Ricerc@Sapienza

Aphids are among the most destructive pests in agriculture, causing direct damage to crops by feeding on phloem, as well as indirect losses by transmitting more than half of all described plant viruses. During feeding aphids secrete effector proteins into their hosts to manipulate cellular processes and promote infestation. Aphids are largely controlled by pesticides that are environmentally damaging and are being withdrawn from the market. The development of insect-resistant crops represents a viable alternative for aphid control and can be greatly enhanced by knowledge on plant resistance mechanisms against these pests. Cell wall and cell wall-derived oligogalacturonides (OGs), a well-known class of damage-associated molecular patterns (DAMPs), are important components of the plant immune system against fungal and bacterial pathogens, but their role against aphids is unknown. We show that OGs enhance Arabidopsis thaliana resistance to the green peach aphid Myzus persicae. This resistance response is mediated by calcium-dependent protein kinases. Intriguingly, the aphid effector Mp10 suppresses the OG-induced immunity. A. thaliana transgenic plants with increased methyl esterification level of cell wall pectin are more susceptible to aphid colonisation. Our work shows that cell walls and OGs are components of the plant immune response to aphids. This is important, because aphids are likely to release these DAMPs when they penetrate plant cell walls with their stylets. Authors