Date of Graduation

Summer 2024

Degree

Master of Science in Biology

Department

Biology

Committee Chair

Laszlo G. Kovacs

Abstract

Agricultural insecticides are formulated to target insects while minimizing harm to the intended crop. In rare instances, however, insecticides induce harmful physiological reactions in certain plant genomes, inflicting severe tissue damage. This project investigated the genetic basis of such a reaction observed in the grape genotype Vitis rupestris B38 following exposure to the insecticide carbaryl, which manifests as interveinal leaf necrosis. Through analysis of an F1 hybrid progeny of this grapevine, I mapped this phenotype to a QTL on chromosome 16. The carbaryl-sensitive trait was repeatedly mapped to the same locus using phenotype data from two different field locations and from an in vitro bioassay. RNA-seq and gene ontology enrichment analyses revealed the activation of various defense- and stress-related mechanisms, and strongly suggested the involvement of salicylic acid- and jasmonic acid-dependent defense responses. The RNA-seq data suggested a misdirected hypersensitive response (HR) in sensitive plants; differentially expressed genes (DEGs) associated with plant pathogen defense pathways further support this speculation. However, RT-qPCR analysis of NDR1/HIN1-like protein 6 gene expression did not validate the involvement of such pathways, therefore, further molecular analysis is needed to fully elucidate the underlying mechanisms of carbaryl sensitivity. Altogether, the findings of this thesis highlight the intricate interplay of plant defense pathways in response to xenobiotic stressors and emphasize the ecological significance of plant-insecticide interactions.

Keywords

carbaryl, interveinal necrosis, Vitis rupestris, RNA-seq analysis, QTL, F1 hybrid progeny, RT-qPCR, hypersensitive response

Subject Categories

Agriculture | Biology | Genetics and Genomics | Plant Sciences | Viticulture and Oenology

Copyright

© Courtney Nicole Duncan

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