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A novel virus that infecting hypovirulent strain XG36-1 of plant fungal pathogen Sclerotinia sclerotiorum.

Zhang L, Fu Y, Xie J, Jiang D, Li G, Yi X - Virol. J. (2009)

Bottom Line: Hypovirulence is a phenomenon where the virulence of fungal pathogens is decreased, even lost, due to mycovirus infection.Furthermore, the viral particles could be co-transmitted with the hypovirulence traits through hyphal anastomosis.Currently, we could not know the characteristic of this virus, but it likely represent a new type of mycovirus in S. sclerotiorum, and possibly in fungi.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, Hubei Province, PR China. zhangliyan@webmail.hzau.edu.cn

ABSTRACT

Background: Sclerotinia sclerotiorum is a notorious plant fungal pathogen which spreads across the world. Hypovirulence is a phenomenon where the virulence of fungal pathogens is decreased, even lost, due to mycovirus infection. The potential of hypoviruses for biological control of the chestnut blight fungus (Cryphonectria parasitica) has attracted much interest, and has led to discovery of new hypovirulent strains in other fungi.

Results: A hypovirulent strain, strain XG36-1, was isolated from a typical lesion on the stem of rapeseed (Brassica napus) caused by Sclerotinia sclerotiorum. Strain XG36-1 grew on PDA very slowly (average 2.5 +/- 0.1 mm/d) with sectoring, and developed abnormal colony morphology with few sclerotia. Unlike health strains (such as wildtype strain XG-13), it was unable to induce lesions on detached leaves of rapeseed. Sclerotia of strain XG36-1 produced apothecia rarely. A sexual progeny test showed that the phenotypes of all 104 sexual progeny were not different from wildtype strain XG-13 which shows normal phenotype of S. sclerotiorum, and protoplast regeneration tests showed that 25.5% of the regenerants of strain XG36-1 were recovered fully. Furthermore, the hypovirulence and its associated traits could be transmitted to XG36-1A34R, a hygromycin-resistance gene labelled sexual progeny of strain XG36-1, by hyphal anastomosis. Transmission electron microscope (TEM) observation showed that the cytoplasm of strain XG36-1 was destroyed and granulated; the membranes of nuclei and mitochondria were disintegrated; and mitochondrial cristae were cavitated. Viral particles (about 40 nm) in hyphae of strain XG36-1, but not in its sexual progeny and wildtype strain XG-13, could be observed with TEM, and several virus-like particles were uniquely enveloped by single layer membrane in the cells of strain XG36-1. Furthermore, the viral particles could be co-transmitted with the hypovirulence traits through hyphal anastomosis.

Conclusion: Hypovirulence and its associated traits of strain XG36-1 could be mediated by a fungal virus. Currently, we could not know the characteristic of this virus, but it likely represent a new type of mycovirus in S. sclerotiorum, and possibly in fungi.

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Sexual progeny of hypovirulent strain XG36-1 showed normal phenotypes of S. sclerotiorum. A and B, the colony morphology and virulence on rapeseed detached leaves of a randomly selected sexual progeny XG36-1A34; C, the growth rate of 104 tested sexual progeny.
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Figure 3: Sexual progeny of hypovirulent strain XG36-1 showed normal phenotypes of S. sclerotiorum. A and B, the colony morphology and virulence on rapeseed detached leaves of a randomly selected sexual progeny XG36-1A34; C, the growth rate of 104 tested sexual progeny.

Mentions: Only a few of sclerotia of strain XG36-1 could be successfully induced to form apothecia. 104 single-ascospore-isolation sexual progeny were obtained. The cultural characteristics and pathogenicity of these 104 sexual progeny were tested, and the results showed that all sexual progeny had a typical wildtype phenotype of S. sclerotiorum. Compared to strain XG-13, the grow rate, colony morphology of sexual progeny were not significantly different (Fig 3).


A novel virus that infecting hypovirulent strain XG36-1 of plant fungal pathogen Sclerotinia sclerotiorum.

Zhang L, Fu Y, Xie J, Jiang D, Li G, Yi X - Virol. J. (2009)

Sexual progeny of hypovirulent strain XG36-1 showed normal phenotypes of S. sclerotiorum. A and B, the colony morphology and virulence on rapeseed detached leaves of a randomly selected sexual progeny XG36-1A34; C, the growth rate of 104 tested sexual progeny.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2714488&req=5

Figure 3: Sexual progeny of hypovirulent strain XG36-1 showed normal phenotypes of S. sclerotiorum. A and B, the colony morphology and virulence on rapeseed detached leaves of a randomly selected sexual progeny XG36-1A34; C, the growth rate of 104 tested sexual progeny.
Mentions: Only a few of sclerotia of strain XG36-1 could be successfully induced to form apothecia. 104 single-ascospore-isolation sexual progeny were obtained. The cultural characteristics and pathogenicity of these 104 sexual progeny were tested, and the results showed that all sexual progeny had a typical wildtype phenotype of S. sclerotiorum. Compared to strain XG-13, the grow rate, colony morphology of sexual progeny were not significantly different (Fig 3).

Bottom Line: Hypovirulence is a phenomenon where the virulence of fungal pathogens is decreased, even lost, due to mycovirus infection.Furthermore, the viral particles could be co-transmitted with the hypovirulence traits through hyphal anastomosis.Currently, we could not know the characteristic of this virus, but it likely represent a new type of mycovirus in S. sclerotiorum, and possibly in fungi.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, Hubei Province, PR China. zhangliyan@webmail.hzau.edu.cn

ABSTRACT

Background: Sclerotinia sclerotiorum is a notorious plant fungal pathogen which spreads across the world. Hypovirulence is a phenomenon where the virulence of fungal pathogens is decreased, even lost, due to mycovirus infection. The potential of hypoviruses for biological control of the chestnut blight fungus (Cryphonectria parasitica) has attracted much interest, and has led to discovery of new hypovirulent strains in other fungi.

Results: A hypovirulent strain, strain XG36-1, was isolated from a typical lesion on the stem of rapeseed (Brassica napus) caused by Sclerotinia sclerotiorum. Strain XG36-1 grew on PDA very slowly (average 2.5 +/- 0.1 mm/d) with sectoring, and developed abnormal colony morphology with few sclerotia. Unlike health strains (such as wildtype strain XG-13), it was unable to induce lesions on detached leaves of rapeseed. Sclerotia of strain XG36-1 produced apothecia rarely. A sexual progeny test showed that the phenotypes of all 104 sexual progeny were not different from wildtype strain XG-13 which shows normal phenotype of S. sclerotiorum, and protoplast regeneration tests showed that 25.5% of the regenerants of strain XG36-1 were recovered fully. Furthermore, the hypovirulence and its associated traits could be transmitted to XG36-1A34R, a hygromycin-resistance gene labelled sexual progeny of strain XG36-1, by hyphal anastomosis. Transmission electron microscope (TEM) observation showed that the cytoplasm of strain XG36-1 was destroyed and granulated; the membranes of nuclei and mitochondria were disintegrated; and mitochondrial cristae were cavitated. Viral particles (about 40 nm) in hyphae of strain XG36-1, but not in its sexual progeny and wildtype strain XG-13, could be observed with TEM, and several virus-like particles were uniquely enveloped by single layer membrane in the cells of strain XG36-1. Furthermore, the viral particles could be co-transmitted with the hypovirulence traits through hyphal anastomosis.

Conclusion: Hypovirulence and its associated traits of strain XG36-1 could be mediated by a fungal virus. Currently, we could not know the characteristic of this virus, but it likely represent a new type of mycovirus in S. sclerotiorum, and possibly in fungi.

Show MeSH
Related in: MedlinePlus