Abstract
For the past 50 years there has been rapid warming in the maritime Antarctic(1-3), with concurrent, and probably temperature-mediated, proliferation of the two native plants, Antarctic pearlwort (Colobanthus quitensis) and especially Antarctic hair grass (Deschampsia antarctica)(4-10). In many terrestrial ecosystems at high latitudes, nitrogen (N) supply regulates primary productivity(11-13). Although the predominant view is that only inorganic and amino acid N are important sources of N for angiosperms, most N enters soil as protein. Maritime Antarctic soils have large stocks of proteinaceous N, which is released slowly as decomposition is limited by low temperatures. Consequently, an ability to acquire N at an early stage of availability is key to the success of photosynthetic organisms. Here we show that D. antarctica can acquire N through its roots as short peptides, produced at an early stage of protein decomposition, acquiring N over three times faster than as amino acid, nitrate or ammonium, and more than 160 times faster than the mosses with which it competes. Efficient acquisition of the N released in faster decomposition of soil organic matter as temperatures rise(14) may give D. antarctica an advantage over competing mosses that has facilitated its recent proliferation in the maritime Antarctic.
