Profiling of differentially expressed genes in ectomycorrhizal fungus Pisolithus tinctorius responding to mycorrhiza helper Brevibacillus reuszeri MPt17

A cDNA library of the ectomycorrhizal (ECM) fungus Pisolithus tinctorius Pt2 after interaction with the mycorrhiza helper bacterium (MHB) Brevibacillus reuszeri MPt17 was constructed by suppression subtraction hybridization. Total RNA from B. reuszeri MPt17 exudates treated Pi. tinctorius Pt2 was used as a “tester” and total RNA from nonbacterial treated Pi. tinctorius Pt2 was used as a “driver.” Among the differentially expressed sequences, a BLASTX in the NCBI non-redundant protein sequence database revealed that 75% of the non-redundant sequences (147 out of 196) were highly similar to known proteins (E-value < e−5). Twelve sequences were annotated as mycelium development function combining with a potential functional categories using gene ontology. Quantitative real-time PCR analysis showed that all of the 3 symbiosis regulated acidic polypeptide genes were all up-regulated in the MPt17-treated Pt2. These results provide evidence that the MHB B. reuszeri MPt17 could significantly change the expression of symbiosis-related genes and genes in mycelium development in ECM fungus, and also support the hypothesis that the MHB functions as helper though promotion on fungal mycelium.