Abstract
BackgroundWheat is the main cultivated crop and the highest cereal used up by humans in Iraq. Two Fusarium species causing Fusarium head blight (FHB) disease on wheat has been detected only in the middle of Iraq, and Fusarium crown rot (FCR) disease has been detected in several provinces, but it was limited to only three species. This study was conducted to deepen and enlarge our current understanding of the causal agents of these symptoms observed in the wheat fields and to isolate, purify, and identify (molecularly) the most common soil fungi occurring in the rhizosphere of seedlings showing, root, crown, stem, and head at symptom occurrence.ResultsEighty-eight Fusarium isolates were isolated from 7 wheat cultivars planted in 14 fields in the south of Iraq, Basra province, by using polymerase chain reaction (PCR) technique. Based on molecular identification methods as well as the analysis of phylogenetic trees, the results of this study have verified that the main species belonging to the genus Fusarium causing FHB and FCR diseases on wheat in the studied areas are F. pseudograminearum, F. graminearum, F. equiseti, F. culmorum, F. solani, F. avenaceum, F. chlamydosporum, F. cerealis, and F. nygamai. The first 3 species have been identified previously in several Iraqi studies on wheat and barley. This is the first record of the last 6 Fusarium species from the wheat crop in Iraq as causative pathogens of FHB and FCR. Individual phylogenetic trees of 71 Fusarium isolates reconstructed based on the internal transcribed spacer (ITS) sequences showed that all isolates belonging to each of the 9 Fusarium species form monophyletic groups with identical isolates of the same species. Collective phylogenetic tree of the remaining 17 Fusarium isolates reconstructed based on translation elongation factor 1 alpha (TEF1-α) gene sequences showed that all isolates belonging to each of the 4 Fusarium species forms monophyletic groups with identical isolates of the same species.ConclusionIraqi wheat cropping system is seriously threatened by FHB and FCR diseases. Other Iraqi provinces should be inspected to understand the distribution of both diseases.
Highlights
Molecular identification based on ITS1 and ITS4 primer pairs Established upon the closest identification of BLAST analysis, the obtained nucleotide sequences of 123 isolates were compared to the GenBank databases and matched at diverse global similarity
Our results of morphological investigation in association with DNA sequencing consistent with the first matching identification of BLAST sequence database in NCBI using distinct sequences proved the identity of 88 isolates out of the total 123 isolates that belong to the genus Fusarium in 9 species (F. pseudograminearum, F. graminearum, F. culmorum, F. chlamydosprum, F. equiseti, F. solani, F. avenaceum, F. cerealis, and F. nygamai)
Seventy-one sequences of these isolates corresponded to the GenBank databases at 97–100% as global similarity (Additional file 1), whereas the remaining 17 Fusarium isolate sequences were matched to the published sequences that deposited in the GenBank sequence database in less than 97% of similarity with high expected values and inadequate maximum scores
Summary
Bread wheat is the main cultivated crop and the highest cereal used up by humans in Iraq. Multiple Fusarium species are responsible for the two destructive wheat diseases: Fusarium head blight (FHB) and Fusarium crown rot (FCR). These two diseases are the most widespread cereal diseases that have presented in most regions all over the world. Wheat is the main cultivated crop and the highest cereal used up by humans in Iraq. Two Fusarium species causing Fusarium head blight (FHB) disease on wheat has been detected only in the middle of Iraq, and Fusarium crown rot (FCR) disease has been detected in several provinces, but it was limited to only three species. This study was conducted to deepen and enlarge our current understanding of the causal agents of these symptoms observed in the wheat fields and to isolate, purify, and identify (molecularly) the most common soil fungi occurring in the rhizosphere of seedlings showing, root, crown, stem, and head at symptom occurrence
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