Replication Protein A2c Coupled with Replication Protein A1c Regulates Crossover Formation during Meiosis in Rice    

Abstract

Replication protein A (RPA) is a conserved heterotrimeric protein complex comprising RPA1, RPA2, and RPA3 subunits involved in multiple DNA metabolism pathways attributable to its single-stranded DNA binding property. Unlike other species possessing a single RPA2 gene, rice (Oryza sativa) possesses three RPA2 paralogs, but their functions remain unclear. In this study, we identified RPA2c, a rice gene preferentially expressed during meiosis. A T-DNA insertional mutant (rpa2c) exhibited reduced bivalent formation, leading to chromosome nondisjunction. In rpa2c, chiasma frequency is reduced by ;78% compared with the wild type and is accompanied by loss of the obligate chiasma. The residual ;22% chiasmata fit a Poisson distribution, suggesting loss of crossover control. RPA2c colocalized with the meiotic cohesion subunit REC8 and the axis-associated protein PAIR2. Localization of REC8 was necessary for loading of RPA2c to the chromosomes. In addition, RPA2c partially colocalized with MER3 during late leptotene, thus indicating that RPA2c is required for class I crossover formation at a late stage of homologous recombination. Furthermore, we identified RPA1c, an RPA1 subunit with nearly overlapping distribution to RPA2c, required for ;79% of chiasmata formation. Our results demonstrate that an RPA complex comprising RPA2c and RPA1c is required to promote meiotic crossovers in rice.

Resolvase OsGEN1 Mediates DNA Repair by Homologous Recombination

“…DSB formation is the first step in meiotic recombination and in rice can be assayed indirectly by detection of phosphorylated gH2AX (Mahadevaiah et al, 2001;Che et al, 2011). OsCOM1 and RPA2c are required for DSB end-processing and 39-single-strand invasion after DSB generation (Ji et al, 2012;Li et al, 2013) and DMC1 and RAD51C indicate the number of potential strand invasion events (Neale and Keeney, 2006;Tang et al, 2014). Our analysis showed that the localization of gH2AX, OsCOM1, RPA2c, DMC1, and RAD51C in osgen1 was indistinguishable to wild-type male meiocytes (Fig.…”

“…The polyclonal antibodies OsREC8, PAIR2, PAIR3, ZEP1, gH2AX, OsCOM1, RAD51C, and HEI10 used in this study were prepared according to Wang et al (2009Wang et al ( , 2010Wang et al ( , 2011Wang et al ( , 2012, Ji et al (2012), Miao et al (2013), and Tang et al (2014). The antibody against RPA2c was described in Li et al (2013). Antib-tubulin antibody was obtained from Sigma-Aldrich (catalog no.…”

Meiotic Recombination: The Essence of Heredity

“…Arabidopsis and Oryza possess multiple paralogs of the replication protein A (RPA) complex subunits and several rpa mutant alleles have been shown to specifically reduce class I crossovers, whereas overall DSB repair remains efficient (Osman et al 2009;Li et al 2013). In budding yeast, meiotic DSB repair shows a general dependence on RPA (Soustelle et al 2002), but RPA phosphorylation modulates crossover patterning (Bartrand et al 2006).…”

Factors Underlying Restricted Crossover Localization in Barley Meiosis

“…Compared to the large chromosomes of the cereal crops, rice (Oryza sativa) has a larger number of relatively small chromosomes (2n=2x=24) and a small genome ~420 Mb (14). However, during meiosis, wild-type metaphase I chromosome spreads revealed that bivalents consisted of a mixture of rods and rings with chiasma location biased towards the ends of chromosomes (59,92). The chiasma frequency and distribution was dramatically altered in a mutant of the rice synaptonemal complex transverse filament protein ZEP1 (92).…”