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<p>Sesame (<i>Sesamum indicum</i> L.) is a rapidly expanding oilseed crop in Brazil. This study aimed to identify the causal agent of charcoal rot in sesame-producing areas of Goiás and Mato Grosso and to characterize the pathogen isolates morphologically, molecularly, and genetically. Symptomatic stems were collected in three municipalities, and sixty-one fungal isolates were identified as <i>Macrophomina phaseolina</i> based on cultural and microscopic traits, PCR with species-specific primers, and partial ITS sequencing. Pathogenicity tests reproduced field symptoms and confirmed the pathogen through re-isolation, fulfilling Koch’s postulates. Genetic diversity analysis using seven ISSR markers revealed a high proportion of polymorphic loci (97.2%) and considerable variability among isolates, with clustering patterns mainly associated with geographic origin. In greenhouse assays, cultivar BRS Anahí showed lower disease severity (51.16% disease index), while Trebol exhibited the highest severity (68.06% disease index), and K3 showed intermediate values (58.56% disease index), with significant differences among cultivars (<i>p</i> = 0.0363). This study reports the first confirmed occurrence of charcoal rot caused by <i>M. phaseolina</i> in Central-West Brazil and reveals genetic diversity among isolates, as well as differences in disease severity among sesame cultivars.</p>

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Genetic variability of Macrophomina phaseolina associated with charcoal rot of sesame in expanding agricultural areas of Central-West Brazil

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年6月29日

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  • Júlia Moraes Gomes,
  • Emilly Ferreira Braga Rios,
  • Moisés Rodrigues Silva,
  • Eder Marques,
  • Marcos Gomes da Cunha

摘要

Sesame (Sesamum indicum L.) is a rapidly expanding oilseed crop in Brazil. This study aimed to identify the causal agent of charcoal rot in sesame-producing areas of Goiás and Mato Grosso and to characterize the pathogen isolates morphologically, molecularly, and genetically. Symptomatic stems were collected in three municipalities, and sixty-one fungal isolates were identified as Macrophomina phaseolina based on cultural and microscopic traits, PCR with species-specific primers, and partial ITS sequencing. Pathogenicity tests reproduced field symptoms and confirmed the pathogen through re-isolation, fulfilling Koch’s postulates. Genetic diversity analysis using seven ISSR markers revealed a high proportion of polymorphic loci (97.2%) and considerable variability among isolates, with clustering patterns mainly associated with geographic origin. In greenhouse assays, cultivar BRS Anahí showed lower disease severity (51.16% disease index), while Trebol exhibited the highest severity (68.06% disease index), and K3 showed intermediate values (58.56% disease index), with significant differences among cultivars (p = 0.0363). This study reports the first confirmed occurrence of charcoal rot caused by M. phaseolina in Central-West Brazil and reveals genetic diversity among isolates, as well as differences in disease severity among sesame cultivars.