The DNA Topoisomerase VI–B Subunit OsMTOPVIB Is Essential for Meiotic Recombination Initiation in Rice

Abstract

In flowering plants, the life cycle alternates between diploid sporophyte and haploid 7 gametophyte generations. Development of the male organ and germ cells is essential 8 for successful plant fertility and crop yield. Male reproduction is a highly orchestrated 9 process controlled by various intrinsic components. Although significant advances 10 have been made in understanding male gametophyte formation, the molecular 11 mechanisms controlling in this process are still largely unknown (Zhang et al., 2016). 13To identify male sterility genes in rice, we have constructed a mutant library by 14 treating the rice cultivar 9522 (Oryza sativa ssp. Japonica) with gamma ray radiation. 15This has led to the identification of two allelic male sterile mutants that we have that OsMTOPVIB is essential for DSB formation in rice ( Figure 1D). and that pre-DSB sites originate in the chromosome loops before moving to the axes.

Interconnections between meiotic recombination and sequence polymorphism in plant genomes

“…Meiotic recombination initiates via the generation of DNA double strand breaks (DSBs) by SPO11 transesterases, which act in topoisomerase-VI-like complexes (Keeney & Neale, 2006;Fu et al, 2016;Robert et al, 2016;Vrielynck et al, 2016) (Fig. 1).…”

A Multiprotein Complex Regulates Interference-Sensitive Crossover Formation in Rice

“…Homologous recombination is initiated by the induction of programmed double-strand breaks (DSBs). DSBs are generated by a widely conserved sporulation 11 (SPO11)-meiotic topoisomerase VIB-like (MTOPVIB) protein complex (Fu et al, 2016;Robert et al, 2016;Vrielynck et al, 2016;Xue et al, 2016). DSBs are processed by the radiation-sensitive 50 (RAD50)-meiotic recombination 11-X-ray sensitive 2 complex to produce 39-single-stranded DNA (ssDNA) tails that are bound sequentially by replication protein A and recombinases RAD51 and DNA meiotic recombinase 1 (DMC1).…”

Bivalent Formation 1, a plant-conserved gene, encodes an OmpH/coiled-coil motif-containing protein required for meiotic recombination in rice

“…5C–F), supporting the idea that OsBVF1 functions upstream of DSB end procession. This hypothesis was further supported by the undetectable signal of the other downstream proteins OsDMC1 (Wang et al , 2016) and OsMER3 (Wang et al , 2009) in bvf1 mutant meiocytes (Fig. 5G–J).…”

“…After removing the coverslip, the slides were marked by a stain circle pen and incubated in washing buffer I (1×PBS with 1% (v/v) Triton X-100) for an hour at room temperature. Then slides were incubated with the primary antibodies, including anti-γH2AX (raised in rabbit; Miao et al , 2013), OsREC8 (raised in both rabbit and mouse; Shao et al , 2011), OsMER11 (raised in mouse; Ji et al , 2013), OsCOM1 (raised in mouse; Ji et al , 2012), OsDMC1 (raised in mouse; Wang et al , 2016), OsMER3 (raised in mouse; Wang et al , 2009), OsPAIR2 (raised in mouse; Wang et al , 2009) or anti-OsZEP1 (raised in mouse; Wang et al , 2010) antibody solution (diluted 1:200 in blocking buffer: 1×PBS, 1 mM EDTA, 0.1% Tween 20, 5% BSA), at 4 o C overnight. After three rounds of washing in washing buffer II (1×PBS with 0.1% (v/v) Tween 20), Alexa Fluor 488-conjugated goat anti-mouse secondary antibody or Alexa Fluor 555-conjugated donkey anti-rabbit secondary antibody (Beyotime, Shanghai, China) was added to the slides.…”

“…In Arabidopsis, AtPRD1/2/3, AtDFO, AtPCH2, and MTOPVIB were required for DSB formation (De Muyt et al , 2007; De Muyt et al , 2009; Zhang et al , 2012; Lambing et al , 2015; Vrielynck et al , 2016). By contrast, only OsPAIR1, OsCRC1, OsSDS, and OsMTOPVIB were characterized as being DSB formation related in rice (Nonomura et al , 2004 a ; Miao et al , 2013; Wu et al , 2015; Fu et al , 2016; Xue et al , 2016). It seems that divergence of regulation of meiotic progression exists between rice and Arabidopsis.…”