OsAM1 is required for leptotene-zygotene transition in rice

Abstract

The events occurring at the onset of meiosis have not been fully elucidated. In the present study, OsAM1 was identified in rice (Oryza sativa L.) by map-based cloning. OsAM1, a homolog of Arabidopsis SWI1 and maize AM1, encodes a protein with a coiled-coil domain in its central region. In the Osam1 mutant, pollen mother cells are arrested at leptotene, showing that OsAM1 is required for the leptotene-zygotene transition. Immunocytological analysis revealed that OsAM1 exists as foci in early prophase I meiocytes. Very faint OsREC8 foci persisted in the Osam1 mutant, indicating that OsAM1 is not required for the initial meiotic recruitment of OsREC8. In the absence of OsAM1, many other critical meiotic components, including PAIR2, ZEP1 and OsMER3, could not be correctly installed onto chromosomes. In contrast, in pair2, Osmer3 and zep1 mutants, OsAM1 could be loaded normally, suggesting that OsAM1 plays a fundamental role in building the proper chromosome structure at the beginning of meiosis.

Molecular Control of Induced Pluripotency

“…An investigation of population-level chromatin dynamics during the initial stages of reprogramming reported the genome-wide redistribution of histone H3 lysine 4 dimethylation (H3K4me2), a mark associated with euchromatin, at thousands of loci (Koche et al, 2011). In comparison, little change was observed in the distribution of histone H3 lysine 27 trimethylation (H3K27me3), a transcriptional-silencing-associated marker, except for highly localized depletion at promoters that acquired histone H3 lysine 4 trimethylation (H3K4me3), an activation-associated marker.…”

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).…”

Somatic and Reproductive Cell Development in Rice Anther Is Regulated by a Putative Glutaredoxin

“…Rice proteins AM1 and REC8 are localized to meiotic chromosomes quite early at meiotic prophase I Che et al, 2011;Shao et al, 2011). To define the relationship between these two proteins and MIL1, MIL1 immunolocalization was investigated in anther squashes from the rice am1 mutant and rec8 mutant, in combination with CENH3.…”

“…Histological studies were performed as previously described with minor modifications Che et al, 2011). Wild-type, mil1, and msp1-5 spikelets representing various developmental stages were fixed in FAA (5% formaldehyde, 5% glacial acetic acid, and 63% ethanol) or Carnoy's solution (ethanol:glacial acetic acid, 3:1) overnight at 48C.…”