AUTHOR=Li Bo , Cao Yuhan , Ji Zixuan , Zhang Jingyi , Meng Xianglong , Dai Pengbo , Hu Tongle , Wang Shutong , Cao Keqiang , Wang Yanan 

TITLE=Coinfection of Two Mycoviruses Confers Hypovirulence and Reduces the Production of Mycotoxin Alternariol in Alternaria alternata f. sp. mali

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.910712

DOI=10.3389/fmicb.2022.910712

ISSN=1664-302X

ABSTRACT=<p><italic>Alternaria</italic> leaf blotch caused by <italic>Alternaria alternata</italic> apple pathotype (<italic>Alternaria mali</italic>) is an important fungal disease that affects the production of apples worldwide. Mycoviruses harbored in plant pathogenic fungi can confer hypovirulence in their hosts and have attracted widespread attention as potential biocontrol tools. In this study, the coinfection of two mycoviruses, named <italic>A. alternata</italic> chrysovirus 1 strain QY2 (AaCV1-QY2) and <italic>A. alternata</italic> magoulivirus 1 (AaMV1), respectively, were isolated from <italic>A. alternata</italic> f. sp. <italic>mali</italic> strain QY21. Sequence analyses revealed that AaCV1-QY2 virus belonged to the genus <italic>Betachrysovirus</italic> and AaMV1 virus belonged to the genus <italic>Magoulvirus.</italic> These two mycoviruses were found to be associated with hypovirulence in <italic>A. alternata</italic>, among which AaCV1-QY2 might play a relatively leading role. Because the elimination of AaMV1 from the strain QY21 does not affect the hypovirulence trait, which indicates that the virus AaCV1-QY2 can independently induce slow growth and reduce host virulence. Moreover, the presence of viruses decreased the accumulation of the mycotoxin alternariol (AOH) in <italic>A. alternata</italic> strains. Intriguingly, AaCV1-QY2/AaMV1 mycoviruses can be horizontally transmitted to other <italic>A. alternata</italic> strains, and this coinfection can promote the interspecific transmission efficiency of AaCV1-QY2. To our knowledge, this study reports the first description of the member of <italic>Chrysovirus</italic> is related to hypovirulence in <italic>Alternaria</italic> spp. that facilitates the development of biocontrol measures of <italic>A. mali</italic> Roberts.</p>