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. 1986 Jun;81(2):663–668. doi: 10.1104/pp.81.2.663

Photosynthetic Induction in a C4 Dicot, Flaveria trinervia1

I. Initial Products of 14CO2 Assimilation and Levels of Whole Leaf C4 Metabolites

Brandon D Moore 1,2, Gerald E Edwards 1,2
PMCID: PMC1075395  PMID: 16664874

Abstract

Labeling patterns from 14CO2 pulses to leaves and whole leaf metabolite contents were examined during photosynthetic induction in Flaveria trinervia, a C4 dicot of the NADP-malic enzyme subgroup. During the first one to two minutes of illumination, malate was the primary initial product of 14CO2 assimiltion (about 77% of total 14C 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 14CO2 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 C4 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 C4 photosynthesis.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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