Progress in clarifying the genetic mysteries of photosynthesis
Although scientists have sequenced the genomes of many organisms, they still lack a context that allows them to associate the proteins encoded in genes with specific biological processes.
To better understand the underlying genetics in plant physiology and ecology, especially with regard to photosynthesis, a team of researchers worked to identify a number of proteins that are encoded in the genomes of plants and green algae, but who are not in the genomes of organisms that do not generate energy through photosynthesis.
Using advanced computational tools for analyzing the genomes of 28 different plants and photosynthetic organisms, Arthur Grossman of the Carnegie Institution of Washington and colleagues from the University of California at Los Angeles and the Joint Genome Institute, also in the United States have identified 597 proteins encoded in genomes of plants and green algae, but are not present in non-photosynthetic organisms.
Interestingly, of the 597 proteins in this group, 286 have known functions, while the remaining 311 do not know how biological processes are interrelated and their function is, therefore, known in outline.
The majority (52 percent) of the proteins encoded in the genomes of plants and green algae but is not present in non-photosynthetic organisms, have been located in a cellular organelle called the chloroplast, the compartment where photosynthesis takes place.
It is widely accepted that chloroplasts originated from unicellular photosynthetic bacteria called cyanobacteria, which were absorbed by a cell more complex, non-photosynthetic, more than 1,500 million years. Although the relationship between the two agencies was originally symbiotic, over evolutionary time cyanobacteria transferred most of their genetic information to the nucleus of the host organism, losing their ability to live independently of their partner.
This reduced genetic cyanobacteria, which is now a chloroplast that has maintained its ability to perform photosynthesis and other essential metabolic functions such as the synthesis of amino acids and fats.
The processes taking place in the chloroplast should also be closely integrated with metabolic processes that occur in other parts of the cell outside the chloroplast.