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Control of Nitrate Uptake by Phloem‐Translocated Glutamine in Zea mays L. Seedlings
Author(s) -
Pal'oveBalang P.,
Mistrík I.
Publication year - 2002
Publication title -
plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 1435-8603
DOI - 10.1055/s-2002-34123
Subject(s) - phloem , biology , glutamine , zea mays , nitrate , shoot , amino acid , botany , horticulture , biochemistry , agronomy , ecology
Abstract: The putative role of glutamine, exported from leaves to roots, as a negative feedback signal for nitrate uptake was investigated in Zea mays L. seedlings. Glutamine (Gln) was supplied by immersion of the tip‐cut leaves in a concentrated solution. Nitrate (NO 3 − ) uptake was measured by its depletion in amino acid‐free medium. The treatment with Gln resulted in a strong inhibition of nitrate uptake rate, accompanied by a significant enrichment of amino compounds in root tissue. The effect of N‐availability on NO 3 − uptake was determined in split‐root cultures. The plants were subjected to complete or localized N supply. Inducible NO 3 − uptake systems were also induced in N‐deprived roots when the opposite side of the root system was supplied with KNO 3 . The inhibitory effect of Gln was unaffected by localized N supply on one side of the split‐root. The potential role of Gln in the shoot‐to‐root control of NO 3 − uptake is discussed.