Polycomb Group Gene OsFIE2 Regulates Rice (Oryza sativa) Seed Development and Grain Filling via a Mechanism Distinct from Arabidopsis

Abstract

Cereal endosperm represents 60% of the calories consumed by human beings worldwide. In addition, cereals also serve as the primary feedstock for livestock. However, the regulatory mechanism of cereal endosperm and seed development is largely unknown. Polycomb complex has been shown to play a key role in the regulation of endosperm development in Arabidopsis, but its role in cereal endosperm development remains obscure. Additionally, the enzyme activities of the polycomb complexes have not been demonstrated in plants. Here we purified the rice OsFIE2-polycomb complex using tandem affinity purification and demonstrated its specific H3 methyltransferase activity. We found that the OsFIE2 gene product was responsible for H3K27me3 production specifically in vivo. Genetic studies showed that a reduction of OsFIE2 expression led to smaller seeds, partially filled seeds, and partial loss of seed dormancy. Gene expression and proteomics analyses found that the starch synthesis rate limiting step enzyme and multiple storage proteins are down-regulated in OsFIE2 reduction lines. Genome wide ChIP–Seq data analysis shows that H3K27me3 is associated with many genes in the young seeds. The H3K27me3 modification and gene expression in a key helix-loop-helix transcription factor is shown to be regulated by OsFIE2. Our results suggest that OsFIE2-polycomb complex positively regulates rice endosperm development and grain filling via a mechanism highly different from that in Arabidopsis.

Genome-Wide Mapping of Targets of Maize Histone Deacetylase HDA101 Reveals Its Function and Regulatory Mechanism during Seed Development

“…Beads were heated for 10 min at 70°C with 40 mL 13 loading buffer (50 mM Tris HCl, pH 6.8, 10% glycerol, 2% SDS, and 5% b-mercaptoethanol). Purified proteins were separated by 10% SDS-PAGE.The gels were stained by silver staining,and all visualized bands were digested with trypsin (final concentration 0.067 µg/µL) and identified using liquid chromatography-tandem mass spectrometry analysis as previously described (Nallamilli et al, 2013).…”

Rice Fertilization-Independent Endosperm1 Regulates Seed Size under Heat Stress by Controlling Early Endosperm Development

“…Orthologs of the Arabidopsis FIE gene have been reported in both rice (OsFIE1 and OsFIE2) and maize (ZmFIE1 and ZmFIE2; Springer et al, 2002;Danilevskaya et al, 2003;Luo et al, 2009). OsFIE1 is expressed only in the endosperm, whereas OsFIE2 is expressed in all tissues tested (Luo et al, 2009;Nallamilli et al, 2013). OsFIE1 is an imprinted gene, and its expression is regulated by DNA and H3K9me2 methylation (Luo et al, 2009;Zhang et al, 2012).…”

Plant Long ncRNAs: A New Frontier for Gene Regulatory Control

“…It should be noted that PRC2 is recruited by lncRNAs in several reported cases, implying a widespread of the lncRNA-PRC2 gene silencing mechanism in different species [47]. So far, the question concerning how is PRC 2 recruited to the right chromatin region has not been fully addressed.…”