Emergence of potato virus Y outbreaks in tomatoes in Brazil, the disease and spread

Abstract

The emergence of 'Mexican Fire' disease in Brazilian tomato fields, attributed to potato virus Y (PVY), has raised concerns. Characterized by severe necrosis on median leaves, the definitive etiological agent of this disease remained unverified despite PVY detection in symptomatic plants. Our study aimed to elucidate the causal agent, occurrence, spread, and symptomatology of Mexican Fire. Deep sequencing of tomato leaves with typical necrotic symptoms confirmed the association with PVY, reinforcing its role as the causal agent. Serological tests with a PVY-specific polyclonal antibody consistently correlated symptoms with virus presence in a fresh market tomato field, with higher PVY incidence near older tomato and maize plants. Necrotic leaf distribution analysis revealed a predominant occurrence in median leaves, progressing upwards. Deep sequencing of symptomatic field samples exclusively detected PVY, reaffirming its role in symptom induction. Importantly, PVY inoculation under field and greenhouse conditions fulfilled Koch's Postulates, triggering leaf necrosis. Our findings unequivocally establish PVY as the causal agent of Mexican Fire disease, shedding light on its etiology, incidence, spread, and symptom expression, crucial for effective disease management strategies.