Studies on the virome of the entomopathogenic fungus Beauveria bassiana reveal novel dsRNA elements and mild hypervirulence.

© 2017 Kotta-Loizou, Coutts. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Kotta-Loizou I, Coutts RHA (2017) 'Studies on the Virome of the Entomopathogenic Fungus Beauveria bassiana Reveal Novel dsRNA Elements and Mild Hypervirulence', PLoS Pathogens, 13(1): e1006183. doi:10.1371/journal.ppat.1006183The entomopathogenic fungus Beauveria bassiana has a wide host range and is used as a biocontrol agent against arthropod pests. Mycoviruses have been described in phytopathogenic fungi while in entomopathogenic fungi their presence has been reported only rarely. Here we show that 21.3% of a collection of B. bassiana isolates sourced from worldwide locations, harbor dsRNA elements. Molecular characterization of these elements revealed the prevalence of mycoviruses belonging to the Partitiviridae and Totiviridae families, the smallest reported virus to date, belonging to the family Narnaviridae, and viruses unassigned to a family or genus. Of particular importance is the discovery of members of a newly proposed family Polymycoviridae in B. bassiana. Polymycoviruses, previously designated as tetramycoviruses, consist of four non-conventionally encapsidated capped dsRNAs. The presence of additional non-homologous genomic segments in B. bassiana polymycoviruses and other fungi illustrates the unprecedented dynamic nature of the viral genome. Finally, a comparison of virus-free and virus-infected isogenic lines derived from an exemplar B. bassiana isolate revealed a mild hypervirulent effect of mycoviruses on the growth of their host isolate and on its pathogenicity against the greater wax moth Galleria mellonella, highlighting for the first time the potential of mycoviruses as enhancers of biocontrol agents.Peer reviewedFinal Published versio

Differential expression of heat shock protein genes in sorghum (Sorghum bicolor L.) genotypes under heat stress

Abstract Various types of sorghum were subjected to thermal stress to reveal the mode of expression of genes of the heat shock protein (hsp) family. In silico sequence determination of hsp genes in related cereal species led to the selection of appropriate primers for PCR amplification of a segment corresponding to the hsp90 gene from sorghum. Deduced sequence information allowed the design of gene specific primers for quantification of hsp90 gene expression by means of real-time quantitative polymerase chain reaction (RTqPCR). Fourteen days-old plants were exposed to a temperature of 47°C for a time period ranging from 10 to 180 min. Total RNA was extracted from stressed and control plants and subjected to reverse transcription and RT-qPCR analysis. The actin gene was used as an internal standard. Gene expression was assessed by using cDNA from all types of plant material and for all the different durations of heat stress exposure. Data from RT-qPCR analyses were analyzed using REST software. The highest level of hsp90 gene expression was realized upon exposure to heat for either 60 or 30 min, while expression levels differed among the genotypes studied. In addition, overall levels of hsp90 gene expression were significantly different among varieties tested. Information of such genotypic variation in expression levels of hsp90 gene under heat stress, coupled with related field performance data, could potentially be exploited in breeding programs