Linking transposable element regulatory mechanisms with overcoming host plant resistance by the soybean aphid, Aphis glycines

Epigenetic influence on insect adaptation, particularly for overcoming host plant resistance, is an emerging field of study. Aphids are currently a model organism for this area of research since they regularly use epigenetic regulation to produce phenotypic changes across generations. This change is often adaptive, particularly under stress. One such stress come from natural plant defenses against aphid infestation. However, for the soybean aphid, certain biotypes have adapted to survive and reproduce on resistant soybean. This adaptation may be epigenetically controlled since virulent aphids overexpress several different types of transposable elements (TEs), potentially due to an impaired regulatory system. One such system is through PIWI proteins, which use small RNAs (sRNA) to control the expression of TEs. PIWI gene expression is unknown in the soybean aphid. To answer this, we will measure expression levels of five PIWI genes found in A. glycines to identify any differential expression between virulent and avirulent aphids. Aphids will be reared in lab conditions on susceptible and resistant soybeans. Lab colony aphids will be compared to aphids collected from soybean fields across five states within the U.S. to identify any differential expression. We expect to find differential expression of at least one PIWI gene, which may be linked to differential expression of TEs. Our data will show the role that PIWI proteins and TE expression could have a role in insect adaptation and overcoming resistance.