Photosynthetic induction in a C/sub 4/, Flaveria trinervia. I. Initial products of /sup 14/CO/sub 2/ assimilation and levels of whole leaf C/sub 4/ metabolites

Journal Article · Sun Jun 01 00:00:00 EDT 1986 · Plant Physiol.; (United States)

OSTI ID:6990252

Moore, B D; Edwards, G E

Labeling patterns from /sup 14/CO/sub 2/ pulses to leaves and whole leaf metabolite contents were examined during photosynthetic induction in Flaveria trinervia, a C/sub 4/ dicot of the NADP-malic enzyme subgroup. During the first one to two minutes of illumination, malate was the primary initial product of /sup 14/CO/sub 2/ assimilation (about 77% of total /sup 14/C incorporated). After about 5 minutes of illumination, the proportion of initial label to aspartate increased from 16 to 66%, and then gradually declined during the following 7 to 10 minutes of illumination. Nutrition experiments showed that the increase in /sup 14/CO/sub 2/ partitioning to aspartate was delayed about 2.5 minutes in plants grown with limiting N, and was highly dampened in plants previously treated 10 to 12 days with ammonia as the sole N source. Measurements of C/sub 4/ leaf metabolites revealed several transients in metabolite pools during the first few minutes of illumination, and subsequently, more gradual adjustments in pool sizes. These include a large initial decrease in malate (about 1.6 micromoles per milligram chlorophyll) and a small initial decrease in pyruvate. There was a transient increase in alanine levels after 1 minute of illumination, which was followed by a gradual, prolonged decrease during the remainder of the induction period. Total leaf aspartate decreased initially, but temporarily doubled in amount between 5 and 10 minutes of illumination (after its surge as a primary product). These results are discussed in terms of a plausible sequence of metabolic events which lead to the formation of the intercellular metabolite gradients required in C/sub 4/ photosynthesis.

• Research Organization: Washington State Univ., Pullman
• OSTI ID: 6990252
• Journal Information: Plant Physiol.; (United States), Vol. 81:2
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
C4 SPECIES
CARBON DIOXIDE FIXATION
PHOTOSYNTHESIS
ALANINES
ASPARTIC ACID
BIOLOGICAL PATHWAYS
CARBON 14 COMPOUNDS
LEAVES
METABOLISM
METABOLITES
NUTRITION
PLANTS
TRACER TECHNIQUES
AMINO ACIDS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
SYNTHESIS
551001* - Physiological Systems- Tracer Techniques