PT  - JOURNAL ARTICLE
AU  - Sanliang Gu
AU  - Porter B. Lombard
AU  - Steven F. Price
TI  - Inflorescence Necrosis Induced from Ammonium Incubation and Deterred by α-Keto-Glutarate and Ammonium Assimilation in Pinot noir Grapevines
AID  - 10.5344/ajev.1994.45.2.155
DP  - 1994 Jan 01
TA  - American Journal of Enology and Viticulture
PG  - 155--160
VI  - 45
IP  - 2
4099  - http://www.ajevonline.org/content/45/2/155.short
4100  - http://www.ajevonline.org/content/45/2/155.full
SO  - Am J Enol Vitic.1994 Jan 01; 45
AB  - Inflorescence necrosis (IN) and increased tissue NH4+ occurred after incubating single-node, field-grown, Pinot noir grape (Vitis vinifera L.) cuttings with one leaf and cluster in 120 mM or higher NH4+ solutions of NH4NO3 or (NH4)2SO4. Incubation with solutions of NO3-, SO4=, and K+ at the same concentrations did not induce IN. The addition of 80 mM KG, a substrate for ammonium assimilation, to an incubation solution containing 160 mM NH4+ deterred IN and lowered flower or fruit NH4+ to near control levels. The presence of glutamine synthetase/ glutamate synthase (GS/GOGAT) pathway of ammonium assimilation was detected in flowers, fruit, and pedicels, but not in rachis of cuttings treated with GS/GOGAT inhibitors: i.e., 10 mM MSX (a GS inhibitor) or 5 mM AS (a GOGAT inhibitor). Glutamate dehydrogenase (GDH) is not involved in ammonium assimilation and detoxification in grape inflorescence. Chemical names used: α-keto-glutarate (KG), methionine sulfoximine (MSX), azaserine (AS).