by Staff Writers
London, UK (SPX) Aug 31, 2011
Plants produce a vast array of natural products, many of which we find useful for making things such as drugs. There are likely to be many other plant natural products that remain undiscovered or under-exploited, and research from The John Innes Centre, which is strategically funded by the Biotechnology and Biological Sciences Research Council (BBSRC), is uncovering more about the genetics and evolution of natural product pathways in plants.
Researchers at JIC have recently discovered that the genes producing two of these products in the model plant Arabidopsis are clustered together, which is extremely rare in plants.
An apparent 'evolutionary playground' in the plant's genome seems to have brought the genes together, and knowing how these clusters assemble and are controlled will be important for improving and exploiting the production of new natural products.
Gene clusters are common in bacteria, where genes needed to perform a specific task, such as producing an antibiotic, are grouped together in what are called operons. However in plants and animals, functionally related genes are normally spread throughout the genome.
Professor Anne Osbourn of the John Innes Centre, whilst studying a natural antimicrobial compound produced by oats, found that the genes that made this compound were in fact clustered. Her group used the 'signature' of these genes' arrangement to search for other potential clusters, in the model plant Arabidopsis.
Publishing in the journal Proceeding of the National Academy of Sciences, Professor Osbourn and her colleagues at Stanford University and France's Institut National de la Recherche Agronomique (INRA) have now discovered the second of two gene clusters, both producing triterpene compounds. This allows them to look for common features of the gene clusters, giving new insights into how these clusters evolve.
Bacterial operons swap relatively easily between species, but the Arabidopsis gene clusters didn't enter the plant's genomes by this route. Both of the clusters are found in 'dynamic' regions of the genome that are significantly enriched in transposable elements.
These areas act like 'evolutionary playgrounds' where recombinations happen more frequently, bringing together different genes. When the gene clusters produce compounds that are useful to the plant, for example in fighting off pests, natural selection favours these clusters.
Crucially, in both of the triterpene gene clusters found by the group, the clusters must be maintained as a whole. Losing one part of the cluster leads to the build up of toxic intermediates. This causes an evolutionary pressure to maintain the cluster as a whole, as this increases the chances of the all of the genes being inherited together.
Clustering also allows the genes to be controlled in a coordinated manner, and comparing the gene clusters gave the scientists hints of how this might happen. Both gene clusters show signs that they are regulated by the way the DNA molecule folds or unfolds into chromatin, whilst neighbouring genes outside the clusters don't. Furthermore, it appears that this level of coordinated gene expression has been acquired by the cluster after its assembly.
These insights into the way these gene clusters have evolved and function will be particularly valuable for efforts to fully exploit the potential of plants to produce valuable products.
The ever-growing amount of data being generated by genome sequencing projects can be explored further, to try to discover similar gene clusters. For genes that have already been discovered, this information on clustering genes will help in efforts to use synthetic biology to optimise the production of new drugs, herbicides and other plant products.
Reference: 'Formation of plant metabolic gene clusters within dynamic chromosomal regions' will be published online by PNAS in the week beginning August 29th 2011 doi: 10.1073/pnas.1109273108
Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.
NASA refutes drought-driven declines in plant productivity, global food security
Boston MA (SPX) Aug 30, 2011
A new, comprehensive study by an international team of scientists, including scientists at Boston University in the US and the Universities of Vicosa and Campinas in Brazil, has been published in the current issue of Science (August 26, 2011) refuting earlier alarmist claims that drought has induced a decline in global plant productivity during the past decade and posed a threat to global food s ... read more
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2011 - Space Media Network. AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement|