Journal of Chemical Ecology (2021) 47, 112-122

Joana Carvalho Cachapa, Nicolai Vitt Meyling, Meike Burow and Thure Pavlo Hauser (2021)
Induction and priming of plant defense by root-associated insect-pathogenic fungi
Journal of Chemical Ecology 47 (1), 112-122
Abstract: Plants evolved in close contact with a myriad of microorganisms, some of which formed associations with their roots, benefitting from carbohydrates and other plant resources. In exchange, they evolved to influence important plant functions, e.g. defense against insect herbivores and other antagonists. Here, we test whether a fungus, Metarhizium brunneum, which is mostly known as an insect pathogen, can also associate with plant roots and contribute to above-ground plant defense. Cauliflower (Brassica oleracea var. botrytis) seeds were sown together with M. brunneum-inoculated rice grains, and the resulting plants subjected to leaf herbivory by the specialist Plutella xylostella. Activity of myrosinases, the enzymes activating glucosinolates, was measured before and after herbivory; larval consumption and plant weight at the end of experiments. Metarhizium brunneum clearly established in the plant roots, and after herbivory myrosinase activity was substantially higher in M. brunneum-treated plants than in controls; before herbivory, M. brunneum-treated and control plants did not differ. Leaf consumption was slightly lower in the M. brunneum-treated plants whereas total biomass and allocation to above- or below-ground parts was not affected by the Metarhizium treatment. Thus, M. brunneum associates with roots and primes the plant for a stronger or faster increase in myrosinase activity upon herbivory. Consistent with this, myrosinase function has been suggested to be rate-limiting for induction of the glucosinolate-myrosinase defense system. Our results show that M. brunneum, in addition to being an insect pathogen, can associate with plant roots and prime plant defense.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Nicolai Vitt Meyling

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
resistance/tolerance/defence of host
Research topic(s) for beneficials or antagonists:
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Plutella xylostella	Cabbage (Brassica oleracea)
Metarhizium brunneum (entomopathogen)	Plutella xylostella	Cabbage (Brassica oleracea)