Frugal with Phosphorus

To conserve the scarcely available phosphorus in Western Australian soils, Banksia plants cut way back on some of the most phosphorus demanding biological processes. Nucleic acids, DNA and RNA, can bind up as much as 50% of the phosphorus in plant cells. Seen as a place to make cutbacks, Banksia does not produce nearly as much ribosomal RNA as do other plants. Since ribosomes are an integral part of protein production, the plant grows very slowly. Another trick to minimize the great need for phosphorus when new leaves are forming is to focus first on the formation of the leaf then afterward on formation of the photosynthetic apparatus, rather than doing both at the same time as is done in most plants. Banksia roots are extremely efficient at extracting phosphorus from the soil, but are ill equipped at avoiding uptake of too much when it is available, presumably because the trait was never needed during their evolution.

Plant Cell Environment, published online December 2013