Suberin is a polyester polymer located in the cell walls of seed and root systems of terrestrial plants. It acts as a protective barrier against pathogenic organisms or harmful substances, while facilitating the intake of water and nutrients. Suberin is also reported to have an important role in enabling plants to tolerate environmental stresses, such as dry or high saline soils. Using a model plant called Arabidopsis, scientists from the Brookhaven National Laboratory (United States) found that an enzyme called, hydroxyacid hydroxycinnamoyltransferase (HHT), is an important enzyme for suberin biosynthesis. Suberin-deficient plants were observed to be "much more permeable to salt in solution than their wild-type counterparts", indicating that "suberin plays an important role in the adaptation of plants to their terrestrial habitats". According to Brookhaven biologist Chang-Jun Liu, "identifying the key biosynthetic enzymes and understanding suberin production may be particularly important for growing plants on the marginal soils that have been proposed for use in farming bioenergy crops". Enabling biofuel crops to thrive in marginal soils can help ensure the use of productive, fertile lands for food production. Another interesting finding of the study showed that suberin polyphenolics share the same biosynthetic precursors with lignin (the tight chemical wrapping surrounding cellulose fibers in lignocellulosic biomass), but both are produced by different enzymes. This could eventually lead to the development of tailor-made bioenergy crops which are easier to digest ("pretreat") and process into biofuels, while simultaneously "redirecting photosynthetic carbon to improve carbon-sequestration efforts". The complete study is published in the Proceedings of the National Academy of Sciences (PNAS) (URL above)..