Morphological and Molecular Characterization of Cladosporium Species Associated with Leaf Mold of Tomato in Greenhouses

Abstract

Morphological and molecular characterization of Cladosporium species associated with leaf mold of tomato in greenhouses was undertaken to identify causal agents, assess species diversity, and confirm their phylogenetic relationships. Surveys were conducted in greenhouse tomato production systems exhibiting typical symptoms such as pale yellow leaf spots, chlorosis on upper leaf surfaces, olive-green velvety growth on the abaxial surface, and progressive leaf senescence. Diseased leaf samples were collected and fungal isolates were obtained using standard isolation techniques on selective media. Morphological identification was based on colony characteristics, conidial shape, septation, and conidiophore structure. Results revealed the presence of multiple Cladosporium species associated with tomato leaf mold, indicating species complexity within greenhouse environments. Considerable variation was observed among isolates in colony growth rate, pigmentation, and sporulation patterns. Molecular characterization using ITS rDNA sequencing confirmed species identity and revealed genetic divergence among isolates. Phylogenetic analysis grouped the isolates into distinct clades corresponding to known Cladosporium taxa, supporting morphological differentiation and indicating possible host-adapted lineages. Disease severity was found to be strongly influenced by high humidity and poor air circulation typical of greenhouse conditions, which favored sporulation and rapid disease spread. The study emphasizes the importance of integrating morphological and molecular approaches for accurate identification of Cladosporium species in tomato production systems. These findings provide a basis for improved disease monitoring and greenhouse management strategies aimed at reducing leaf mold incidence and enhancing crop health.