First report of Fusarium hostae causing crown rot on wheat in Azerbaijan

Authors: OZER, G. - Abanat Izzet Baysal University; IMREN, M. - Ankara University Of Turkey; BAYRAKTAR, H. - Ankara University Of Turkey; Paulitz, Timothy; MUMINJANOV, H - Food And Agriculture Organization Of The United Nations (FAO); DABABAT, A. - International Maize & Wheat Improvement Center (CIMMYT)

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/3/2019
Publication Date: 12/10/2019
Citation: Ozer, G., Imren, M., Bayraktar, H., Paulitz, T.C., Muminjanov, H., Dababat, A.A. 2019. First report of Fusarium hostae causing crown rot on wheat in Azerbaijan. Plant Disease. 103(12):3278. https://doi.org/10.1094/pdis-05-19-1035-pdn.
DOI: https://doi.org/10.1094/pdis-05-19-1035-pdn

Interpretive Summary: Fusarium hostae was isolated from diseased wheat in Azerbaijan for the first time and shown to cause crown rot of wheat.

Technical Abstract: In June 2017, 76 fields in the main bread wheat (Triticum aestivum L.) and durum wheat (Triticum durum Desf.) growing regions of Azerbaijan were surveyed to identify the fungi causing crown and root rot. Diseased plants were collected at the stage of near maturity, maturity and/or after harvest. For each field, 20-30 tillers of wheat in a 5-ha area were randomly sampled put in paper bags and transported to the laboratory. The crown, root, and stem base tissues of each plant were rinsed with tap water to remove soil particles and examined for lesions. 3-cm sections of symptomatic tissues were surface disinfested with 1% NaOCl for 1 min, rinsed with sterile distilled water, and air dried on sterilized filter paper. Dried sections were chopped into 1-cm lengths and placed on 1/5 strength potato dextrose agar (PDA) amended with streptomycin (0.1 g/L) and chloramphenicol (0.05 g/L). Following five days of incubation in the dark at 20°C, Fusarium-like colonies were purified using the single spore isolation method and then transferred on new media and incubated at 20 °C for 10 days to evaluate for conidia and chlamydospores (Leslie and Summerell 2006). The primer pairs EF1/EF2 described by O’Donnell et al. (1998) were used to amplify translation elongation factor 1- alpha (EF1-a) locus for representative Fusarium spp. isolates. Amplified DNA was subjected to bidirectional sequencing (Macrogen, Inc., Seoul, Korea). Morphologically and molecular investigation revealed that out of 439 Fusarium spp. isolates, 11 isolates from six fields in Ismailli and Oguz locations were identified as F. hostae. Nucleotide BLAST similarity analysis of the sequences of two isolates showed 99-100% homology with the EF1-a sequence of F. hostae strain NRRL 29889 (AY329034) and deposited in GenBank (Accession Nos. MK577923 and MK590116). Isolates exhibited white to purplish coloration and aerial mycelial growth on PDA. Microconidia (n=50) were hyaline, oval to kidney shaped, usually aseptate but rarely with 1 transverse septa, and measured 2.1 to 3.9 × 4.7 to 10.6 µm while macroconidia (n=50) were abundant, hyaline, fusiform, with a foot shaped basal cell, with two to four septa (generally 3) and measured 2.9 to 4.8 × 24.2 to 46.2 µmTo test for pathogenicity, five pre-germinated seeds of cv. Seri 82 were placed onto a sterile mixture substrate of peat, vermiculite, and soil (1:1:1, v/v/v) in 9-cm diameter plastic pots (17 cm long). The mycelial plugs of isolates of F. hostae were removed from the margins of actively growing PDA plates and put around the wheat seedlings and covered with the mixture substrate, while sterile agar plugs were used for controls. The pathogenicity test was repeated two times with on 15 replicated seeds (five seeds per pots) for each isolate in a growth chamber with a 12-h photoperiod at 24°C. After six weeks of inoculation, crown browning and necrosis occurred in the inoculated plants, while no symptoms were observed in the control plants. The pathogen was reisolated from the crowns of diseased plants and identified by the method described above to fulfill Koch’s postulates. To our knowledge, this is the first report of F. hostae causing crown rot on wheat in Azerbaijan. The pathogen was previously identified in Turkey associated with the crown rot of wheat with an isolation frequency of 5.9% among Fusarium isolates.