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- Title
Nitrogen uptake in relation to excess supply and its effects on the lichensEvernia prunastri(L.) Ach andXanthoria parietina(L.) Th. Fr.
- Authors
Gaio-Oliveira, Gisela; Dahlman, Lena; Palmqvist, Kristin; Martins-Loução, Maria Amélia; Máguas, Cristina
- Abstract
The aim of this study was to compare the physiological responses to increased nitrogen (N) supply between the nitrophytic lichenXanthoria parietina(L.) Th. Fr. and the acidophytic lichenEvernia prunastri(L.) Ach. The two lichens were exposed to a weekly dosage of 0.05, 0.1, 0.2, 0.6 or 2.4 g N m-2 for 2 months, administered as NH4NO3 dissolved in artificial rainwater (1 l m-2). After the treatments, in vivo chlorophyllafluorescence was determined to assess vitality; concentrations of total N, ammonium, nitrate and dominant amino acids, including glutamate, glutamine and arginine, were quantified in order to follow changes in N status; and the polyols ribitol, arabitol and mannitol were quantified to follow changes in the lichens’ carbon (C) status. The uptake of N was quantified by labelling the fertiliser with15N in the ammonium position; chlorophyllawas used as an indirect marker for algal activity, and ergosterol as an indirect marker of fungal activity. Nitrogen uptake was higher inE. prunastrithan inX. parietina, although the latter species may have used the mannitol reserves to obtain C skeletons and energy for N assimilation. Chlorophyllaand ergosterol concentrations remained unaltered inX. parietinairrespective of N dosage while ergosterol decreased with increasing N uptake inE. prunastri. The latter species had accumulated a large pool of ammonium at the highest N dosage, whilst inX. parietinaa significant nitrate pool was instead observed. Taken together, these short-term responses to high N supply observed in the two lichens, and the differences between them, can partly explain the higher tolerance ofX. parietinatowards increased atmospheric N levels.
- Subjects
PLANT physiology; LICHENS; XANTHORIA; NITROGEN; AMMONIUM; PLANT assimilation
- Publication
Planta: An International Journal of Plant Biology, 2005, Vol 220, Issue 5, p794
- ISSN
0032-0935
- Publication type
Article
- DOI
10.1007/s00425-004-1396-1