Regulation of GmNRT2 expression and nitrate transport activity in roots of soybean (Glycine max)

Planta. 1998 Sep;206(1):44-52. doi: 10.1007/s004250050372.

Abstract

A full-length cDNA, GmNRT2, encoding a putative high-affinity nitrate transporter was isolated from a Glycine max (L.) root cDNA library and sequenced. The deduced GmNRT2 protein is 530 amino acids in length and contains 12 putative membrane-spanning domains and a long, hydrophilic C-terminal domain. GmNRT2 is related to high-affinity nitrate transporters in the eukaryotes Chlamydomonas reinhardtii and Aspergillus nidulans, and to putative high-affinity nitrate transporters in barley and tobacco. Southern blot analysis indicated that GmNRT2 is part of a small, multigene family in soybean. Expression of GmNRT2 in roots was regulated by the type of nitrogen source provided to plants: GmNRT2 mRNA levels were barely detectable in ammonium-grown plants, higher in nitrogen-deprived plants, and highest in nitrate-grown plants. Induction of GmNRT2 mRNA levels in roots occurred within 1 h after exposure of plants to nitrate. Nitrate induction of GmNRT2 mRNA levels was accompanied by a fourfold increase in net nitrate uptake by soybean roots at 100 microM external nitrate. The molecular and physiological evidence indicates that GmNRT2 is probably a high-affinity nitrate transporter involved in nitrate uptake by soybean roots.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Anion Transport Proteins*
  • Base Sequence
  • Biological Transport
  • Carrier Proteins / genetics*
  • Carrier Proteins / metabolism
  • DNA, Complementary
  • DNA, Plant
  • Gene Expression Regulation, Plant*
  • Molecular Sequence Data
  • Multigene Family
  • Nitrates / metabolism*
  • Plant Proteins / genetics*
  • Plant Proteins / metabolism
  • Plant Roots / metabolism
  • RNA, Messenger
  • Sequence Homology, Amino Acid
  • Soybean Proteins*
  • Soybeans / genetics*

Substances

  • Anion Transport Proteins
  • Carrier Proteins
  • DNA, Complementary
  • DNA, Plant
  • Nitrates
  • Plant Proteins
  • RNA, Messenger
  • Soybean Proteins
  • nitrate transporters

Associated data

  • GENBANK/AF047718