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Effects of growth light and nitrogen nutrition on the organization of the photosynthetic apparatus in leaves of a C 4 plant, Amaranthus cruentus
Author(s) -
TAZOE YOUSHI,
NOGUCHI KO,
TERASHIMA ICHIRO
Publication year - 2006
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2005.01453.x
Subject(s) - amaranthus cruentus , photosynthesis , rubisco , phosphoenolpyruvate carboxylase , chlorophyll , biology , botany , photosynthetic capacity , dry matter , horticulture , agronomy , amaranth
ABSTRACT Properties of C 4 photosynthesis were examined in Amaranthus cruentus L. (NAD‐malic enzyme (ME) subtype, dicot) grown under different light and nitrogen (N) conditions, from the viewpoint of N investment into their photosynthetic components. In low‐light (LL) leaves, chlorophyll content per leaf area was greater and chlorophyll a / b ratio was lower than in high‐light (HL) leaves. These indicate that LL leaves invest more N into their light‐harvesting systems. However, this N investment did not contribute to the increase in the quantum yield of photosynthesis on the incident photon flux density (PFD) basis ( Q i ) in LL leaves. N allocation to ribulose 1,5‐bisphosphate carboxylase/oxygenase (Rubisco) was significantly higher in HL‐high N (HN) leaves than in other leaves. On the other hand, N allocation to C 4 enzymes [phospho enol pyruvate carboxylase (PEPC) and pyruvate P i dikinase (PPDK)] was unaffected by the growth conditions. Maximum photosynthetic rates ( P max ) per Rubisco content were similar irrespective of the growth light treatments. Carbon isotope ratios ( δ 13 C) in the leaf dry matter were more negative in LL leaves than in HL leaves (LL = −19.3‰, HL = −16.0‰) and independent of leaf N. Vein density was highest in HL‐HN leaves, and leaf thickness was unaffected by the growth light treatments. From these results, we conclude that A. cruentus leaves would not acclimate efficiently to low growth light.