Departamento de Fitopatologia, Universidade Federal de Viçosa, 36570-900 Viçosa, MG, Brazil.
Departamento de Fitopatologia, Universidade Federal de Lavras, 37200-000 Lavras, MG, Brazil.
Int J Food Microbiol. 2019 Oct 2;306:108267. doi: 10.1016/j.ijfoodmicro.2019.108267. Epub 2019 Jul 13.
Fusarium incarnatum-equiseti species complex (FIESC) is commonly detected in Brazilian rice, but knowledge of the species limits and their toxigenic potential is lacking. Seventy strains morphologically identified as FIESC-like, isolated from the major rice-growing regions of Brazil, were subjected to sequencing of EF-1α gene. Among them, 18 strains were selected and analyzed for their RPB2 gene sequences. Nine phylogenetic species were identified, among which eight matched the previously reported FIESC 4 (F. lacertarum), 6, 16, 17 (F. pernambucanum), 20 (F. caatingaense), 24, 26 and 29. One new phylogenetic species was identified, and named FIESC 38. Five strains formed new singleton lineages. The most dominant species were FIESC 26 (22/70 strains) and FIESC 38 (21/70), the newly identified species. The incarnatum morphotype was dominant (10 phylogenetic species) over the equiseti (4 species). Among 46 strains selected to represent all species, only 16 strains produced detectable levels of mycotoxins in vitro. FIESC 26 produced ZEA and FIESC 38 produced both ZEA and DON. ZEA was produced by nine isolates of three other species, among which few isolates produced trichothecenes: DON (5/46), NIV (3/46), 4-ANIV (2/46), 15-ADON (1/46) and 3-ADON (1/46). The T-2 and HT-2 mycotoxins were not detected. Our results contribute novel information on species limits and mycotoxin production within cereal-infecting FIESC in the southern hemisphere and provide baseline data for further exploring morphological differences among the species.
镰刀菌互生单端孢霉复合种（FIESC）在巴西大米中经常被检测到，但对其种的限制和产毒潜力的了解却很有限。从巴西主要稻米种植区分离出的 70 株形态上与 FIESC 相似的菌株，进行了 EF-1α 基因测序。其中，选择了 18 株进行 RPB2 基因序列分析。鉴定出 9 个种的单倍型，其中 8 个与先前报道的 FIESC 4（F. lacertarum）、6、16、17（F. pernambucanum）、20（F. caatingaense）、24、26 和 29 相匹配。一个新的种被鉴定出来，命名为 FIESC 38。5 株形成新的单系。最优势的种是 FIESC 26（22/70 株）和 FIESC 38（21/70 株），这两种都是新鉴定的种。 incarnatum 形态型（10 个种）比 equiseti 形态型（4 个种）更为优势。在所选择的代表所有种的 46 株菌株中，只有 16 株在体外产生可检测水平的真菌毒素。FIESC 26 产生 ZEA，FIESC 38 同时产生 ZEA 和 DON。ZEA 由三个其他种的 9 个分离株产生，其中少数分离株产生了三烯化合物：DON（5/46）、NIV（3/46）、4-ANIV（2/46）、15-ADON（1/46）和 3-ADON（1/46）。未检测到 T-2 和 HT-2 真菌毒素。我们的结果提供了有关南半球谷类感染 FIESC 种的界限和产毒潜力的新信息，并为进一步探索种间形态差异提供了基线数据。
