Diversity of dsRNA mycoviruses in Magnaporthe oryzae and correlation relationship of the mycoviruses and biological characters of their host strain QSP5
Abstract:Mycoviruses are widespread in filamentous fungi and yeast; some of them are related to impaired growth, abnormal sporulation and pigmentation of their hosts. In this study, 120 M. oryzae isolates were obtained from rice blast lesions on leaves by using single-conidium isolation technique, and about 52% of these isolates contained dsRNA fragments. One of these strains QSP5 is infected by two mycoviruses, namely M. oryzae chrysovirus 1-C (MoCV1-C) and M. oryzae virus 3 (MoV3) according to their high similarity to M. oryzae chrysovirus 1-A (MoCV1-A) and M. oryzae virus 2 (MoV2). Besides, a single-conidium isolate QSP5-9, only infected by MoV3, was obtained from the conidia of strain QSP5. Comparative analysis of sporulation production, mycelial and colonial morphology between QSP5 and QSP5-9 revealed that MoCV1-C may be mainly rela-ted to abnormal sporulation, mycelial growth and pigmentation. Meanwhile, to test the stability of MoV3 in M. oryzae, 100 single-conidium isolates of M. oryzae strain QSP5 were obtained and MoV3 was detected in all the 40 randomly selected isolates, however, MoCV1-C only existed in part of these isolates. In addition, 94 single-conidium isolates of M. oryzae strain QSP5-9 were obtained and 45 randomly selected isolates were proved to carry the same dsRNA genome as strain QSP5-9. These results indicated that MoV3 is stable in M. oryzae.