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EMBO Plant DNA Repair and Recombination Workshop, Presqu'île de Giens, France 2007
suggested by its interaction with Dmc1. EMBO J 23:1392-1401 10. Molinier et al (2004)
Interchromatid and Interhomolog Recombination in Arabidopsis thaliana. The Plant Cell,
16 : 342-35
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P - 15. AtMUS81 and its Genetic Interactions with RecQ-Helicases in Arabidopsis
thaliana
Frank Hartung, Stefanie Suer, Andreas Braun, Tina Bergmann, Holger Puchta. Botanical
Institute II, University of Karlsruhe, 76128 Karlsruhe, Germany
The endonuclease MUS81 has been shown in a variety of organisms to be involved in DNA
repair in mitotic and meiotic cells. Homologues of the MUS81 gene exist in the genomes
of all eukaryotes, pointing to a conserved role of the protein. However, the biological role
and meiotic significance of MUS81 varies between different eukaryotes. For example,
while loss of the gene results in strongly impaired fertility in S. cerevisiae and nearly
complete sterility in S. pombe, it is not essential for meiosis in mammals. We identified a
structural and functional homologue (AtMUS81/At4g30870) in the genome of
Arabidopsis thaliana and determined the full-length cDNA of this gene, using RACE
technology. Analysing two independent T-DNA insertion mutant lines of AtMUS81, we
found that they are sensitive to the mutagens MMS and MMC but not to bleomycin. In
contrast to yeast, no meiotic defect of Atmus81-1 and 2 was detectable resulting in a
normal fertility. Crosses of Atmus81-1 with a hyperrecombinogenic mutant of the
AtRECQ4A helicase resulted in synthetic lethality in the double mutant, whereas other
AtRECQ genes tested did not show this effect. Thus, the nuclease AtMUS81 and the
helicase AtRECQ4A seem to be involved in two alternative pathways of resolution of
replicative DNA structures in somatic cells and the knock out of both pathways leads to
plant lethality.
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P - 16. Meiotic recombination frequency analysis in Arabidopsis thaliana mutants
Veena Hedatale, Tony Connors, Tom Gerats, Janny Peters. Plant Genetics, Radboud
University, 6525 ED Nijmegen, India
Using sequence data from cDNA AFLP-based transcript profiles in Petunia undergoing
male meiosis (Cnudde et al., 2006), we are trying to understand the roles of the
corresponding Arabidopsis genes in homologous recombination. In order to estimate
recombination frequency in meiotic mutants, we are employing a previously described
fluorescent seed-based assay (Melamed-Bessudo et al, 2005). In addition to the available
tester line from Melamed-Bessudo and colleagues, four new tester lines were developed,
consisting of GFP and RFP markers linked in cis on three different chromosomes. In the
future we plan to generate meiotic testers for all five Arabidopsis chromosomes. The
available tester lines were crossed to several mutants to monitor the effect of meiotic
genes on meiotic recombination. From the F2 population plants heterozygous for the
fluorescent markers and homozygous for the mutant or wild-type locus were selected. By
backcrossing the selected plants to a male sterile line, the recombination rate in the GFP-
RFP marker interval of these plants can be compared to determine the effect of the
mutation on recombination frequency. References: 1. Cnudde F, Hedatale V, de Jong H,
Pierson ES, Rainey DY, Zabeau M, Weterings K, Gerats T, Peters JL (2006), Changes in gene
expression during male meiosis in Petunia hybrida, Chromosome Res. 14:919-932. 2.
Melamed-Bessudo C, Yehuda E, Stuitje AR, Levy AA. (2005), A new seed-based assay for
meiotic recombination in Arabidopsis thaliana, Plant J 43:458-466.
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