3 research outputs found
Evidence of the Biochemical Basis of Host Virulence in the Greenbug Aphid, <i>Schizaphis graminum</i> (Homoptera: Aphididae)
Biotypes
of aphids and many other insect pests are defined based
on the phenotypic response of host plants to the insect pest without
considering their intrinsic characteristics and genotypes. Plant breeders
have spent considerable effort developing aphid-resistant, small-grain
varieties to limit insecticide control of the greenbug, <i>Schizaphis
graminum</i>. However, new <i>S. graminum</i> biotypes
frequently emerge that break resistance. Mechanisms of virulence on
the aphid side of the plant–insect interaction are not well
understood. <i>S. graminum</i> biotype H is highly virulent
on most small grain varieties. This characteristic makes biotype H
ideal for comparative proteomics to investigate the basis of biotype
virulence in aphids. In this study, we used comparative proteomics
to identify protein expression differences associated with virulence.
Aphid proteins involved in the tricarboxylic acid cycle, immune system,
cell division, and antiapoptosis pathways were found to be up-regulated
in biotype H relative to other biotypes. Proteins from the bacterial
endosymbiont of aphids were also differentially expressed in biotype
H. Guided by the proteome results, we tested whether biotype H had
a fitness advantage compared with other <i>S. graminum</i> biotypes and found that biotype H had a higher reproductive fitness
as compared with two other biotypes on a range of different wheat
germplasms. Finally, we tested whether aphid genetics can be used
to further dissect the genetic mechanisms of biotype virulence in
aphids. The genetic data showed that sexual reproduction is a source
of biotypic variation observed in <i>S. graminum.</i