Histone3 variants in plants

Abstract

Regulation of chromatin activity by covalent histone modifications has been long recognized. Histones that constitute the nucleosome are encoded by large families of genes and display a strong degree of conservation. However, histone variants exist and it is becoming clear that they play important roles in genome regulation. While most studies of the role of histone3 (H3) variants in transcriptional control comes from animal models, emerging data in plants suggest functional conservation, although plant-specific roles are likely. We review these data and speculate on the biological significance of H3 variants in plants.

Genome-wide analysis of histone H3.1 and H3.3 variants in Arabidopsis thaliana

“…Notably, we found similar trends as seen in animals, even though H3 variants have evolved independently in plants and animals (7,8), suggesting convergent evolution.…”

“…Plants and animals share the components involved in H3 dynamics, including canonical and variant H3 proteins, gene structures, and the chaperones responsible for their deposition (2,7). In addition, extensive conservation in the amino acid sequences and expression patterns of histones H3.1 and H3.3 is seen in animals and plants, despite evidence that H3.1 and H3.3 evolved independently in the two kingdoms based on analyses of amino acid sequences (1,2,7,8); for instance, in both plants and animals, H3.3 differs from H3.1 at only three or four amino acid positions (2,9).…”

“…In addition, extensive conservation in the amino acid sequences and expression patterns of histones H3.1 and H3.3 is seen in animals and plants, despite evidence that H3.1 and H3.3 evolved independently in the two kingdoms based on analyses of amino acid sequences (1,2,7,8); for instance, in both plants and animals, H3.3 differs from H3.1 at only three or four amino acid positions (2,9). Histone H3 variants have been profiled at a genome-wide level in Drosophila and mammalian cells (5,10,11).…”

Sperm entry is sufficient to trigger division of the central cell but the paternal genome is required for endosperm development in Arabidopsis

“…These minor classes of seeds had not been recognized in the previous report (Nowack et al, 2006), and their conclusion of preferential fertilization of the egg cell is not supported by our analysis. Earlier studies of other mutants had also concluded that both female gametes could be fertilized by single sperm cells (Chen et al, 2008;Frank and Johnson, 2009), or that both wildtype sperm cells were able to fertilize multiple egg cells from mutant ovules (Ingouff et al, 2010;Pagnussat et al, 2007). Our results thus further support that, in Arabidopsis, both sperm cells are able to fertilize either the egg cell or the central cell.…”

“…Determination of the timing of transcriptional onset after fertilization HTR10 is a very divergent H3 variant (Okada et al, 2005) and its predominant incorporation in sperm cell chromatin indicates that it could be involved in large-scale expression regulation or chromatin compaction (Ingouff and Berger, 2010). We thus investigated in detail fertilization and early seed development following pollination from cdka;1/+ plants.…”