Article

The Nitrogen Use Efficiency of C3 and C4 Plants III. Leaf Nitrogen Effects on the Activity of Carboxylating Enzymes in Chenopodium album (L.) and Amaranthus retroflexus (L.)

Department of Botany, University of California, Davis, California 95616.
Plant physiology (Impact Factor: 6.84). 11/1987; 85(2):355-9. DOI: 10.1104/pp.85.2.355
Source: PubMed

ABSTRACT

The relationships between leaf nitrogen content per unit area (N(a)) and (a) the initial slope of the photosynthetic CO(2) response curve, (b) activity and amount of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and phosphoenolpyruvate carboxylase (PEPC), and (c) chlorophyll content were studied in the ecologically similar weeds Chenopodium album (C(3)) and Amaranthus retroflexus (C(4)). In both species, all parameters were linearly dependent upon leaf N(a). The dependence of the initial slope of the CO(2) response of photosynthesis on N(a) was four times greater in A. retroflexus than in C. album. At equivalent leaf N(a) contents, C. album had 1.5 to 2.6 times more CO(2) saturated Rubisco activity than A. retroflexus. At equal assimilation capacities, C. album had four times the Rubisco activity as A. retroflexus. In A. retroflexus, a one to one ratio between Rubisco activity and photosynthesis was observed, whereas in C. album, the CO(2) saturated Rubisco activity was three to four times the corresponding photosynthetic rate. The ratio of PEPC to Rubisco activity in A. retroflexus ranged from four at low N(a) to seven at high N(a). The fraction of organic N invested in carboxylation enzymes increased with increased N(a) in both species. The fraction of N invested in Rubisco ranged from 10 to 27% in C. album. In A. retroflexus, the fraction of N(a) invested in Rubisco ranged from 5 to 9% and the fraction invested in PEPC ranged from 2 to 5%.

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    • "The SPAD measure is mainly influenced by absorbancetransmittance red light of 650 nm by the leaf chl conc (Markwell et al., 1995). In addition, Rubisco alone shares 30%, but Rubisco, PEPC and pyruvate orthophosphate dikinase shares 50% of the total soluble proteins in leaves of C4 plant species (Sugiyama et al., 1984; Sage et al., 1987; Makino et al., 2003). But, most of the hybrids have parallel dynamics of N and chl concentration in the leaves except in long-stay-green genotypes (Thomas et al., 2002; Ho¨rtensteiner and Feller, 2002; Ho¨rtensteiner, 2006). "
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    • "Photosynthetic proteins encompass the majority of leaf nitrogen—for example, Rubisco (EC 4.1.1.39) typically accounts for between 10% and 30% of leaf nitrogen content but can account for up to 50% of leaf nitrogen content (Ellis, 1979; Sage et al., 1987; Evans, 1989). Through Rubisco, carbon source activity is directly connected with leaf nitrogen sink activity, providing one way in which source and sink activity are intrinsically coordinated. "
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    • "hesis capacity is also more profound in C 3 species than in C 4 species ( Morgan et al . , 2001 ; Duarte et al . , 2014 ) , due in part to the N dilution , possibly because C 3 plants need to invest more N from the leaf into Rubisco , relative to the C 4 species , so that the former may easily undergo more severe N dilution under CO 2 enrichment ( Sage et al . , 1987 ; Yin , 2002 ; Luo et al . , 2004 ; Sage , 2004 ) , with no CCM ( von Caemmerer and Furbank , 2003 ) ."
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