Gene Expression Profiling of the nip Mutant in Medicago truncatula

The study of root nodule symbiosis between nitrogen-fixing bacteria and leguminous plant species is important because of the ability to supplement fixed nitrogen fertilizers and increase plant growth in poor soils. Our group has isolated a mutant called nip in the model legume Medicago truncatula that is defective in nodule symbiosis. The nip mutant (numerous infections with polyphenolics) becomes infected by Sinorhizobium meliloti but then accumulates polyphenolic defense compounds in the nodule and fails to progress to a stage where nitrogen fixation can occur. Analysis of the transcriptome of nip roots prior to inoculation with rhizobia was undertaken using Affymetric Medicago Genome Array microarrays. The total RNA of 5-day old uninoculated seedlings was analyzed in triplicate to screen for the NIP gene based on downregulated transcript levels in the mutant as compared to wild type. Further microarray data was generated from 10 days post inoculation (dpi) nip and wild type plants. Analysis of the most highly downregulated transcripts revealed that the NIP gene was not identifiable based on transcript level. Putative gene function was assigned to transcripts with altered expression patterns in order to characterize the nip mutation phenotypically as inferred from the transcriptome. Functional analysis revealed a large number of chaperone proteins were highly expressed in the nip mutant, indicating high stress in the mutant prior to infection by rhizobia. Additionally, a database containing the information regarding the nip expression profile at both 0 days post inoculation (dpi) and 10 dpi were created for screening of candidate genes as predicted from sequence in the genomic region containing NIP.

Grantor dc:publisher

University of North Texas

Year dc:date

2007

Author dc:creator

• McKethan, Brandon Lee

Contributors dc:contributor

• Dickstein, Rebecca
• González, Juan E.
• Benjamin, Robert C.

• gene expression
• transcriptome
• expression profiling
• microarray
• Medicago -- Genetics.
• Rhizobium.

Statement dc:rights

• Public
• Copyright
• McKethan, Brandon Lee
• Copyright is held by the author, unless otherwise noted. All rights reserved.

Language dc:language

English

Identifier

oclc: 191500840
https://digital.library.unt.edu/ark:/67531/metadc3940/
ark: ark:/67531/metadc3940

OAI identifier oai:identifier

info:ark/67531/metadc3940