Comparison of potato aphid isolates, Macrosiphum euphorbiae, with variable responses to host plant resistance in tomato, Solanum lycopersicum

The Mi gene in tomato confers resistance against certain biotypes of phloem feeders including the potato aphid, M. euphorbiae. Resistance reduces fecundity, survival and feeding in the aphids. Different potato aphid populations can vary widely in their virulence, or their ability to colonize resistant plants. For example, Mi-mediated resistance causes ~95% reduction in the population growth of one avirulent potato aphid clone (isolate WU11), but only a 15% reduction in the semi-virulent WU12 isolate. The objective of this project is to investigate why these aphid isolates respond variably to the Mi resistance in tomato. The methods we have utilized include electronic monitoring of aphid feeding behavior on resistant and susceptible plants, as well as 2D DIGE analysis of WU11 and WU12 protein profiles when exposed to resistant and susceptible hosts. In addition, we have explored differences in plant transcriptional responses to the avirulent and semi-virulent aphid isolates using real-time RT-PCR. Our results and their implications for gene-for-gene interactions between plants and aphids will be discussed.