Occurrence and distribution of Streptomyces species causing potato scab in Brazil - Characterization of two new species Streptomyces pococaldensis sp. nov. and Streptomycesshimoyamaii sp. nov.

Potato scab, caused by species of the genus Streptomyces is a significant disease affecting potato production worldwide, leading to economic losses. This study aimed to investigate the occurrence and distribution of Streptomyces species associated with potato scab in Brazil and to characterize two new species. A total of 91 Streptomyces strains were isolated from symptomatic potato tubers collected across seven states. Morphological, molecular, and pathogenicity assays were performed to classify the isolates. The identification of Streptomyces species was carried out using PCR-RFLP of the atpD gene, sequencing of housekeeping genes, and multilocus sequence analysis (MLSA). Phylogenetic analysis confirmed that two strains, IBSBF 2435T and IBSBF 2507T, represent novel species. Genome sequencing and in silico DNA-DNA hybridization further supported their classification as distinct taxa. The study highlights the presence of pathogenic Streptomyces species in Brazilian potato fields, underscoring the importance of accurate identification for disease management. The characterization of new species expands knowledge on the diversity of phytopathogenic Streptomyces and provides valuable data for further studies on their pathogenic mechanisms and control strategies. According to the data, IBSBF 2435ᵀ and IBSBF 2507ᵀ represent two new Streptomyces species related to potato scab. The proposed names for these strains are Streptomyces pococaldensis sp. nov. (IBSBF 2435ᵀ = CBMAI 2707ᵀ = ICMP 24293ᵀ = MUM 22.66ᵀ) and Streptomyces shimoyamaii sp. nov. (IBSBF 2507ᵀ = CBMAI 2709ᵀ = ICMP 24295ᵀ = MUM 22.64ᵀ).