First report of Fusarium madaense as a cause of root and stalk rot on Sorghum bicolor in Australia

Sorghum (Sorghum bicolor) is mainly grown for stock feed in eastern Australia where significant economic losses result from diseases caused by Fusarium spp. (Petrovic et al., 2009; Kelly 2017). During the 2018 sorghum growing season, 66 plants showing symptoms typical of infection were randomly collected three fields Barramornie (27.08○N, 150.11°E), southern Queensland. isolates obtained surface-sterilised stem or root pieces (1 cm) placed on Fusarium-selective PCNB media (Leslie & Summerell, 2008) and incubated at 23°C five days. Ninety single-spore cultures sub-cultured potato dextrose agar (PDA) molecular characterisation 17 these deposited into Queensland Plant Pathology Herbarium (BRIP, Brisbane, Australia). One isolate (BRIP 75161a) recovered a diseased node was identified as F. madaense DNA barcodes. Comparison partial gene sequences RNA polymerase II largest subunit (rbp1), second (rbp2), translation elongation factor 1-alpha (tef-1α) (GenBank Accession Nos. OQ695493, OQ657300 OQ657299, respectively) BRIP 75161a showed 100%, 100% 99.7% nucleotide identities with (ex-type: CBS 146669), respectively. The polyphasic identification tool Mycobank FUSARIOID-ID database (https://www.mycobank.org) using same genes confirmed identity 99.9% to 146669). Phylogenetic analysis rbp1, rbp2 tef-1α, closely related species (F. andiyazi, madaense, mirum, musae, verticillioides) (Costa 2021a) resulted clustering ex-type strain reference well-supported clade (Figure 1). Colonies synthetic nutrient-poor carnation leaf white infrequent areal mycelium without pigmentation 2), while PDA they powdery floccose abundant whitish aerial mycelia, becoming violet. Microconidia cylindrical narrowly ellipsoidal obovoid, 0–4 septate, 6–16 × (1.5–) 2–4.5 μm, hyaline, produced false heads 3) long chains. Pathogenicity assessed 10-day-old seedlings S. bicolor cv. Resolute. plant per pot sterile vermiculite inoculated an plug (0.5 (Kelly Each experiment consisted replicates conducted times. Reddish black discolouration infected roots observed 4). Control non-colonised did not develop Koch's postulates completed reisolating fungus tissues (10 days post inoculation) comparing cultural morphology PDA. causes stalk rot sorghum, maize, millet, pokkah boeng sugarcane 2021a). It first isolated groundnut Nigeria (Ezekiel 2020) later several tropical countries 2021b). This report Australia. work carried out part project funded Broadacre Cropping Initiative Queensland,