Morphological and Molecular Characterization of Diplodia seriata Causing Cane Blight on Grapevine in Semi-Arid Regions

Abstract

Diplodia seriata is an important fungal pathogen associated with grapevine trunk diseases, causing cane blight and significant yield decline in vineyards, particularly under semi-arid climatic conditions. The present study was conducted to investigate the morphological and molecular characterization of D. seriata isolates obtained from symptomatic canes of Grapevine showing dieback, cane necrosis, vascular discoloration, and reduced bud viability. Diseased samples were collected from commercial vineyards located in semi-arid regions, and the pathogen was isolated using standard tissue plating techniques on potato dextrose agar (PDA). Morphological characterization was carried out based on colony appearance, pigmentation, growth rate, and conidial features, including size, shape, and septation. Molecular identification was performed through PCR amplification and sequencing of ITS rDNA regions, followed by phylogenetic analysis to determine genetic relationships with global isolates. Sequence comparison confirmed the identity of the pathogen as D. seriata, showing high similarity with reference sequences in public databases. Phylogenetic reconstruction grouped the isolates within a well-supported clade of Diplodia species associated with grapevine trunk diseases, indicating limited but notable genetic variation among regional populations. Pathogenicity tests conducted on healthy grapevine cuttings reproduced typical cane blight symptoms, thereby confirming the virulence of the isolates and fulfilling Koch’s postulates. The study highlights the integration of morphological and molecular tools for accurate identification of D. seriata and provides baseline information on its occurrence in semi-arid viticultural systems. These findings are essential for improving disease diagnosis, vineyard sanitation practices, and the development of effective management strategies to reduce cane blight incidence and maintain grapevine productivity.