Chloroplast Genome

Abstract

Chloroplasts contain a genome that is a relic of the endosymbiont that gave rise to the organelle. These genomes typically contain 100–200 genes and encode proteins important for photosynthesis and other chloroplast functions, although dinoflagellate algae have a greatly reduced and fragmented chloroplast genome. Many nonphotosynthetic taxa retain a remnant chloroplast genome. In some organisms the chloroplast genome may be retained to allow redox‐mediated control of gene expression, whereas in others it may continue to exist because transfer of essential genes to the nucleus is no longer possible. Multiple ribonucleic acid (RNA) polymerases are involved in chloroplast transcription in land plants, and post‐transcriptional processing involving nuclear‐encoded RNA‐binding proteins also plays an important part in the expression of the chloroplast genome. Gene expression may be regulated at a number of levels, and redox poise in the organelle may be particularly important for this. Key Concepts: Chloroplasts originated in the ancestor of plants and red and green algae by endosymbiotic acquisition of a cyanobacterium, and then spread to many other eukaryotic lineages. There are other examples of stable acquisition of a cyanobacterium by a nonphotosynthetic host. Chloroplast genomes are typically 100–200 kbp in size, and include a set of genes for proteins essential to photosynthesis. Other genes present in the ancestral symbiont have been lost or relocated to the nucleus. Many nonphotosynthetic organisms retain remnant chloroplasts, with genomes, reflecting the fact that photosynthesis is not the only biochemical process that takes place in the chloroplast. In many organisms, gene transfer from chloroplast to nucleus can still take place, at an unexpectedly high frequency. Establishment of the chloroplast has resulted in the development of nuclear‐encoded RNA‐binding protein families and, in land plants, additional RNA polymerases that play a central role in chloroplast gene expression. Post‐transcriptional RNA processing plays an important role in chloroplast gene expression. In photosynthetic organisms, chloroplast gene expression is closely linked to the organelle's redox poise. The chloroplast can also influence the expression of nuclear genes.

Complete Chloroplast Genome Features of Dendrocalamusfarinosus and Its Comparison and Evolutionary Analysis with Other Bambusoideae Species

“…The cp has an independent semi-autonomous extranuclear genome [ 9 ]. The cp genome is the crucial genetic material of plants, encoding 100–200 essential genes which encode proteins involved in photosynthesis and other chloroplast functions [ 10 ]. Moreover, the cp genomes are ideal tools for studying evolutionary relationships between species because cp genomes are very conserved, and their heredity is independent of the nucleus [ 11 , 12 ].…”

The chloroplast genome of Cerasus humilis: Genomic characterization and phylogenetic analysis

“…The chloroplast genome is a closed cyclic structure that consists of large single copy (LSC), small single copy (SSC), and two reverse repeats (IR); its genome size ranges from 100 kb to 200 kb. Protein-coding genes are important in photosynthesis and other functions of the chloroplast and are further divided into nine categories: Photosystem I, cytochrome b6-f complex, Photosystem II, ATP synthase, ribulose bis-phosphate carboxylase, ribosome large subunit, ribosome small subunit, RNA polymerase, and a hypothetical protein [ 11 ]. The overall structure and genome of the chloroplast are relatively conserved, although in-depth studies in chloroplast genomics and biology have identified several mutations and small structural changes among various species including insertions, deletions, reversals, and translocations [ 12 , 13 ].…”

Experimental and genomic evidence for the indica-type cytoplasmic effect in Oryza sativa L. ssp. japonica

“…The chloroplast genome is a relic of a endosymbiont that that was integrated into the cell and utilized as an organelle; it typically contains 100-200 genes and encodes proteins involved in photosynthesis and other chloroplast functions (Howe 2012). Chloroplast-to-nucleus retrograde signaling is triggered through pathways such as the Mg-ProtoIX dependent pathway and the plastid gene expression-dependent pathway (Nott et al 2006).…”