Functional Significance of Different Pathways of CO2 Fixation in Photosynthesis

Osmond, C. B.; Winter, Klaus; Ziegler, H.

doi:10.1007/978-3-642-68150-9_16

Cited by 222 publications

(179 citation statements)

References 198 publications

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“…However, there is no a priori reason to expect a greater tolerance of severe desiccation in C 4 than C 3 species [104]. In fact, recent comparative analyses of closely related C 3 and C 4 PACMAD grasses suggests the converse; that the C 4 photosynthetic system may be more prone to greater metabolic inhibition under chronic and severe drought events.…”

Section: Metabolic Limitation Of Photosynthesis During Severe Droughtmentioning

confidence: 99%

Evolution of C ₄ plants: a new hypothesis for an interaction of CO ₂ and water relations mediated by plant hydraulics

Osborne

Sack²

2012

Phil. Trans. R. Soc. B

181

193

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C 4 photosynthesis has evolved more than 60 times as a carbon-concentrating mechanism to augment the ancestral C 3 photosynthetic pathway. The rate and the efficiency of photosynthesis are greater in the C 4 than C 3 type under atmospheric CO 2 depletion, high light and temperature, suggesting these factors as important selective agents. This hypothesis is consistent with comparative analyses of grasses, which indicate repeated evolutionary transitions from shaded forest to open habitats. However, such environmental transitions also impact strongly on plant -water relations. We hypothesize that excessive demand for water transport associated with low CO 2 , high light and temperature would have selected for C 4 photosynthesis not only to increase the efficiency and rate of photosynthesis, but also as a water-conserving mechanism. Our proposal is supported by evidence from the literature and physiological models. The C 4 pathway allows high rates of photosynthesis at low stomatal conductance, even given low atmospheric CO 2 . The resultant decrease in transpiration protects the hydraulic system, allowing stomata to remain open and photosynthesis to be sustained for longer under drying atmospheric and soil conditions. The evolution of C 4 photosynthesis therefore simultaneously improved plant carbon and water relations, conferring strong benefits as atmospheric CO 2 declined and ecological demand for water rose.

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Section: Metabolic Limitation Of Photosynthesis During Severe Droughtmentioning

confidence: 99%

Evolution of C ₄ plants: a new hypothesis for an interaction of CO ₂ and water relations mediated by plant hydraulics

Osborne

Sack²

2012

Phil. Trans. R. Soc. B

181

193

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“…For decades, the occurrence of crassulacean acid metabolism (CAM) was associated primarily with succulent and shrub-like plants from arid habitats (Osmond et al 1982). Particularly the work of Nuembergk (1960), Coutinho (1969) and Winter (1985) initiated a change in our perception of a "typical" CAM plant.…”

Section: Introductionmentioning

confidence: 99%

How prevalent is crassulacean acid metabolism among vascular epiphytes?

Zotz

2004

Oecologia

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The occurrence of crassulacean acid metabolism (CAM) in the epiphyte community of a lowland forest of the Atlantic slope of Panama was investigated. I hypothesized that CAM is mostly found in orchids, of which many species are relatively small and/or rare. Thus, the relative proportion of species with CAM should not be a good indicator for the prevalence of this photosynthetic pathway in a community when expressed on an individual or a biomass basis. In 0.4 ha of forest, 103 species of vascular epiphytes with 13,099 individuals were found. As judged from the C isotope ratios and the absence of Kranz anatomy, CAM was detected in 20 species (19.4% of the total), which were members of the families Orchidaceae, Bromeliaceae, and Cactaceae. As predicted, the contribution of CAM epiphytes to the total number of individuals and to total biomass (69.6 kg ha"') was considerably lower (3.6% or 466 individuals and, respectively, 3.0% or 2.1 kg ha"').

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“…High variability among the plants precluded a greater degree of statistical significance. Substantial amounts of morning (Phase II, see Osmond, 1978) and afternoon (Phase IV) C0 2 uptake were also observed in the mature sporophytes, which is not uncommon in some CAM species. As expected in obligate CAM plants under well-watered conditions, the amount of malic acid decarboxylated during the day (presumed equal to the amount accumulated during the previous night) was not significantly different (P > 0.20) from the amount of C0 2 absorbed throughout the night (Table 1).…”

Section: Resultsmentioning

confidence: 79%

C₃ photosynthesis in the gametophyte of the epiphytic CAM fern Pyrrosia longifolia (Polypodiaceae)

Martin

Allen

Haufler

1995

American J of Botany

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Sporophytes of some epiphytic species in the fern genus Pyrrosia exhibit Crassulacean acid metabolism (CAM), generally considered to be a derived physiological response to xeric habitats. Because these species alternate between independent sporophytic and gametophytic generations yet only the sporophyte has been characterized physiologically, experiments were conducted to determine the photosynthetic pathways present in mature sporophytes, immature sporophytes, and gametophytes of Pyrrosia longifolia. Diurnal C0 2 exchange and malic acid fluctuations demonstrated that although the mature sporophytes exhibited CAM, only C 3 photosynthesis occurred in the gametophytes and young sporophytes. Consideration of the above results and those from previous studies, as well as the life cycle of ferns, indicates that the induction of CAM probably occurs at a certain developmental stage of the sporophyte and/or following exposure to stress. Elucidation of the precise mechanisms underlying this C^-CAM transition awaits further research.

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Functional Significance of Different Pathways of CO2 Fixation in Photosynthesis

Cited by 222 publications

References 198 publications

Evolution of C ₄ plants: a new hypothesis for an interaction of CO ₂ and water relations mediated by plant hydraulics

Evolution of C ₄ plants: a new hypothesis for an interaction of CO ₂ and water relations mediated by plant hydraulics

How prevalent is crassulacean acid metabolism among vascular epiphytes?

C₃ photosynthesis in the gametophyte of the epiphytic CAM fern Pyrrosia longifolia (Polypodiaceae)

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Functional Significance of Different Pathways of CO2 Fixation in Photosynthesis

Cited by 222 publications

References 198 publications

Evolution of C 4 plants: a new hypothesis for an interaction of CO 2 and water relations mediated by plant hydraulics

Evolution of C 4 plants: a new hypothesis for an interaction of CO 2 and water relations mediated by plant hydraulics

How prevalent is crassulacean acid metabolism among vascular epiphytes?

C3 photosynthesis in the gametophyte of the epiphytic CAM fern Pyrrosia longifolia (Polypodiaceae)

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Evolution of C ₄ plants: a new hypothesis for an interaction of CO ₂ and water relations mediated by plant hydraulics

Evolution of C ₄ plants: a new hypothesis for an interaction of CO ₂ and water relations mediated by plant hydraulics

C₃ photosynthesis in the gametophyte of the epiphytic CAM fern Pyrrosia longifolia (Polypodiaceae)