Nitrogen (N) is a fundamental element for plant growth and development. Traditionally, research of plant nitrogen uptake and metabolism has been aimed at the inorganic nitrogen sources nitrate and ammonium. An accumulating amount of research has, however, shown that organic nitrogen sources, such as amino acids, may be of large importance for plant nutrition
This research project is primarily concerned with the importance of organic nitrogen for plant nutrition and ecosystem composition in boreal forests. In this project, we have shown that a wide range boreal forest species are capable of taking up amino acids at rates comparable to the uptake of ammonium and nitrate. We have also been able to show that plants, in varying amounts, are capable of rapidly acquiring nitrogen from complex organic compounds, such as protein.

After showing that plants are well capable of competing for organic nitrogen sources, future research will primarily be concerned with elucidating the importance of organic nitrogen for plant N nutrition and ecosystem composition. In other words – how much of plant N comes from the uptake of organic compounds as compared to inorganic compounds, and how do differing abilities to take up organic N affect the species composition in our forests?

Now that can´t be too hard – can it

In order to follow N uptake and metabolism, we use a combination of chromatographic and mass spectrometric methods, where the use of compounds labeled with stable isotopes play a key role. Gas as well as liquid chromatography are frequently used, as is ion trap mass spectrometry and isotope ratio mass spectrometry (IRMS). Using these techniques, we routinely analyse and quantify a wide array of organic compounds related to plant structure and metabolism, although we are mainly focused on simple N compounds, such as amino acids and amino sugars.This project is performed under supervision (and funding) by Torgny Näsholm. Part of the work is done in collaboration with Prof. Peter Högberg at the Dept. of Forest Ecology (SLU, Umeå). I am also currently doing studies on nitrogen relations in lichens together with Lena Dahlman at Umeå University. Avid help is also continuously supplemented by the mass spec. group here at UPSC. 

Näsholm and Persson () Plant acquisition of organic nitrogen in boreal forests. Physiol Plant 111: 419-426
Persson and Näsholm () A GC-MS method for determination of amino acid uptake by plants. Physiol Plant 113: 352-358

Persson and Näsholm () Amino acid uptake: a widespread ability among boreal forest plants. Ecol Lett 4: 434-438