A megabirnavirus alleviates the pathogenicity of Fusarium pseudograminearum to wheat

2021 ◽  
Author(s):  
Yuan Xie ◽  
Zhifang Wang ◽  
Ke Li ◽  
Dongwei Liu ◽  
Yifan Jia ◽  
...  

Fusarium pseudograminearum is a phytopathogen that causes wheat crown rot disease worldwide. Fusarium pseudograminearum megabirnavirus 1 (FpgMBV1) was isolated from the hypovirulent strain FC136-2A of F. pseudograminearum as a novel dsRNA mycovirus belonging to the family Megabirnaviridae. Here we examined the effects of FpgMBV1 on colony morphology and pathogenicity of F. pseudograminearum. Through hyphal tip culture, we obtained virus-free progeny of strain FC136-2A, referred to as FC136-2A-V-.FpgMBV1 was transferred horizontally to another virus-free strain, WZ-8A-HygR-V-. The progeny that obtained through horizontal transfer was referred to as WZ-8A-HygR-V+. Colony morphology was similar between the FpgMBV1-positive and -negative strains. The ability to penetrate cellophane in vitro was lost and pathogenicity on wheat plants was reduced significantly in the FpgMBV1-positive strains relative to the FpgMBV1-negative strains. Microscopic observations showed a 6-h delay in the formation of appressoria-like structures in FC136-2A relative to FC136-2A-V-. And mycelium extension was significantly longer in wheat coleoptiles infected by WZ-8A-HygR-V- than in that infected by WZ-8A-HygR-V+ at 12 and 20 hours after inoculation (HAI). In addition, expression of five genes that encode cell wall-degrading enzymes differed significantly between FpgMBV1-positive and -negative strains at 12 and 20 HAI during early infection of wheat cells by conidia. This study provides evidence for the hypovirulence effect of FpgMBV1 on F. pseudograminearum and suggests that the underlying mechanism involves unsuccessful early infection and perhaps cell wall degradation.

2017 ◽  
Vol 27 (1) ◽  
pp. 22-28 ◽  
Author(s):  
Darshna G. Hirpara ◽  
Harsukh P. Gajera ◽  
Hitesh Z. Hirpara ◽  
Balubhai A. Golakiya

The fungus <i>Trichoderma</i> is a teleomorph of the <i>Hypocrea</i> genus and associated with biological control of plant diseases. The microscopic, biochemical, and molecular characterization of <i>Trichoderma </i>was carried out and evaluated for in vitro antagonistic activity against the fungal pathogen <i>Sclerotium rolfsii</i> causing stem rot disease in groundnut. In total, 11 isolates of <i>Trichoderma</i> were examined for antagonism at 6 and 12 days after inoculation (DAI). Out of 11, <i>T. virens </i>NBAII Tvs12 evidenced the highest (87.91%) growth inhibition of the test pathogen followed by <i>T. koningii</i> MTCC 796 (67.03%), <i>T. viride </i>NBAII Tv23 (63.74%), and <i>T. harzianum </i>NBAII Th1 (60.44%). Strong mycoparasitism was observed in the best antagonist Tvs12 strain during 6-12 DAI. The specific activity of cell wall-degrading enzymes - chitinase and β-1,3-glucanase - was positively correlated with growth inhibition of the test pathogen. In total, 18 simple sequence repeat (SSR) polymorphisms were reported to amplify 202 alleles across 11 <i>Trichoderma </i>isolates. The average polymorphism information content for SSR markers was found to be 0.80. The best antagonist Tvs 12 was identified with 7 unique SSR alleles amplified by 5 SSR markers. Clustering patterns of 11 <i>Trichoderma </i>strains showed the best antagonist <i>T. virens</i> NBAII Tvs 12 outgrouped with a minimum 3% similarity from the rest of <i>Trichoderma.</i>


2020 ◽  
Author(s):  
Yuan Xie ◽  
Zhifang Wang ◽  
Ke Li ◽  
Dongwei Liu ◽  
Yifan Jia ◽  
...  

Abstract Background: Fusarium pseudograminearum is the predomenant causal agent of devastating crown rot diseases in cereal crops around the world. Mycoviruses have attracted increasing attention as potential biological control agents on plant diseases. The unique mycoviruse isolated from F. pseudograminearum is Fusarium pseudograminearum megabirnavirus 1 (FpgMBV1), which is a new member of the family Megabirnaviridae. To determine the hypovirulence effects of FpgMBV1 on F. pseudograminearum to wheat plants is critical for the potential application of FpgMBV1 in the control of cereal crown rot disease. Methods: Hyphal tip cultures were conducted to obtain a FpgMBV1-free strain, named as FC136-2A-V-. A hyg gene was transformed into a highly virulent virus-negative stain WZ-8A of F. pseudograminearum to obtain the deduced strain WZ-8A-HygR-V-. WZ-8A-HygR-V- was used in pairing culture with the FpgMBV1-carrying F. pseudograminearum strain FC136-2A to obtain a FpgMBV1-positive strain WZ-8A-HygR-V+. Then the two pairs of strains, FC136-2A-V-/FC136-2A and WZ-8A-HygR-V-/WZ-8A-HygR-V+, were used to determine the potential effect on F. pseudograminearum by the infection of FpgMBV1 through tests on the growth, sensitivity to stress and cellophane penetrating ability in vitro and the pathogenicity to wheat plants.Results: FpgMBV1 could be cured by hyphal tip culture and horizontally transferred between F. pseudograminearum strains through pairing culture. Reduction of FpgMBV1-carrying strains on hyphal growth were found under the treatment of 0.5% SDS. No differences in the growth rates of tested strains in the treatments with 1 M NaCl, 1 M KCl, or 15 mM H2O2. Comparing to virus-negative strains, the In vitro cellophane penetrating ability was lost in FpgMBV1-carrying strains. The disease index of wheat plants inoculated with FC136-2A-V- was significantly higher than that inoculated with FC136-2A, while the pathogenicity of WZ-8A-HygR-V+ reduced significantly comparing to that of WZ-8A-HygR-V-.Conclusions: FpgMBV1 is the causal agent of the low pathogenicity to wheat plants of its original host F. pseudograminearum strain FC136-2A. And FpgMBV1 could be horizontally transferred to another F. pseudograminearum strain and reduce its pathogenicity to wheat plants.


2021 ◽  
Vol 13 (1) ◽  
pp. 69-80
Author(s):  
Majida Hadi Mahdi Alsaady ◽  
Hussein Ali Salim ◽  
Rakib A. Al-ani ◽  
Hadi M. Aboud ◽  
Jamal Talib M Al Roubaie

In this study, the antagonistic effect of five bacteria genera namely Bacillus, Pseudomonas, Azotobacter, Azospirillum, and Streptomyces isolated from rhizosphere of wheat were evaluated against Fusarium graminearum as potential biocontrol agents in vitro. F. graminearum was molecularly diagnosed using the Polymerase chain reaction (PCR) technique. Each bacteria were tested for the production of catalase enzyme, oxidase enzyme, analysis of starch, analyze of gelatin, and the motility, where Azotobacter, Azospirillum, and Bacillus subtilis were positive for all tested. Fungal inhibition tests were performed by using the dual culture method and agar well diffusion technique. Among them, Streptomyces and Azospirillum exhibited potent inhibition to the growth of F. graminearum (72.14% and 66.42%) respectively, followed by B.pumillus, P.fluorescens, B. subtilis and Azotobacter ( 58.28%, 43.23%, 39.71% and 35.71%) respectively as compared with the control treatment (0.0%).The dry weight of the fungus biomass was decreased with bacteria P. fluorescens, Streptomyces sp, Azotobacter sp, Azospirillum sp, B. subtilis, and B. pumillus which reached (0.114, 0.103, 0.147, 0.101, 0.143, and 0.107 g) respectively compared to the control treatment that was 0. 665 g.


2020 ◽  
Author(s):  
N. L. Knight ◽  
B. Macdonald ◽  
C. Percy ◽  
M. W. Sutherland

AbstractHexaploid spring wheat (Triticum aestivum) may exhibit significant crown rot disease responses to infection by Fusarium pseudograminearum, with a range of susceptibility levels available in commercial cultivars. Dry conditions during grain-fill may lead to the expression of prematurely senescing culms, which typically fail to set grain. Assessment of hexaploid spring wheat plants exhibiting both non-senescent and prematurely senescent culms was performed using visual discolouration, Fusarium pseudograminearum biomass, vascular colonisation and quantification of wheat DNA in culm sections sampled at three different heights above the crown and at the peduncle. A comparison of these parameters at four time points from milk development, when senescent culms are first observed, to maturity was conducted. Samples from six commercial cultivars were collected in 2014 from Narrabri and Tamworth, New South Wales and Wellcamp, Queensland. Prematurely senescent culms exhibited greater visual discolouration, Fusarium pseudograminearum biomass and vascular colonisation than non-senescent culms in each cultivar. Colonisation of xylem and phloem tissue was extensive in the basal portions of prematurely senescent culms (36 to 99%), and suggests significant impacts on water and nutrient movement during crown rot disease. Maturation coincided with significant changes in Fusarium pseudograminearum biomass and vascular colonisation. Wheat DNA content varied among cultivars, culm conditions, culm sections and sampling times. The variation in the severity of disease states between culms of the same plant suggests that the timing of initiation of infection in individual culms may vary.


2012 ◽  
Vol 160 (7-8) ◽  
pp. 412-417 ◽  
Author(s):  
Yaxi Liu ◽  
Jun Ma ◽  
Wei Yan ◽  
Guijun Yan ◽  
Meixue Zhou ◽  
...  

1990 ◽  
Vol 38 (3B) ◽  
pp. 407-422
Author(s):  
A. Steg ◽  
S.F. Spoelstra ◽  
J.M. van der Meer ◽  
V.A. Hindle

A total of 50 grass silages were tested in digestibility trials using Texel wethers. The feed silages were wilted of varying DM contents and treated with cell-wall degrading enzymes. The accuracy of feed evaluation was studied using laboratory analyses, including cell-wall analyses, incubation in vitro with rumen fluid and the enzymic procedure. A comparison was made between these results and the current and recently suggested procedures for prediction of digestibility of grass silage. (Abstract retrieved from CAB Abstracts by CABI’s permission)


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