AtMND1 is required for homologous pairing during meiosis in Arabidopsis.
BACKGROUND
Pairing of homologous chromosomes at meiosis is an important requirement for recombination and balanced chromosome segregation among the products of meiotic division. Recombination is initiated by double strand breaks (DSBs) made by Spo11 followed by interaction of DSB sites with a homologous chromosome. This interaction requires the strand exchange proteins Rad51 and Dmc1 that bind to single stranded regions created by resection of ends at the site of DSBs and promote interactions with uncut DNA on the homologous partner. Recombination is also considered to be dependent on factors that stabilize interactions between homologous chromosomes. In budding yeast Hop2 and Mnd1 act as a complex to promote homologous pairing and recombination in conjunction with Rad51 and Dmc1.


RESULTS
We have analyzed the function of the Arabidopsis orthologue of the budding yeast MND1 gene (AtMND1). Loss of AtMND1 did not affect normal vegetative development but caused fragmentation and missegregation of chromosomes in male and female meiosis, formation of inviable gametes, and sterility. Analysis of the Atmnd1 Atspo11-1 double mutant indicated that chromosome fragmentation in Atmnd1 was suppressed by loss of Atspo11-1. Fluorescence in situ hybridization (FISH) analysis showed that homologous pairing failed to occur and homologues remained apart throughout meiosis. AtMND1 showed strong expression in meiocytes as revealed by RNA in situs.


CONCLUSIONS
We conclude that AtMND1 is required for homologous pairing and is likely to play a role in the repair of DNA double strand breaks during meiosis in Arabidopsis, thus showing conservation of function with that of MND1 during meiosis in yeast.
Panoli
Aneesh P
AP
Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad - 500007, India. aneeshpp@ccmb.res.in
Ravi
Maruthachalam
M
Sebastian
Jose
J
Nishal
Bindu
B
Reddy
Thamalampudi V
TV
Marimuthu
Mohan P A
MP
Subbiah
Veeraputhiran
V
Vijaybhaskar
Virupapuram
V
Siddiqi
Imran
I
D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D043283:Chromosome Fragile Sites; D023902:Chromosome Pairing; D032461:Chromosomes, Plant / Q000378:metabolism; D015870:Gene Expression; D005854:Germ Cells / Q000378:metabolism; D008540:Meiosis / Q000235:genetics*; D009154:Mutation; D051479:Plant Infertility / Q000235:genetics; D010940:Plant Proteins / Q000502:physiology; D012098:Reproduction / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014018:Tissue Distribution; D000099257:Meiotic Recombination Protein SPO11
D029681:Arabidopsis Proteins; D002868:Chromosomal Proteins, Non-Histone; D010940:Plant Proteins; D029701:Saccharomyces cerevisiae Proteins; C454441:MND1 protein, S cerevisiae; C477460:Spo11-1 protein, Arabidopsis; D000099257:Meiotic Recombination Protein SPO11