Histopathology of <i>Thecaphora frezzii</i> Colonization: A Detailed Analysis of Its Journey Through Peanut (<i>Arachis hypogaea</i> L.) Tissues
Over the past few decades, peanut smut, caused by <i>Thecaphora frezzii</i>, has evolved from an emerging disease to a major global threat to peanut production. However, critical knowledge gaps persist regarding the anatomical pathways and host responses involved in infection, colonizati...
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2025-04-01
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| author | María Florencia Romero Sergio Sebastián Samoluk José Guillermo Seijo Ana María Gonzalez |
| author_facet | María Florencia Romero Sergio Sebastián Samoluk José Guillermo Seijo Ana María Gonzalez |
| author_sort | María Florencia Romero |
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| description | Over the past few decades, peanut smut, caused by <i>Thecaphora frezzii</i>, has evolved from an emerging disease to a major global threat to peanut production. However, critical knowledge gaps persist regarding the anatomical pathways and host responses involved in infection, colonization, and sporulation. This study examines the pathosystem and histopathology of the biotrophic phase of <i>T. frezzii</i> in the susceptible cv. Granoleico. Anatomical analyses were conducted using light microscopy, confocal laser scanning, and scanning electron microscopy. Our findings reveal that <i>T. frezzii</i> enters the host through the peg rather than the ovary tip, invading during the R2-subterranean phase. Fruit colonization occurs at the R3-stage when the mechanical layer between the mesocarp and endocarp has not yet formed. Hyphal entry into the seed takes place between the R3-medium and R3-late pod stages via the funiculus, leading to extensive seed coat colonization without penetrating the embryo. Once inside, hyperplasia and hypertrophy are triggered, coinciding with teliospore formation. Teliosporogenesis disrupts nutrient translocation, arresting embryo development. The hyphae colonize tissues intracellularly, utilizing living cells of the vascular bundles and following the peanut’s photoassimilate transport pathway. Investigating these structural responses in phenotypically contrasting peanut genotypes may provide key insights into the anatomical barriers and defense mechanisms that determine disease susceptibility and resistance, ultimately contributing to the development of resistant cultivars. |
| format | Article |
| id | doaj-art-20d23647e9f243e893f3c7457f338752 |
| institution | DOAJ |
| issn | 2223-7747 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | MDPI AG |
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| spelling | doaj-art-20d23647e9f243e893f3c7457f3387522025-08-20T03:03:25ZengMDPI AGPlants2223-77472025-04-01147108310.3390/plants14071083Histopathology of <i>Thecaphora frezzii</i> Colonization: A Detailed Analysis of Its Journey Through Peanut (<i>Arachis hypogaea</i> L.) TissuesMaría Florencia Romero0Sergio Sebastián Samoluk1José Guillermo Seijo2Ana María Gonzalez3Instituto de Botánica del Nordeste (UNNE-CONICET), Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste, Corrientes 3400, ArgentinaInstituto de Botánica del Nordeste (UNNE-CONICET), Facultad de Ciencias Exactas, Naturales y Agrimensura, Universidad Nacional del Nordeste, Corrientes 3400, ArgentinaInstituto de Botánica del Nordeste (UNNE-CONICET), Facultad de Ciencias Exactas, Naturales y Agrimensura, Universidad Nacional del Nordeste, Corrientes 3400, ArgentinaInstituto de Botánica del Nordeste (UNNE-CONICET), Facultad de Ciencias Agrarias, Universidad Nacional del Nordeste, Corrientes 3400, ArgentinaOver the past few decades, peanut smut, caused by <i>Thecaphora frezzii</i>, has evolved from an emerging disease to a major global threat to peanut production. However, critical knowledge gaps persist regarding the anatomical pathways and host responses involved in infection, colonization, and sporulation. This study examines the pathosystem and histopathology of the biotrophic phase of <i>T. frezzii</i> in the susceptible cv. Granoleico. Anatomical analyses were conducted using light microscopy, confocal laser scanning, and scanning electron microscopy. Our findings reveal that <i>T. frezzii</i> enters the host through the peg rather than the ovary tip, invading during the R2-subterranean phase. Fruit colonization occurs at the R3-stage when the mechanical layer between the mesocarp and endocarp has not yet formed. Hyphal entry into the seed takes place between the R3-medium and R3-late pod stages via the funiculus, leading to extensive seed coat colonization without penetrating the embryo. Once inside, hyperplasia and hypertrophy are triggered, coinciding with teliospore formation. Teliosporogenesis disrupts nutrient translocation, arresting embryo development. The hyphae colonize tissues intracellularly, utilizing living cells of the vascular bundles and following the peanut’s photoassimilate transport pathway. Investigating these structural responses in phenotypically contrasting peanut genotypes may provide key insights into the anatomical barriers and defense mechanisms that determine disease susceptibility and resistance, ultimately contributing to the development of resistant cultivars.https://www.mdpi.com/2223-7747/14/7/1083biotrophic fungihistopathologyhost-pathogen interactionpeanut (<i>Arachis hypogaea</i>)peanut smutteliosporogenesis |
| spellingShingle | María Florencia Romero Sergio Sebastián Samoluk José Guillermo Seijo Ana María Gonzalez Histopathology of <i>Thecaphora frezzii</i> Colonization: A Detailed Analysis of Its Journey Through Peanut (<i>Arachis hypogaea</i> L.) Tissues Plants biotrophic fungi histopathology host-pathogen interaction peanut (<i>Arachis hypogaea</i>) peanut smut teliosporogenesis |
| title | Histopathology of <i>Thecaphora frezzii</i> Colonization: A Detailed Analysis of Its Journey Through Peanut (<i>Arachis hypogaea</i> L.) Tissues |
| title_full | Histopathology of <i>Thecaphora frezzii</i> Colonization: A Detailed Analysis of Its Journey Through Peanut (<i>Arachis hypogaea</i> L.) Tissues |
| title_fullStr | Histopathology of <i>Thecaphora frezzii</i> Colonization: A Detailed Analysis of Its Journey Through Peanut (<i>Arachis hypogaea</i> L.) Tissues |
| title_full_unstemmed | Histopathology of <i>Thecaphora frezzii</i> Colonization: A Detailed Analysis of Its Journey Through Peanut (<i>Arachis hypogaea</i> L.) Tissues |
| title_short | Histopathology of <i>Thecaphora frezzii</i> Colonization: A Detailed Analysis of Its Journey Through Peanut (<i>Arachis hypogaea</i> L.) Tissues |
| title_sort | histopathology of i thecaphora frezzii i colonization a detailed analysis of its journey through peanut i arachis hypogaea i l tissues |
| topic | biotrophic fungi histopathology host-pathogen interaction peanut (<i>Arachis hypogaea</i>) peanut smut teliosporogenesis |
| url | https://www.mdpi.com/2223-7747/14/7/1083 |
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