The role of OsMSH4 in male and female gamete development in rice meiosis.

Chaolong Wang,Fuqing Wu,Ling Jiang,Yang Yu,Peike Sheng,Weiwei Ma,Erchao Duan,Xiuping Guo,Yang Wang,Zhigang Zhao,Xin Zhang,Zhijun Cheng,Jun Chen,Linglong Liu,Jianmin Wan,Jiulin Wang,Ruizhen Qin

doi:10.1093/jxb/erv540

Abstract

Meiosis is essential for gametogenesis in sexual reproduction in rice (Oryza sativa L.). We identified a MutS-homolog (MSH) family gene OsMSH4 in a trisomic plant. Cytological analysis showed that developments of both pollen and embryo sacs in an Osmsh4 mutant were blocked due to defective chromosome pairing. Compared with the wild type, the Osmsh4 mutant displayed a significant ~21.9% reduction in chiasma frequency, which followed a Poisson distribution, suggesting that class I crossover formation in the mutant was impaired. Temporal and spatial expression pattern analyses showed that OsMSH4 was preferentially expressed in meiocytes during their meiosis, indicating a critical role in gametogenesis. Subcellular localization showed that OsMSH4-green fluorescent protein was predominantly located in the nucleus. OsMSH4 could interact with another MSH member (OsMSH5) through the N-terminus and C-terminus, respectively. Direct physical interaction between OsMSH5, OsRPA1a, OsRPA2b, OsRPA1c, and OsRPA2c was identified by yeast two-hybrid assays and further validated by pull-down assays. Our results supported the conclusion that the OsMSH4/5 heterodimer plays a key role in regulation of crossover formation during rice meiosis by interaction with the RPA complex.

Highlights

Meiosis is a key biological process in sexual reproduction which generates haploid gametes by a single round of DNA replication and is followed by two successive rounds of nuclear division
Strong interactions were detected between OsMSH5, OsRPA1a, and OsRPA2b, which were confirmed by pull-down assays in vitro (Fig. 8F, G). These results suggested that OsMSH4, OsMSH5, OsRPA1a, OsRPA2b, OsRPA1c OsRPA2c, and OsRPA3 might act as a complex in meiosis I
The majority of prokaryotic and eukaryotic MutS proteins belong to the lineage that participates in DNA mismatch repair (MMR), prevents homologous DNA recombination in heterologous sequences, and mediates cell death induced by DNA-damaging agents (Matic et al, 1996)

Summary

Introduction

Meiosis is a key biological process in sexual reproduction which generates haploid gametes by a single round of DNA replication and is followed by two successive rounds of nuclear division. Meiosis I is a reductional division in which homologous chromosomes pair, synapse, recombine, and segregate; and meiosis II involves the separation of sister chromatids (Zickler and Kleckner, 1999; Ma, 2006). Homologous chromosome recombination (HR) is initiated by a double strand break (DSB) in one of two participating chromosomes, to form crossovers (COs). As class I COs are sensitive to genetic interference, a relatively large distance is maintained between them, whereas class II COs are randomly distributed due to insensitivity to genetic interference (Mezard et al, 2007; Osman et al, 2011)

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Conclusion