Gene expression associated with vegetative incompatibility in Amylostereum areolatum

Abstract

In filamentous fungi, vegetative compatibility among individuals of the same species is determined by the genes encoded at the heterokaryon incompatibility (het) loci. The hyphae of genetically similar individuals that share the same allelic specificities at their het loci are able to fuse and intermingle, while different allelic specificities at the het loci result in cell death of the interacting hyphae. In this study, suppression subtractive hybridization (SSH) followed by pyrosequencing and quantitative reverse transcription PCR were used to identify genes that are selectively expressed when vegetatively incompatible individuals of Amylostereum areolatum interact. The SSH library contained genes associated with various cellular processes, including cell-cell adhesion, stress and defence responses, as well as cell death. Some of the transcripts encoded proteins that were previously implicated in the stress and defence responses associated with vegetative incompatibility. Other transcripts encoded proteins known to be associated with programmed cell death, but have not previously been linked with vegetative incompatibility.Results of this study have considerably increased our knowledge of the processes underlying vegetative incompatibility in Basidiomycetes in general and A. areolatum in particular.

A 2nd Generation Linkage Map of Heterobasidion annosum s.l. Based on In Silico Anchoring of AFLP Markers

“…Specific primers for all 39 genes were designed using Primer3. Alleles were distinguished in the parental genomes TC-122-12 and TC-32-1 using PCR-RFLP (restriction fragment length polymorphism) [42] analysis (50 cycles, denaturation (30 s, 95°C), annealing (30 s, 60°C), extension (30 s, 72°C)) and agarose gel electrophoresis. The genes were mapped by scoring allele segregation in the mapping population [27] using the EvaGreen dye (Biotium Inc., Hayward, CA, USA) together with post-PCR DNA High Resolution Melting curve analysis [43].…”

The Transcriptional Response to Nonself in the FungusPodospora anserina

“…Transcriptional changes were extensive with more than 3000 genes showing a differential expression, with roughly similar numbers of these being up-regulated and down-regulated genes. Gene expression changes were also analyzed by subtractive hybridization in the filamentous basidiomycete Amylostereum areolatum (van der Nest et al 2011). To gain a global picture of the expression changes occurring during incompatibility in Podospora , we performed a genome wide transcriptional profiling in the het-R het-V SI strain upon the induction of the incompatibility reaction.…”

Somatic incompatibility and genetic structure of fungal crops in sympatric Atta colombica and Acromyrmex echinatior leaf-cutting ants

“…To make further progress, it would be desirable to identify the genes that are directly responsible for somatic incompatibility, as this would allow direct studies on the signatures of selection and specialization across the clades of higher attine ant symbionts. In another, non-eusocial model system of fungus-growing insects, the Sirex wood wasp, a range of genes are involved in somatic incompatibility reactions among lineages of the associated fungus, including fusion and recognition genes and genes that mediate cellular damage, stress response, and programmed cell death ( Van der Nest et al., 2011 ). Whether these genes have homologs or analogs in attine ant fungal symbionts remains to be explored, as the Sirex symbiont Amylostereum areolatum belongs to a distantly related clade of basidiomycetes ( Binder and Hibbett, 2002 ), and their respective domestication histories may have implied that recognition systems were lost and gained over evolutionary time.…”

“…These reactions tend to be stepwise ( Rayner et al., 1984 , Rayner, 1991 , Worrall, 1997 ) and usually involve dark pigmentation in the interaction zone ( Rayner et al., 1984 ), changes in septal maintenance, or blockage of septa precluding the movement of cytoplasm, and can lead to programmed cell death ( Rayner, 1991 ). The underlying genetic mechanisms remain largely unknown, but multiple loci appear to be involved ( Worrall, 1997 ) and their expression may be linked to sexual incompatibility genes ( Van der Nest et al., 2009 , Van der Nest et al., 2011 ). If sex occurs at all, it is extremely rare in the fungal symbionts of higher attine ants ( Fisher et al., 1994a , Fisher et al., 1994b , Pagnocca et al., 2001 , Mueller, 2002 , Mikheyev et al., 2006 ).…”