A new genetic road map of tobacco has been used to successfully identify and clone two mutated genes associated with how efficiently the plants used nitrogen – a discovery that could one day help reduce the need for nitrogen-based fertilisers in growing crops.
These same genes could also play a role in helping to reduce the levels of some carcinogenic compounds in cigarette smoke.
The overuse of nitrogen-based fertilisers on crops can lead to an excess of nitrate in the environment, which can in turn lead to water acidification and eutrophication, in addition to nutrients leaching from the soil. This can cause reductions in biodiversity and crop productivity, as well as having negative impacts on both animal and human health. In the case of tobacco, inefficient metabolism of nitrogen by the plant can lead to high concentrations of some nitrogen-based compounds in the leaf, the presence of which lead to the formation of certain tobacco-specific toxicants in smoke.
Scientists are working together to develop a new genetic roadmap of the tobacco genome (Nicotiana tabacum). This road map lays out the position of (or “anchors”) 64% of the tobacco genome, compared to just 20% in previous attempts. To anchor the genetic code, the researchers used a new technique known as optical mapping. This involves taking a fingerprint of the genome — marking specific sequence patterns in very long sequences of unknown DNA — to create a barcode of DNA fragments. This has enabled much more of the genome to be anchored to tobacco chromosomes compared to previous assemblies. (ANI)
