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<p>Stem rot disease in groundnut, caused primarily by the fungus <i>Sclerotium rolfsii</i>, leads to wilting, stem decay, and significant yield loss, especially under warm and moist soil conditions. In Indian conditions, stem rot can cause yield losses ranging from 10 to 30%. The present research gaps include limited availability of resistant varieties, inadequate understanding of pathogen variability, underutilization of biological control agents, insufficient disease forecasting tools, and the impact of climate change. The study investigated the morphological and pathogenic variability among <i>Agroathelia rolfsii</i> (syn. <i>Sclerotium rolfsii</i>) isolates responsible for groundnut stem rot disease (GSr) across major groundnut growing areas of Karnataka, India. In total 30 isolates displayed considerable variability in sclerotial traits such as size, color, shape, and production per unit area, with BagSr-17 showing the highest sclerotial density (9.89/cm<sup>2</sup>). Pathogenicity assays on five groundnut cultivars (Dh-257, Dh-256, GPBD-5, KDG-128, and TAG-24) indicated a wide range of virulence. Isolates DhaSr-1 and AndSr-29 were the most aggressive, causing 100% disease incidence with the shortest incubation periods. Pathogenic variability on different cultivars revealed, Dh-256 and Dh-257 as relatively more tolerant across multiple isolates. Based on pathogenic responses, isolates were classified into five distinct pathotypes, aiding in understanding host–pathogen interactions and guiding resistance breeding. DhaSr-1 exhibited the highest oxalic acid production (2.30&#xa0;mg/ml), aligning with its pathogenic potency. Internal transcribed spacer (ITS) 1 and 4 region sequencing confirmed isolate identity, and phylogenetic analysis revealed significant genetic variability among the study isolates compared to global counterparts, suggesting region-specific evolution. The study offers valuable insights into <i>A. rolfsii</i> diversity, emphasizing the importance of region-specific disease management and targeted breeding for stem rot resistance in groundnuts.</p>

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Deciphering the morphological and pathogenic variability among Sclerotium rolfsii: A causal agent of Groundnut stem rot disease

  • 期刊论文

  • 发表日期：

    2025年8月11日

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  • Shivalingappa H,
  • Ashtaputre S A,
  • Jahagirdar S,
  • Rao MSL,
  • Motagi BN,
  • Jones P,
  • Mahesha HS,
  • Raghunandhan A,
  • Shivakumara KT

摘要

Stem rot disease in groundnut, caused primarily by the fungus Sclerotium rolfsii, leads to wilting, stem decay, and significant yield loss, especially under warm and moist soil conditions. In Indian conditions, stem rot can cause yield losses ranging from 10 to 30%. The present research gaps include limited availability of resistant varieties, inadequate understanding of pathogen variability, underutilization of biological control agents, insufficient disease forecasting tools, and the impact of climate change. The study investigated the morphological and pathogenic variability among Agroathelia rolfsii (syn. Sclerotium rolfsii) isolates responsible for groundnut stem rot disease (GSr) across major groundnut growing areas of Karnataka, India. In total 30 isolates displayed considerable variability in sclerotial traits such as size, color, shape, and production per unit area, with BagSr-17 showing the highest sclerotial density (9.89/cm2). Pathogenicity assays on five groundnut cultivars (Dh-257, Dh-256, GPBD-5, KDG-128, and TAG-24) indicated a wide range of virulence. Isolates DhaSr-1 and AndSr-29 were the most aggressive, causing 100% disease incidence with the shortest incubation periods. Pathogenic variability on different cultivars revealed, Dh-256 and Dh-257 as relatively more tolerant across multiple isolates. Based on pathogenic responses, isolates were classified into five distinct pathotypes, aiding in understanding host–pathogen interactions and guiding resistance breeding. DhaSr-1 exhibited the highest oxalic acid production (2.30 mg/ml), aligning with its pathogenic potency. Internal transcribed spacer (ITS) 1 and 4 region sequencing confirmed isolate identity, and phylogenetic analysis revealed significant genetic variability among the study isolates compared to global counterparts, suggesting region-specific evolution. The study offers valuable insights into A. rolfsii diversity, emphasizing the importance of region-specific disease management and targeted breeding for stem rot resistance in groundnuts.