Microscope examination further showed that the microtubule polymerization was reduced in Fg Stu2-Si mutants, which could account for the aberrant morphology. Moreover, the Fg Stu2 promoter replacement mutants ( Fg Stu2-Si mutants) produced twisted hyphae and decreased growth rate. Besides, Fg Stu2 could also interact with Fg γ-tubulin and presumed Fg Ndc80, which suggested that the Fg Stu2 gene might associate with microtubule nucleation and kinetochore-microtubule attachments like Dis1/Stu2/XMAP215 homologs in other species. Co-localization experiment and co-immunoprecipitation (Co-IP) assay demonstrated that Fg Stu2p is a microtubule associated protein. Here, we identified and investigated the Dis1/Stu2/XMAP215 homolog (FGSG_10528) in Fusarium graminearum ( Fg Stu2p). However, function of Dis1/Stu2/XMAP215 homolog in plant pathogenic fungi has not been determined. The conserved Dis1/Stu2/XMAP215 microtubule association proteins (MAPs) family plays an important role in microtubule dynamics, nucleation, and kinetochore-microtubule attachments. Differential interference contrast images of conidia stained with calcofluor white (CFW) were captured with an electronic microscope. DFgEB1 produced more curved conidia in CMC liquid medium after 4 days in a shaker in comparison with PH-1 and DFgEB1-C. Bars with the same letter indicate no significant different according to a Fisher's least significant difference (LSD) test at P 5 0.05. Conidia were quantified using a hemacytometer after incubation of each strain in CMC for 4 days.
Deletion of FgEB1 led to increased conidiation.
The mutant produced wavy hyphae with increased branching. Hyphal tip morphology and branching patterns of PH-1, DFgEB1 and DFgEB1-C grown on PDA plates. Comparisons in colony morphology among the wild-type PH-1, FgEB1 deletion mutant DFgEB1 and the complemented transformant DFgEB1-C grown on solid media PDA, CM, MM and wheat-head at 258C for 3 days. All rights reserved.įgEB1 modulates polar growth of hypha and conidium in F. graminarum, which provides a novel insight into understanding of the biological functions of EB1 in filamentous fungi. Taken together, results of this study indicate that FgEB1 regulates cellular polarity, fungicide sensitivity and DON biosynthesis via different interactors in F. In addition, the deletion of FgEB1 led to dramatically decreased deoxynivalenol (DON) biosynthesis. Interestingly, FgEB1 and FgKar9 constituted another complex that modulated the response to carbendazim, a microtubule-damaging agent specifically. On the other hand, we identified four core septins as FgEB1-interacting proteins, and found that FgEB1 and septins regulated conidial polar growth in the opposite orientation. In addition, the lack of FgEB1 also altered the distribution of polarity-related class I myosin via the interaction with the actin. Microscopic examination further showed that the microtubules of ΔFgEB1 exhibited less organized in comparison with those of the wild type. Here, we observed that the FgEB1 deletion mutant (ΔFgEB1) of Fusarium graminearum exhibits twisted hyphae, increased hyphal branching and curved conidia, indicating that FgEB1 is involved in the regulation of cellular polarity. However, functions of EB1 orthologs in plant pathogenic fungi have not been characterized yet. In yeasts, the end-binding protein 1 (EB1) homologs regulate microtubule dynamics, cell polarization, and chromosome stability.
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