Morphological traits and SSR-Based genetic diversity of Macrophomina isolates causing charcoal rot in sugar beet in Serbia

Abstract

Macrophomina spp. are soil-borne phytopathogenic fungi within the division Ascomycota, known to cause significant yield losses in a wide range of crops, including sugar beet. In recent decades, root rot outbreaks associated with Macrophomina have increased in the Republic of Serbia, likely influenced by climate change and environmental stress. Despite this, there is limited information on the morphological and molecular characteristics of Macrophomina isolates from sugar beet. This study aimed to investigate the morphological and physiological variability of Macrophomina isolates, characterize them at the molecular level, and evaluate their genetic diversity using Simple Sequence Repeats (SSR) markers. The isolates of Macrophomina exhibit considerable phenotypic variation in colony morphology and chlorine sensitivity, suggesting inherent genetic diversity and potential differences in adaptation or survival under varying environmental conditions. Optimal growth occurred at 30–35 °C, with pH tolerance between 4.0 and 7.0. Genetic diversity assessed using SSR markers revealed a relatively low level of variation among isolates. Principal Coordinates Analysis (PCoA) indicated that a few isolates formed distinct genetic clusters, indicating a limited population structure. These findings are essential for the development of resistant sugar beet cultivars and informed disease management practices in regions increasingly affected by Macrophomina outbreaks.