First Report of Epicoccum blight disease Caused by Epicoccum latusicollum on sugarcane in Brazil

Sugarcane (Saccharum officinarum L.) is one of the most important crops in the world. However, several factors can interfere with production, including the occurrence of diseases. In February 2024, symptoms of leaf blight were observed in the CTC4 and RB92579 cultivars in sugarcane fields located in the city of Carpina, in the state of Pernambuco, Brazil (7° 3’0.776” S / 35°14’16.555” W). The symptoms initially observed included leaf blight and slight leaf rolling. The burn displayed a straw-colored appearance with reddish borders and progressed in a v-shape, producing visible fungal fruiting bodies on the lesions. The incidence of symptoms was estimated to range between 70 and 80%. Symptomatic leaves, of ten plants were collected, in an area of ​​five hectares, but a similar symptom occurs in a large area of ​​sugarcane cultivation on the coastal strip of Brazilian northeastern. The possible causal agent was isolated using an indirect method on potato dextrose agar (PDA) culture medium. Plates were incubated at 28°C, and after seven days of cultivation, the colonies on PDA displayed a reddish-brown color, with dense growth of compact aerial mycelia, a felty appearance with white to pink coloration, and forming several mycelial pellets with the same coloration, visible on the underside. The chlamydospores were brown, uni- or multicellular, measuring 12.5 to 25.8 x 9.8 to 21.5 µm (n = 60). The pycnidia were dark brown to brown, predominantly semispherical, measuring 96 to 118.39 x 64 to 111 µm (n = 10). The conidia were ellipsoidal, hyaline, and aseptate, measuring 4.56 to 6.11 x 1.56 to 2.57 µm (n = 50). The morphological characteristics were similar to those of Epicoccum latusicollum (Chen et al. 2017). From the isolation, ten strains were obtained and deposited in the microorganism culture collection at the Plant Pathology Laboratory of the Sugarcane Experimental Station in Carpina–CMLABFITO, from all plants collected with symptoms, strains were obtained, however, two strains were randomly selected used for characterization in this work. To verify the pathogenicity of the (CMLABFITO 2.17 and CMLABFITO 2.18), 60-day-old plants of the CTC4 variety were inoculated with 10 mL of the conidial suspension (106 conidia/ mL) per plant using a manual sprayer until runoff. Four replicates per isolate were used, each containing two plants. Sterilized distilled water was used as a negative control. The plants were maintained in a humid chamber for 48 h at 28°C. The experiment was repeated twice. Eight days after inoculation, the plants exhibited subtle tip burn on the leaves, and the symptoms progressed over time. No symptoms were observed in the control plants. Koch's postulates were fulfilled through the reisolation of the isolates from the lesions. The reisolated fungus corresponded morphologically to the inoculated pathogen. For molecular identification of the pathogen, internal transcribed spacer (ITS) of region of ribosomal RNA (rDNA), as well as the β-tubulin (TUB2) and Actin (ACT) genes were amplified by PCR and sequenced using the Sanger method (Sanger et al. 1977). The sequences were deposited in GenBank database, ITS sequences (GenBank accession PQ412528 and PQ412529), TUB2 sequences (GenBank accession PQ416614 and PQ416615) and Actin gene sequences (GenBank accession PV178719 and PV178720) for CMLABFITO 2.17 and CMLABFITO 2.18, respectively. For sequences obtained from strain CMLABFITO 2.17, the ITS sequence showed identity 99.05% (438/441), TUB2 showed identity 99.32% (415/419) with E. latusicollum and ACT showed identity 100% to E. sorghinum. For sequences obtained from strain CMLABFITO 2.18 the ITS sequence showed identity 99.31% (432/435), TUB2 showed identity 100% (458/458) to E. latusicollum and ACT showed identity 100% to E. sorghinum. For actin the only closest sequeces available on NCBI belong to the E. sorghinum, because do not exist actin sequences from E. latusicollum on database. The phylogenetic analysis showed a very defined clade comprising CMLABFITO 2.17, CMLABFITO 2.18 and worldwide E. latusicollum strains. E. latusicollum has been reported causing disease in other plants, such as banana, Curcuma kwangsiensis and Hemerocallis citrina (Li et al. 2023; Liu et al. 2023; Wang et al. 2023). This is the first report of E. latusicollum causing leaf blight in sugarcane in Brazil.