Effect of mycoviruses on growth, spore germination and pathogenicity of the fungus Fusarium circinatum

Abstract

Aim of the study: To assess the impact on two mycoviruses recently described in F. circinatum mitovirus 1, and 2-2 (FcMV1 and FcMV2-2) on i) mycelial growth, ii) spore germination and iii) relative necrosis.

Material and methods: Fourteen monosporic strains of F. circinatum (one of each pair infected with mycoviruses and the other without them) of the pathogen with and without viruses were selected for the assay. The statistical analysis, were a linear mixed model of analysis of variance considering one between-subjects factor (isolate) and one within-subjects factor with four levels (1=without viruses, 2=only virus FcMV1, 3=only virus FcMV2-2 and 4=both viruses).

Main results: Colony growth rates of F. circinatum isolates were significantly reduced in presence of mycoviruses (p=0.002). The spore germination was also reduced in the F. circinatum isolates containing mycovirus as compared to mycovirus-free isolates (p<0.001). No significant differences in lesion lengths caused by F. circinatum were found in relation to the presence/absence of mycovirus (p<0.61).

Research highlights: Reduction of the percentage of spore germination in the isolates of F. circinatum with mycovirus infections, as compared to free isolates, provides indications of reduction of metabolic activity and plant physiology are discussed. The lack of significant differences found in the length of the lesions caused by F. circinatum with respect to the presence/absence of mycovirus, indicates that further studies with a larger number of variables are required.