Morphological Description and Molecular Phylogeny of Macrophomina phaseolina Isolates from Different Host Plants

Abstract

Morphological description and molecular phylogeny of Macrophomina phaseolina isolates from different host plants were investigated to assess intraspecific variability and host-associated differentiation. Diseased plant samples exhibiting typical charcoal rot symptoms, including stem discoloration, root decay, and premature wilting, were collected from diverse crop hosts. Fungal isolates were obtained through standard tissue isolation techniques and characterized based on colony morphology, growth rate, sclerotial size, shape, and pigmentation on culture media. Molecular identification was performed using PCR amplification and sequencing of ITS rDNA regions, followed by phylogenetic analysis to determine genetic relationships among isolates. Results revealed notable morphological variability among isolates, although all were confirmed as M. phaseolina. Phylogenetic analysis showed clustering of isolates into distinct groups, with partial association to host origin, suggesting limited but detectable host-linked genetic differentiation. High genetic similarity among most isolates indicated a broadly conserved genome structure within the species across different crops. Variations in sclerotial production and growth dynamics reflected phenotypic plasticity influenced by host and environmental conditions. The integration of morphological and molecular data provided robust resolution for accurate identification and understanding of population structure. These findings highlight the adaptability of M. phaseolina across multiple host plants and emphasize its significance as a polyphagous pathogen. The study supports the need for continuous monitoring and integrated management strategies to mitigate charcoal rot disease in diverse agricultural systems.