First report of crown rot caused by fusarium redolens on wheat in Kazakhstan

Authors: BOZOGLU, TUGBA - Bolu Abant Izzet Baysal University; OZER, GOKSEL - Bolu Abant Izzet Baysal University; IMREN, MUSTAFA - Bolu Abant Izzet Baysal University; Paulitz, Timothy; DABAAT, ABDELFATTAH - International Maize & Wheat Improvement Center (CIMMYT)

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/26/2021
Publication Date: 5/26/2021
Citation: Bozoglu, T., Ozer, G., Imren, M., Paulitz, T.C., Dabaat, A.A. 2021. First report of crown rot caused by fusarium redolens on wheat in Kazakhstan. Plant Disease. https://doi.org/10.1094/PDIS-01-21-0015-PDN.
DOI: https://doi.org/10.1094/PDIS-01-21-0015-PDN

Interpretive Summary: Fusarium redolens was isolated from diseased wheat crowns in Kazakhstan, It was identified with molecular techniques, and reinoculated onto healthy wheat plants in greenhouse experiments. It caused stunting and brown discoloration of the wheat, indicating that this fungus could be a pathogen on wheat in Kazakhstan.

Technical Abstract: Fusarium crown rot, caused by a fungal complex of the genus Fusarium, is a major constraint that results in significant losses in wheat production worldwide. In 2019, diseased wheat plants with typical symptoms of crown rot such as discoloration on the first two or three internodes of the stem just above the soil line and stunted, dry rotted, and discolored roots were collected in several wheat fields in Kazakhstan. Symptomatic tissues were surface sterilized 1% NaClO solution for 2 min, rinsed with sterile distilled water three times, air-dried in a laminar flow cabinet, transferred to Petri dishes containing 1/5 strength potato dextrose agar (PDA), and incubated in the dark at 23°C for 5 days. Seventy-nine single-spore isolates showed cultural and microscopic characteristics of Fusarium oxysporum were derived and transferred to PDA and Spezieller-Nährstoffarmer agar (SNA). Colonies were initially white, but with age, and produced a beige to pink discoloration in the PDA. Microconidia formed on aerial monophialides were hyaline, with 0 to 1 septum, oval- to kidney-shaped, and measured 4.3 to 10.3 × 1.9 to 3.4 (average 7.8 × 2.6) µm. Macroconidia were straight to slightly curved, 3 to 5 septate, and measured 18.7 to 38.8 × 2.9 to 6.6 (average 29.9 × 4.7) µm, with typically foot-shaped basal cells. Chlamydospores were present in PDA. The sequence analysis based on portions of translation elongation factor 1a (EF-1a) and the internal transcribed spacer (ITS) loci with primers EF1/EF2 (O’Donnell et al. 1998) and ITS1/ITS4 (White et al. 1990) identified 29 of the 72 isolates as Fusarium redolens Wollenw. A BLAST search of EF1-a (Accession Nos. MW403914-MW403918) and ITS (Accession Nos. MW397138-MW397142) sequences of representative five isolates showed 100% identity to those of F. redolens strains available in GenBank (e.g., GU250584 and MT435063). To confirm the pathogenicity of the five isolates, five pre-germinated seeds of wheat cultivar Seri 82 were placed in a 9-cm-diameter pot filled with a sterile mixture substrate containing equal volumes of peat, vermiculite, and soil. Approximately 1-cm-diameter 7-day-old mycelial plugs of the isolate were placed in contact with the seeds. The seeds were covered with the same mixture substrate, and then the pots were placed in a growth chamber at 23°C with a 12-h photoperiod. The experiment was conducted twice with three replicate 15-cm pots with 10 plants per pot. Controls were inoculated with sterile agar plugs using the same procedure. After four weeks, all the inoculated plants showed a weak growth with brown discoloration in most parts of the crown and root, whereas no symptoms were observed in the control plants. To fulfill Koch’s postulatesSubsequently, the pathogen isolate was reisolated from the crowns of diseased plants and morphologically identified based on the methods described above. morphology described above to fulfill Koch’s postulates. This is the first report of F. redolens causing crown rot of wheat in Kazakhstan. Certainly, several morphological and microscopic similarities are present between F. oxysporum and F. redolens., Baayen et al. (2001), however, has shown that F. redolens isolates were quite distinct from F. oxysporum isolates using molecular tools. The pathogen was previously reported in the Fusarium species complex associated with crown rot of wheat in Turkey (Gebremariam et al. 2015) and (Taheri et al. 2011) in Canada. This pathogen may pose a risk for wheat production in Kazakhstan.