Potentiation of Mycovirus Transmission by Zinc Compounds via Attenuation of Heterogenic Incompatibility in Rosellinia necatrix

Abstract

cHeterogenic incompatibility is considered a defense mechanism against deleterious intruders such as mycovirus. Rosellinia necatrix shows strong heterogenic incompatibility. In the heterogenic incompatibility reaction, the approaching hyphae hardly anastomosed, a distinctive barrage line formed, and green fluorescent protein (GFP)-labeled hyphae quickly lost their fluorescence when encountering incompatible hyphae. In this study, transmission of a hypovirulence-conferring mycovirus to strains with different genetic backgrounds was attempted. Various chemical reagents considered to affect the programmed cell death pathway or cell wall modification were examined. Treatment with zinc compounds was shown to aid in transmission of mycoviruses to strains with different genetic backgrounds. In incompatible pairings, treatment with zinc compounds accelerated hyphal anastomosis; moreover, cytosolic GFP was transmitted to the newly joined hyphae. These results suggest that zinc compounds not only increase hyphal anastomosis but also attenuate heterogenic incompatibility.

Virus-mediated suppression of host non-self recognition facilitates horizontal transmission of heterologous viruses

“…Second, the vegetative incompatibility reaction could be attenuated by amending the growth medium with certain chemicals, e.g., zinc chloride treatment was found to suppress vegetative incompatibility reaction in R . necatrix and to benefit mycovirus horizontal transmission [61]. Third, disruption of vic genes resulted in enhancing mycovirus transmission.…”

Vertical Transmission of Fusarium circinatum Mitoviruses FcMV1 and FcMV2-2 via Microconidia

“…Other studies have indicated that in vitro assays may underestimate the transmission of viruses, especially horizontal transmission, and their ability to overcome the barrier of fungal somatic incompatibility [48,59]. Lee et al [60] showed that it was possible to transmit viruses between different species in the laboratory via protoplast fusion, whereas Ikeda et al [61] demonstrated that zinc chloride treatment helped the transmission of the mycovirus because it inhibited heterogenic incompatibility in R. necatrix. In the Spanish population of F. circinatum, natural transmission between other species was studied by isolating other fungi in which the disease is commonly established, although no virus was detected in any other fungal species [62].…”

50-plus years of fungal viruses

“…In addition, conidia of R. necatrix scarcely germinate to generate mycelia under laboratory conditions. A strong point of R. necatrix, on the other hand, is applicability of a zinc-mediated method for horizontal transmission of viruses between mycelially incompatible strains (Ikeda et al, 2013), which is worth testing in other filamentous fungi.…”