Research in the department
of Molecular Evolution (AG Knoop) at the IZMB focuses on the following areas:
Molecular evolution of mitochondrial
DNA in early land plants
The mitochondrial DNA (mtDNA) in plants encodes more genes than in animals. More
importantly, the plant mtDNAs are characterized by many oddities such as
introns, trans-splicing, frequent recombination, foreign DNA inserts from the
chloroplast and nuclear genomes, RNA editing and an ongoing gene transfer to
the nucleus. We investigate the molecular evolution of these phenomena from a
phylogenetic viewpoint focussing on the evolutionary oldest groups of land plants:
the bryophyte clades of liverworts, mosses and hornworts and the early
tracheophyte clades of lycophytes, ferns and gymnosperms. In the latter groups
in particular we are in the process of sequencing complete mtDNAs from three
selected plant taxa (in co-operation with AG Prof. Bernd Weisshaar,
A gene family of membrane proteins
involved in transport of magnesium – the AtMRS2 gene family in Arabidopsis thaliana
This project line deals with a plant gene family of membrane proteins (~10
genes conserved across phylogenetically distant plants species) with two
transmembrane (TM) domains with the apparent main function of mediating magnesium
transport across biological membranes. These proteins are characterized by a
highly conserved GMN tripeptide motif behind the first TM domain and we thus
named them 2-TM-GMN proteins. They are ubiquitously present in all domains of
life including eukaryotes, archaea and eubacteria, but diversified into gene
families only in the plant lineage. The functional transporter in the membrane is
a pentamer. Our own experimental investigations include physiological analyses
of KO- and overexpressing plant lines, reporter gene studies to analyze protein
targeting and tissue-specific expression and protein-protein interaction
studies.
The DYW-type of PPR proteins in
early land plants with a focus on the model moss Physcomitrella patens
The enigmatic phenomenon of RNA editing in land plant organelles (site-directed
pyrimidine exchanges in transcripts) appears to correlate with the presence of a
specific subclade of the RNA-binding PPR proteins. PPR proteins are named after
the occurrence of Pentatricopeptide Repeat sequence motifs which are encoded by
vastly extended gene families with more than 400 members in flowering plants. In
particular, we investigate a plant-specific subclade of PPR proteins which are
characterized by a unique carboxyterminal extension ending in the DYW
tripeptide motif, the presence of which appears to clearly correlate with the occurrence
of RNA editing among the earliest land plants (initiated in co-operation with
the group of Ian Small, now
Further
projects investigated in collaboration with other research groups include
Molecular characterization of
kleptoplasts in Sacoglossa (sea slugs) with AG Prof. Heike Wägele
Molecular characterization of selected
plant-microbe interactions with AG Prof. em. E. Leistner
For further
information see our list of publications.