Etiology of Chickpea Yellowing Syndrome (CYS) in Argentina: The Role of Fungal and Viral Pathogens

Chickpea Yellowing Syndrome (CYS) is a major disease complex affecting chickpea ( Cicer arietinum L.) in Argentina, yet its etiology remains poorly understood. This study aimed to identify primary fungal and viral agents associated with CYS. A comprehensive survey (2020–2022) collected symptomatic and asymptomatic plants from 22 fields in the provinces of Córdoba, Santiago del Estero, Catamarca, and Salta. Fungal agents were identified by morphological and molecular methods. Pathogenicity of 55 Fusarium spp. isolates was evaluated on susceptible cultivar 'Kiara', while aggressiveness of pathogenic isolates was characterized by the Area Under the Disease Progress Curve calculated from disease incidence. Viral presence was screened using ELISA and RT-PCR. Fusarium was the dominant fungal genus (74%), with F. oxysporum being the most prevalent species. Pathogenicity tests confirmed 82% of isolates as pathogenic. Notably, pathogenic isolates were also recovered from asymptomatic plants. Aggressiveness analysis classified isolates into distinct clusters, identifying a highly aggressive F. proliferatum isolate. Crucially, this work provides the first report of bean leafroll virus (BLRV; Luteovirus phaseoli ) and alfalfa mosaic virus (AMV; Alfamovirus AMV ) infecting chickpea in Argentina. BLRV was detected in 36% of fields and AMV in 9%. These findings demonstrate that CYS etiology is complex, resulting from the interaction of Fusarium species and viruses, providing the essential knowledge required to design effective integrated management strategies.