Abstract. Mohammed-Ameen MK, Minati MH, Abbas MH. 2021. Morphogenetic identification, description and pathogenicity of novel pathogens on Iraqi Wheat Plant (Triticum aestivum) causing head blight and crown rot diseases. Biodiversitas 22: 2999-3005. Wheat (Triticum aestivum L.) plant suffers from several fungal diseases, such as Fusarium head blight, root rot, and crown rot diseases that reduce the quality and quantity of grains. Two Fusarium species (Fusarium brachygibbosum and F. falciforme) have been isolated from wheat roots and rhizosphere regions showing disease symptoms in wheat fields in Al-Hwuir and Al-Qurna districts at Basra province. Each fungal species had been characterized morphologically and molecularly based on DNA sequence data for the translation elongation factor 1- ? (TEF-1 ?). Results of pathogenicity test showed that F. falciforme and F. brachygibbosum at the third week of inoculation induced head bleached symptoms with the severity of 12.46% (with significant differences P > 0.05) and 7.14%, respectively on Abu Ghraib 3 cultivar. Yellowing and necrosis symptoms were recorded in stem and crown region. The mean of disease severity (as necrosis on basal stem and crown) was 5% and 3.34% for F. falciforme and F. brachygibbosum, respectively. The two Fusarium species were identified as new pathogens on wheat plants in Iraq, causing head bleaching, stem and crown necrosis.

Background: 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. Results: Eighty-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. Conclusion: Iraqi wheat cropping system is seriously threatened by FHB and FCR diseases. Other Iraqi provinces should be inspected to understand the distribution of both diseases.

This study was conducted to survey the fungal microflora in winter wheat (Triticum aestivum L.), ear, stem, root, seed and field soil in 17 field distributed on Basra province, Iraq. The mycoflora of plant parts, seeds and soil were determined morphologically and molecularly. In total 46 genera with 66 species of different fungal groups were found. The prevalent fungal group on all examined sources was the anamophic Ascomycota (85.34%), followed by Zygomycota (5.46%). Telemorphic Ascomycota was only at (3.64%) and Basidiomycota was in less than (1%). Aspergillus, Penicillium, and Fusarium were the dominant genera in soil and rhizosphere region. The same genera were found in seed but Alternaria was instead of Fusarium. The fungal diversity in plant parts was different, as Alternaria, Fusarium, Helminthosporium, Cladosporium, Penicillium and Aspergillus genera were more occurrence. The highest total fungal population was observed in rhizosphere region and soil, and the lowest was in wheat head. The occurrence of collective fungal community was almost identical in wheat seed, root and stem.

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This study was conducted to evaluate the interaction between disease incidence of both Fusarium head blight (FHB) and crown rot (FCR) and physiochemical parameters for soil samples and environmental factors in 14 selected wheat fields in the North of Basra province. The results showed that both diseases were occurred in all surveyed fields. The level of FCR incidence was higher than FHB. The incidence of both diseases was increased with favourable weather conditions (high humidity and temperature ˃15 °C), reaching the highest levels in crucial periods before and during the ripening stage. The percentage of disease incidence ranged between 6 to 71% and 3 to 54% for FCR and FHB, respectively. Nine physiochemical parameters of soil were examined in this study, but only soil organic carbon (SOC) (P< 0.0000), soil organic matter (SOM) (P< 0.0000) and Cation exchange capacity (CEC) (P< 0.0008) and (P< 0.0002) had highly significant differences among the selected wheat fields in the occurrence of disease incidence for FHB and FCR respectively. The values were ranged between 0.33-1.27% for SOC, 0.66-2.54% for SOM and 10.08-20.59 mg/100g for CEC. Favourable weather conditions and poor soils with SOM, SOC and CEC contents were found to be great factors for encouraging both diseases during this study.