Genotypic variation among different phenotypes within aphid clones

Area of Science:

• Entomology
• Genetics
• Molecular Biology

Background:

• Aphids (Hemiptera: Aphididae) exhibit parthenogenesis and polyphenism, producing distinct adult morphs (e.g., winged, wingless) within asexual lineages.
• It is generally assumed that offspring from parthenogenetic aphid clones are genetically identical, barring sexual reproduction.
• Understanding genetic variation within clonal lineages is crucial for studying population dynamics and evolutionary processes in these insects.

Purpose of the Study:

• To investigate potential genetic differences between winged and wingless morphs within asexual clones of cereal aphids.
• To determine if molecular markers can distinguish between different aphid morphs originating from the same clone.
• To explore the implications of observed genetic variation for the understanding of clonal organisms.

Main Methods:

• Randomly amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) was employed to analyze DNA from different aphid morphs.
• Southern blotting and hybridization were used to confirm the origin of polymorphic DNA bands.
• Sequencing of specific DNA bands and analysis of genomic DNA treated to remove secondary structures were performed.

Main Results:

• RAPD-PCR revealed the presence or absence of specific DNA bands differentiating winged and wingless morphs in some clones of Sitobion avenae and Rhopalosiphum padi.
• Southern blotting confirmed that the discriminating DNA bands were of aphid origin.
• Sequenced bands were A/T rich, with one showing homology to muscle tissue, and differences persisted even after DNA structural modification.

Conclusions:

• Contrary to assumptions, genetic variations can exist between asexual morphs within the same aphid clone.
• RAPD-PCR is a viable method for detecting these subtle genetic distinctions.
• This finding has significant implications for understanding genetic identity and variation in clonal organisms like aphids.