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CAM ‐physiology and carbon gain of the orchid Phalaenopsis in response to light intensity, light integral and CO 2
Author(s) -
Hogewoning Sander W.,
Boogaart Stefan A.J.,
Tongerlo Evelien,
Trouwborst Govert
Publication year - 2021
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/pce.13960
Subject(s) - crassulacean acid metabolism , photosynthesis , carboxylation , light intensity , diel vertical migration , rubisco , decarboxylation , botany , phalaenopsis , phosphoenolpyruvate carboxylase , carbon fibers , carbon dioxide , chemistry , biology , biochemistry , ecology , materials science , physics , catalysis , optics , composite number , composite material
The regulation of photosynthesis and carbon gain of crassulacean acid metabolism (CAM) plants has not yet been disclosed to the extent of C3‐plants. In this study, the tropical epiphyte Phalaenopsis cv. “Sacramento” was subjected to different lighting regimes. Photosynthesis and biochemical measuring techniques were used to address four specific questions: (1) the response of malate decarboxylation to light intensity, (2) the malate carboxylation pathway in phase IV, (3) the response of diel carbon gain to the light integral and (4) the response of diel carbon gain to CO 2 . The four CAM‐phases were clearly discernable. The length of phase III and the malate decarboxylation rate responded directly to light intensity. In phase IV, CO 2 was initially mainly carboxylated via Rubisco. However, at daylength of 16 h, specifically beyond ±12 h, it was mainly phospho enol pyruvate carboxylase (PEP‐C) carboxylating CO 2 . Diel carbon gain appeared to be controlled by the light integral during phase III rather than the total daily light integral. Elevated CO 2 further enhanced carbon gain both in phase IV and phase I. This establishes that neither malate storage capacity, nor availability of PEP as substrate for nocturnal CO 2 carboxylation were limiting factors for carbon gain enhancement. These results advance our understanding of CAM‐plants and are also of practical importance for growers.