Mycorrhiza induced resistance in potato plantlets challenged by Phytophthora infestans

Biological control of soil-borne pathogens by arbuscular mycorrhizal (AM) fungi has been repeatedly demonstrated. However, their role in the control of above-ground hemibiotrophic pathogens is less conclusive. Here, we investigated in vitro the impact of an AM fungus on Phytophthora infestans in potato plants. The leaf infection index was decreased in mycorrhizal potato plants. Real-Time Quantitative PCR revealed the induction of two pathogenesis related genes (PR1 and PR2) in the leaves of mycorrhizal plants shortly after infection with P. infestans. These results suggested a systemic resistance in mycorrhizal plants, related to the priming of the two PR genes in potato.

► AM fungi as bio-control agent against P. infestans infection on potato leaves.
► AM fungi promote a decrease of leaves symptoms caused by P. infestans.
► P. infestans do not influence the AM fungal root colonization.
► Decrease of symptoms was related to induction of PR1 and PR2 genes in leaves.
► Systemic resistance triggered by AM fungi was presumably related to the priming of the two PR genes.