Uptake and metabolism of (14C)-aspartate by developing kernels of maize (Zea mays L. )

Conference · Tue May 01 04:00:00 EDT 1990 · Plant Physiology, Supplement; (USA)

OSTI ID:5627750

Muhitch, M J ^[1]

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1. USDA, Peoria, IL (USA)

Pulse-chase experiments were performed to determine the metabolic fate of (14C)-aspartate in the pedicel region and subsequent uptake into the endosperm. Kernels were removed from the cob, leaving the pedicel attached but removing glumes, palea, and lemma. The basal tips were incubated in (14C)-aspartate for 0.5 h, followed by a 2 h chase period with unlabeled aspartate. In contrast to a previous study in which 70% of the 14C from aspartate was recovered in the organic acid fraction (Lyznik, et al., Phytochemistry 24: 425, 1985), only 20 to 25% of the radioactivity found in the 2 h chase period. While a small amount of the 14C transiently appeared in alanine at the beginning of the chase period, the most heavily labeled non-fed amino acid was glutamine, which accounted for 21% of the radioactivity within the pedicel amino acid fraction by 0.5 h into the chase period. There was no evidence for asparagine synthesis within the pedicel region of the kernel. 14C recovered from the endosperm in the form of amino acids were aspartate (60%), glutamine (20%), glutamate (15%), and alanine (5%). These results suggest that some of the maternally supplied amino acids undergo metabolic conversion to other amino acids before being taken up by the endosperm.

• OSTI ID: 5627750
• Report Number(s): CONF-9007196--
• Conference Information: Journal Name: Plant Physiology, Supplement; (USA) Journal Volume: 93:1
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
ASPARTIC ACID
BIOLOGICAL PATHWAYS
CARBON 14 COMPOUNDS
CARBOXYLIC ACIDS
CEREALS
GRAMINEAE
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LILIOPSIDA
MAGNOLIOPHYTA
MAIZE
METABOLISM
ORGANIC ACIDS
ORGANIC COMPOUNDS
PLANTS
TRACER TECHNIQUES
UPTAKE