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Analysis of Arabidopsis XH/XS-Domain Proteins
May 15, 2012
SSE Biology Seminars-2012
Analysis of Arabidopsis XH/XS-Domain Proteins
by
Dr. Haroon Butt
PhD, University of Natural Resources and Life Sciences Vienna, Austria
Date: Tuesday, May 15, 2012,
Time: 11:30 – 12:30 pm
Venue: Smart Lab, CS, SSE LUMS
About the seminar
DNA methylation is an important epigenetic heritable mark, which is necessary for normal development in higher organisms. It involves reversible addition of a methyl group to carbon 5 of cytosine, which in turn modulates gene expression. The mechanism of de novo DNA methylation is still not fully understood, but the RNA directed DNA methylation (RdDM) pathway has been demonstrated to be involved. Recently, IDN2 (involved in de novo DNA methylation) was identified as an important component of de novo as well as siRNA-mediated maintenance methylation. IDN2 belongs to a plant specific Arabidopsis XH/XS-domain protein family, the function of which remains to be determined in further detail.
In this thesis the role of IDN2-RELATED (IDR) proteins were analysed. Gene expression analysis of IDR/IDN2 mRNA and selected promoter-GUS fusions revealed IDR expression at all developmental stages, specifically during the reproductive stage. Loss-of-function T-DNA insertion mutant lines in all 9 members of the IDR/IDN2 genes were identified and confirmed at transcriptional level. None of the identified single mutant lines as well as higher order mutant combinations exhibited any pronounced altered phenotypes under normal growth conditions but defects in maintenance methylation at selected loci could be observed. These defects were most pronounced in an idr1 idr2 idr3 idr4 idr5 idn2 hextuple mutant supporting the idea of functional redundancy among IDR/IDN2 genes.
