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Exploring Cannabis sativa's response to powdery mildew (Golovinomyces ambrosiae) infection Quesada-Ramirez, Lucia

Abstract

Powdery mildew infection, which is caused by the fungal pathogen Golovinomyces ambrosiae (Erysiphaceae), has been extensively characterized in Arabidopsis (Brassicaceae), and other species, but not in Cannabis sativa (Cannabaceae), a commercially important plant species. In this thesis, I explore the response of C. sativa to powdery mildew infection. I used microscopy to examine the phenotypic response and RNA-sequencing to examine the transcriptomic response to powdery mildew. I also examined differences between resistant (AGA10) and susceptible (Purple Kush) genotypes. Microscopy revealed that there are differences between the two genotypes in germination and hypersensitive response (programmed cell death). RNA-sequencing revealed differences in expression of genes encoding enzymes of the phenylpropanoid and monolignol biosynthetic pathways, phytoalexin production, and other plant-pathogen responses. Gene ontology (GO) functional analysis shows that the two genotypes also differ in expression of genes related to carbohydrate metabolic processing and other enzymatic processes. I conclude that a likely main factor behind the AGA10 resistant phenotype is increased reactive oxygen species and hypersensitive response, due to earlier or increased expression of genes such as oxidoreductases, peroxidases, phenylalanine ammonia lyase and trans-cinnamate 4-monooxygenase.

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Attribution-NonCommercial-NoDerivatives 4.0 International