment. Systemic leaflets collected two days post-inoculation showed greater Fe3+ accumulation, elevated lipid peroxidation, and reduced catalase activity compared to untreated inoculated plants. Treatment with Fer-1 was able to restore these parameters to levels comparable to those of uninoculated controls, suggesting a potential involvement of the ferroptosis pathway in the systemic response to CPSMV. However, Fer-1 treatment did not significantly alter H2O2 levels, and its effects on APX and SOD activity were inconsistent and inconclusive. Therefore, further experiments with optimized protocols are needed to confirm the role of ferroptosis in cowpea’s defense response to CPSMV.