Ashley Smith



Document Type



Root-knot nematodes (Meloidogyne spp.) are a major problem in the United States; damaging millions of dollars’ worth of crops every year. It is believed that root-knot nematodes (RKN) alter the expression of JAZ gene family members in the plant, Arabidopsis thaliana, but there is not much documentation on which genes change expression and why. The JAZ genes are transcriptional regulators in the signaling pathway for the plant hormone, Jasmonic acid, which controls certain aspects of plant defense. There are twelve JAZ genes in Arabidopsis but it is unclear if they each have distinct roles in Jasmonic acid defense signaling. First, the levels of JAZ gene expression in Arabidopsis roots without nematodes were examined. Then the differences in expression after the addition of root-knot nematodes to the plants were examined. Arabidopsis seedlings were grown on sterile petri dishes for two weeks then juvenile nematodes were added. After two, six, 13 and 20 days, the RNA was extracted from the roots. The RNA was turned into complimentary DNA (cDNA) by reverse transcription to use it in quantitative Polymerase Chain Reaction (qPCR). qPCR can quantitate the amount of expression for each of the twelve JAZ genes after nematode infection, compared to the uninfected plants. The JAZ genes that changed significantly in presence of the nematodes were JAZ 9 and 10. JAZ 1 and 5 showed trends of altered expression with RKN but more replicates are required. GUS staining was performed on transgenic Arabidopsis lines carrying JAZ1 and JAZ12 promoter::GUS fusions and both showed that expression was localized to the roots, specifically the RKN knots for JAZ12.



Thesis Comittee

Heather Marella (Thesis Director)

Jenna Mendell

Jonathan Roling

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Original document was submitted as an Honors Program requirement. Copyright is held by the author.

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