The genetic basis of octanoic acid resistance in Drosophila sechellia | Shiv Nadar University
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The genetic basis of octanoic acid resistance in Drosophila sechellia

The Department of Life Sciences cordially invites you for the special research seminar by Dr. Joseph David Coolon in its ‘Scientific Seminar Series’.  

Drosophila sechellia is a species of fruit fly endemic to the Seychelles islands. Unlike its generalist sister species, D. sechellia has evolved to be a specialist on the host plant Morinda citrifolia. This specialization is interesting because the plant’s fruit contains secondary defense compounds, primarily octanoic acid (OA), that are lethal to most other Drosophilids. Although ecological and behavioral adaptations to this toxic fruit are known, the genetic basis for evolutionary changes in OA resistance are not. Prior work showed that 5 genomic regions contribute to this trait with a genomic region on chromosome 3R containing 18 genes having the greatest contribution to differences in OA resistance between resistant species D. sechellia and sensitive sister species D. simulans. Using protein inactivation, we ruled out the contribution of the well known cytochrome P450 and glutathione S-transferase gene families to this trait change and discovered that one or more genes in the esterase gene family do contribute evolved resistance in D. sechellia. To further interrogate the fine-mapped QTL region on chromosome 3R, we used a combination of RNA-seq and an RNAi gene expression knockdown screen and identified three neighboring genes in the Osiris family, Osiris 6 (Osi6), Osi7, and Osi8, that lead to decreased OA resistance when ubiquitously knocked-down in adults. Further dissection of the role these genes play in OA resistance found that tissue-specific environmental plasticity of Osi6 gene expression, evolved constitutive changes in gene expression of Osi7, and protein coding changes in Osi8 may all contribute to OA resistance in D. sechellia. Osiris represents a new class of genes implicated in evolved insect resistance to chemicals and ongoing studies in the lab are investigating the biochemical, cellular and genetic mechanisms involved in evolution of toxin resistance through this newly described gene family with the goal to apply these findings to cases of economically important insect pests that have evolved resistance to insecticides for development of new approaches for pest control.

Event Date: 
Wednesday, January 11, 2023 - 00:00
Wednesday 11, Jan 2023

Block C-021, Shiv Nadar IoE Campus