Abstract:
Plants and insects interact with each other in a variety of ways. Insects feed on
plants in the majority of plant-insect interactions. Plants challenge insect herbivory
via several defense mechanisms such as physical barriers to herbivory, secretion of
toxic chemicals, and secretion of volatiles that attracts insect’s predators. Insects, in
turn, have evolved defense strategies such as rapid excretion, detoxification or
sequestration of toxic chemicals, and behavioural avoidance of predators. Small
RNAs (sRNAs) are certain molecules that are seen to be upregulated in the plant
post-herbivory, the role of which has not yet been studied in this interaction. Our
study focuses on exploring the role of Arabidopsis thaliana (plant) – derived miRNAs
(type of sRNA) interacting with Plutella xylostella (insect) genes. It is one of the few
studies investigating the presence and role of exogenous diet-derived plant miRNAs
in an insect herbivore. In this study, three A. thaliana miRNAs targeting P. xylostella
GSS transcripts were predicted. The temporal kinetics of these candidate miRNAs
was observed in A. thaliana upon herbivory by P. xylostella. Pre and mature forms of
the miRNAs are seen to be induced at 12h and 24h post-herbivory. Temporal
kinetics of insect GSS genes was also observed. Candidate miRNAs were
synthesized via in vitro transcription and fed to P. xylostella larvae via an artificial
diet. We were not able to observe silencing of insect GSS genes through diet-fed
plant miRNAs.
