Fig. 3
The set of differentially expressed genes of M. persicae clone O reared on B. rapa and N. benthamiana is enriched for (a) genes belonging to gene families with known functions, (b) tandemly duplicated genes in the M. persicae genome, (c) genes belonging to gene families expanded in aphids or unique to aphids, (d) duplicated genes before M. persicae and A. pisum diverged and (e) genes with stronger purifying selection than the genome-wide average. a–c Volcano plots of differentially expressed genes of M. persicae reared on B. rapa and N. benthamiana. Negative log2 fold changes indicate upregulation on B. rapa and positive values indicate upregulation on N. benthamiana. a Differentially expressed genes from four gene families that have the highest number of differentially expressed genes are highlighted. These are: RR-2 cuticular proteins (n = 22), cathepsin B (n = 10), UDP-glucosyltransferase (n = 8) and cytochrome P450 (n = 5). b The set of differentially expressed genes is enriched for tandemly duplicated genes. c The set of differentially expressed genes is enriched for genes from families that are either significantly expanded in aphids compared to other arthropods (binomial test, main text) or are unique to aphids. d Time since most recent duplication (measured as d S ) for all paralogs in the M. persicae genome compared to those differentially expressed upon host transfer. Duplicated genes implicated in host adjustment (at least one of the pair differentially expressed) have a significantly different distribution to the genome wide average (p < 0.05, permutation test of equality) and are enriched for genes that duplicated before M. persicae and A. pisum diverged. e d N /d S distribution for duplicated genes differentially expressed upon host transfer vs. the genome wide average. Duplicated genes involved in host adjustment are under significantly stronger purifying selection than the genome wide average (median d N /d S  = 0.2618 vs. 0.3338, Mann–Whitney U = 105,470, p = 1.47 × 10−4, two-tailed)