First Report and Molecular Characterization of Sclerotinia sclerotiorum Causing Stem Rot on Artichoke

Abstract

Stem rot symptoms observed on artichoke (Cynara scolymus L.) were investigated to identify the causal pathogen and confirm its identity through integrated morphological and molecular approaches. Field surveys in commercial artichoke fields revealed progressive wilting, water-soaked lesions on stems, and white cottony mycelial growth accompanied by sclerotia formation under humid conditions. Fungal isolates obtained from infected stem tissues produced fast-growing, white, aerial mycelium on potato dextrose agar, with black, irregular sclerotia developing after incubation. Morphological characteristics were consistent with Sclerotinia sclerotiorum. Pathogenicity tests conducted under controlled greenhouse conditions successfully reproduced stem rot symptoms on healthy artichoke plants, fulfilling Koch’s postulates. Molecular identification using ITS rDNA sequencing confirmed the isolates as S. sclerotiorum, showing high sequence similarity with reference isolates in global databases. Phylogenetic analysis placed all isolates within a well-supported clade corresponding to S. sclerotiorum, indicating low intraspecific variability among sampled populations. This study represents the first confirmed report of S. sclerotiorum causing stem rot on artichoke in the surveyed region, expanding the known host range of this pathogen. Disease development was favored by cool temperatures and prolonged moisture periods, conditions commonly associated with dense canopy microclimates in artichoke cultivation. The findings highlight the epidemiological risk posed by S. sclerotiorum in high-value vegetable and specialty crop systems and emphasize the importance of early detection and integrated disease management strategies.