Abstract

CHAVARRO-MESA, Edisson et al. Genetic diversity of Rhizoctonia solani AG-3PT, the etiological cause of stem canker and black scurf in Colombian potatoes. Cienc. Tecnol. Agropecuaria [online]. 2021, vol.22, n.3, e1888.  Epub Aug 31, 2021. ISSN 0122-8706.  https://doi.org/10.21930/rcta.vol22_num3_art:1888.

Stem canker and black scurf are potato diseases caused by the fungus Rhizoctonia solani, anastomosis group 3 (AG-3PT). This fungus affects potato roots, stems, and tubers, reducing crop yields. This study aims to determine the genetic diversity of R. solani AG-3PT obtained from the Colombian departments of Antioquia, Boyacá, and Cundinamarca. Restriction fragment length polymorphism (RFLP) analysis of the ITS-5.8S ribosomal DNA region allowed the differentiation and specific identification of AG-3PT and AG2-1 anastomosis groups. These results confirm that AG-3PT is the primary causative agent and etiological origin of stem canker and black scurf in Colombia. Two distinct subgroups within R. solani AG-3PT were identified using random amplified microsatellite markers (RAMs); AG-3PT (A) shares a similarity index of 78 %, and AG-3PT (B) shares a similarity of 79 % among its isolates. These subgroups were not linked to a geographical origin but to the AG group to which they belong. Nei’s genetic diversity [D] of 0.25 confirmed the high genetic diversity for AG-3PT through RAMs analysis, related to a high evolutive potential within the AG-3PT group in Colombia. Finally, the R. solani AG-3PT fungus obtained from Cundinamarca had the adaptative potential to emerge as a pathogen of Solanum phureja in Colombia, possibly due to the similarity between pathosystems.

Keywords : random amplified microsatellites (RAMs); ribosomal DNA; Solanum phureja; Solanum tuberosum; Thanatephorus cucumeris.

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