Nitrogen reserve status affects the dynamics of nitrogen remobilization and mineral nitrogen uptake during recovery of contrasting cultivars of Lolium perenne from defoliation

S. Louahlia, J. H. Macduff, A. Ourry, M. Humphreys, J. Boucaud

Research output: Contribution to journalArticlepeer-review

46 Citations (SciVal)

Abstract

Nitrogen (N) allocated to leaf growth in forage grasses and legumes following severe defoliation is predominately mobilized from the remaining root and leaf sheath tissues, since both N uptake from the soil and N 2 fixation are severely down-regulated for several days. The hypothesis that a low N reserve status at the time of defoliation limits N remobilization and leaf regrowth was tested with contrasting cultivars of Lolium perenne (cvs Abetelan and Cariad) in flowing solution culture. Plants were grown under 'high' or 'low' (uptake of N decreased by 50 %) regimes of N supply for 10 d before a single severe defoliation. Labelling with 15N was used to assess the importance of N reserves, including putative vegetative storage proteins, relative to N translocated from concurrent uptake, as a source of leaf N during regrowth. Leaf regrowth, N uptake and N mobilization were all affected by previous N supply. Low plant N status at the time of defoliation increased regrowth dry weight of 'Aberelan' by 10 % and translocation of N absorbed from the medium by 23 %, while mobilization of N reserves was decreased by 56%. On the contrary, regrowth dry weight of 'Cariad' was decreased by 23%, and translocation of N absorbed by 21% in low plant N status, compared with high plant N status. Concentrations of soluble protein in roots and remaining leaf sheaths decreased after defoliation in plants only under optimal N supply. Analysis of soluble proteins in sheath material by SDS-PAGE suggested that three polypeptides (55, 36.6 and 24 kDa) might function as vegetative storage proteins, although they were of low abundance in plants, subjected to monthly harvests, grown in controlled conditions and in the field. The apparent antagonism between uptake of NH 4 + or NO 3 - by roots and mobilization of N reserves is discussed together with evidence for functional vegetative storage proteins in L. perenne.

Original languageEnglish
Pages (from-to)451-462
Number of pages12
JournalNew Phytologist
Volume142
Issue number3
DOIs
Publication statusPublished - 01 Jun 1999

Keywords

  • ammonium
  • defoliation
  • Poaceae
  • Lolium perenne
  • nitrate
  • vegetative storage proteins
  • fructans
  • Ammonium
  • Vegetative storage proteins
  • Nitrate
  • Defoliation
  • Fructans

Fingerprint

Dive into the research topics of 'Nitrogen reserve status affects the dynamics of nitrogen remobilization and mineral nitrogen uptake during recovery of contrasting cultivars of Lolium perenne from defoliation'. Together they form a unique fingerprint.

Cite this