Reverse genetics has become a particularly popular approach to the genetic analysis of insects because of the widespread applicability of gene silencing technologies like the injection or feeding of dsRNA. While a relatively blunt tool, dsRNA injection has been used with great affect in many insects. Forward genetic approaches tend to be more challenging in ‘non-model’ insects but provide unique opportunities to probe biological processes.
Aphids provide a number of examples of extreme phenotypic plasticity, the genetic bases of which are not known. Tagu et al. have courageously attempted to develop a forward genetic approach to the study of the pea aphid. The pea aphid (Acyrthosiphon pisum) has been selected by aphidologists to be the reference aphid species for which there is a growing number of genomic resources.
Aphids offer several advantages to the application of forward genetic strategies because parthenogenetic females can reproduce clonally and without recombination. Consequently, mothers and daughters are genetically identical. Aphid genetics has a unique advantage over the use of other insects in that one can maintain induced mutations in a heterozygous state. Aphids can also reproduce sexually, allowing defined genetic crosses to be made. Mutations can be homozygosed by simple brother sister mating.
Tagu et al have used EMS to generate mutations as part of an effort to develop a forward genetic approach to the study of aphids. Their results certainly are enticing.
Tracking down causal point mutations requires other genetic resources and the problems of linking genotype and phenotype remain substantial. Transposon-based mutagenesis and other transposon-based forward genetic technologies such as gene-trapping would be a boon to the study of aphids. The significant efforts required to develop those technologies would certainly be richly rewarded.
April 1, 2014 vol. 4 no. 4 657-667G3