Differential gene expression during interactions betweenHeterobasidion annosumandPhysisporinus sanguinolentus

Abstract

Using mRNA differential display we have identified differentially expressed genes in non-self-interacting vs. single mycelia of the conifer pathogen Heterobasidion annosum and the wood decomposing basidiomycete Physisporinus sanguinolentus. Altogether 39 differentially displayed bands were cloned and sequenced, corresponding to 21 unique genes, which were confirmed by semi-quantitative RT-PCR to be differentially expressed. Further confirmation of differential gene expression was made by real time RT-PCR. All 10 genes identified from P. sanguinolentus had lower expression, while in H. annosum three genes had higher and eight lower expression in non-self-interacting mycelia vs. single mycelia. One of the induced genes showed high similarity to the Coprinus cinereus recA/RAD51 homolog (rah1) which is essential for homologous recombination, DNA repair and stress responses.

Differential Gene Expression in Pycnoporus coccineus during Interspecific Mycelial Interactions with Different Competitors

“…In the case of the interaction between P. coccineus and C. puteana, our data are convergent with these findings (609 overexpressed and 734 underexpressed), but for the interaction with B. cinerea, our results are divergent, with the number of underexpressed transcripts almost 7 times higher than the number of overexpressed transcripts. Multiple studies have reported that interspecific fungal interactions lead to genetic repression (11,(26)(27)(28), but the cause of this regulation is unclear. It is not known whether it is the result of a downregulation by the fungus itself, and therefore a part of its interaction mechanism, or if it is the result of actions of the competitor's effectors (28).…”

“…Current knowledge also indicates that during an interaction, fungi produce and secrete enzymatic effectors, including metalloproteins (12,57) and secondary metabolites (1), in order to interfere with their competitors. Interacting fungi also have to repair the structures damaged during the interaction, such as cell walls (28) or DNA (11). Setting up these attack and defense pathways has a metabolic cost, which is another factor that explains the growth limitation.…”

“…The outcome of these interactions will in turn affect the succession of species, community development, and substratum decay (3-5). This ability to eliminate competitors has also been used as a biotechnological tool, with the development of methods using aggressive, strongly antagonistic species, such as Trichoderma sp., to control plantpathogenic and wood rot fungi (1, 6, 7).When antagonistic relations occur, a broad array of responses can be observed, including changes in mycelial morphology at the interaction front, modification of metabolism, and production and secretion of extracellular enzymes (1,(8)(9)(10)(11). Two main pathways are used to gain an advantage over the competitor: development of attack or defense mechanisms and improvements in nutrient uptake (12).…”

“…When antagonistic relations occur, a broad array of responses can be observed, including changes in mycelial morphology at the interaction front, modification of metabolism, and production and secretion of extracellular enzymes (1,(8)(9)(10)(11). Two main pathways are used to gain an advantage over the competitor: development of attack or defense mechanisms and improvements in nutrient uptake (12).…”

Identification of Differentially Expressed Genes by cDNA-Amplified Fragment Length Polymorphism in the Biocontrol Agent Pichia anomala (Strain Kh5)

“…Differential display is now being applied in the biological control field. It recently allowed the identification of an aspartyl protease from Trichoderma asperellum (45) and genes differentially expressed during nonself fungal-fungal interactions of the decomposing basidiomycete Physisporinus sanguinoletus (22). Compared with differential display, cDNA-amplified fragment length polymorphism (cDNA-AFLP) analysis (5), a nonbiased technique based on PCR amplification, offers the advantage of higher reproducibility (16).…”