The increasing request for alternatives to conventional chemical products against plant pathogens is shifting the research towards biocontrol agents. While great efforts have been made in the case of diseases of agricultural crops, forest diseases have received limited attention. Heterobasidion annosum is a complex of five different fungal species responsible for the most destructive root and/or butt rots of conifers in the northern hemisphere. With the exception of the fungus Phlebiopsis gigantea, there are no microorganisms available to control in practice Heterobasidion spp. This study investigated the effectiveness in vitro of a commercially available strain of Pseudomonas (DSMZ 13134, Proradix®) against the four Heterobasidion spp. present in Europe, including the exotic H. irregulare. The dual culture technique was used to assess the mycelial growth inhibition due to either pathogen-antagonist interaction or to volatile organic compounds (VOCs) produced by Proradix®. The effects of the biocontrol agent on the germination of spores were investigated as well. Experiments were carried out on two culture media at two different temperatures. Proradix® significantly (P<0.05) affected the growth of Heterobasidion spp. as well as spore germination depending on tested conditions and Heterobasidion species. Preliminary results suggested that VOCs do not play a major role in the inhibition of Heterobasidion spp. The adoption of a genomic approach is pivotal to elucidate the mechanisms of action of Proradix® against Heterobasidion spp. Moreover, the potential discovery of new biological compounds could answer the social demand for alternatives to chemical treatments against plant diseases.
Biocontrol potential of Pseudomonas sp. DSMZ 13134 against the fungal forest pathogens Heterobasidion spp.
PELLICCIARO M.;GIORDANO L.;LIONE G.;SILLO F.;GONTHIER P.
2019-01-01
Abstract
The increasing request for alternatives to conventional chemical products against plant pathogens is shifting the research towards biocontrol agents. While great efforts have been made in the case of diseases of agricultural crops, forest diseases have received limited attention. Heterobasidion annosum is a complex of five different fungal species responsible for the most destructive root and/or butt rots of conifers in the northern hemisphere. With the exception of the fungus Phlebiopsis gigantea, there are no microorganisms available to control in practice Heterobasidion spp. This study investigated the effectiveness in vitro of a commercially available strain of Pseudomonas (DSMZ 13134, Proradix®) against the four Heterobasidion spp. present in Europe, including the exotic H. irregulare. The dual culture technique was used to assess the mycelial growth inhibition due to either pathogen-antagonist interaction or to volatile organic compounds (VOCs) produced by Proradix®. The effects of the biocontrol agent on the germination of spores were investigated as well. Experiments were carried out on two culture media at two different temperatures. Proradix® significantly (P<0.05) affected the growth of Heterobasidion spp. as well as spore germination depending on tested conditions and Heterobasidion species. Preliminary results suggested that VOCs do not play a major role in the inhibition of Heterobasidion spp. The adoption of a genomic approach is pivotal to elucidate the mechanisms of action of Proradix® against Heterobasidion spp. Moreover, the potential discovery of new biological compounds could answer the social demand for alternatives to chemical treatments against plant diseases.
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