Molecular and chemical mechanisms involved in aphid resistance in cultivated tomato

P>An integrated approach has been used to obtain an understanding of the molecular and chemical mechanisms underlying resistance to aphids in cherry-like tomato (Solanum lycopersicum) landraces from the Campania region (southern Italy). The aphid-parasitoid system Macrosiphum euphorbiae-Aphidius ervi was used to describe the levels of resistance against aphids in two tomato accessions (AN5, AN7) exhibiting high yield and quality traits and lacking the tomato Mi gene. Aphid development and reproduction, flight response by the aphid parasitoid A. ervi, gas chromatography-mass spectrometry headspace analysis of plant volatile organic compounds and transcriptional analysis of aphid responsive genes were performed on selected tomato accessions and on a susceptible commercial variety (M82). When compared with the cultivated variety, M82, AN5 and AN7 showed a significant reduction of M. euphorbiae fitness, the release of larger amounts of specific volatile organic compounds that are attractive to the aphid parasitoid A. ervi, a constitutively higher level of expression of plant defence genes and differential enhancement of plant indirect resistance induced by aphid feeding. These results provide new insights on how local selection can offer the possibility of the development of innovative genetic strategies to increase tomato resistance against aphids.