Plant resistance to pathogens is commonly associated with a hypersensitive response (HR), but the degree to which the HR is responsible for incompatibility is subject to debate. Resistance to aphids is likely to share features with resistance to pathogens but is less well understood. Here, we report effective resistance to the pea aphid Acyrthosiphon pisum in Medicago truncatula. Aphids lost weight and died rapidly (within two days) on the resistant genotype Jemalong, which developed necrotic lesions following infestation. Lesions were induced by nonvascular intracellular stylet punctures by aphids, remained localized to the site of stylet entry, stained for the presence of reactive oxygen species, and were similar to the HR induced by the bacterial pathogen Pseudomonas syringae pv. phaseolicola. The implication that aphid-induced lesions confer resistance was tested by quantitative trait loci analysis using recombinant inbred lines derived from a cross between Jemalong and the susceptible genotype DZA315.16. One major locus, RAP1, was identified that was sufficient to confer race-specific resistance against the pea aphid and was mapped to the middle of chromosome 3. Surprisingly, a separate locus, mapping to the top of chromosome 3, governed aphid-induced HR, indicating that the HR-like lesions are not required for RAP1-mediated aphid resistance.

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Household dust contains an array of constituents, including house dust mites (HDM) and the HDM allergen, Der p 1, which can cause sensitivities such as asthma and eczema. Vacuuming can help alleviate symptoms, yet little is understood about cleaning behaviour in different households. This pilot study investigated the contents of dust from four household types (students; over 65 s; and families with and without pets). This was then related to cleaning behaviours and perceptions of cleanliness. Our investigation found that HDMs and Der p 1 were present in all households and sampling locations, including participants' cars. The median Der p 1 was greatest in the living room, though results varied. Demographic group was a determinant for the number of human and pet hairs present in dust. Surprisingly, vacuuming was the most disliked task overall. This information requires consideration when developing cleaning products and advising individuals with dust-related health issues.