Carbohydrate partitioning in the leaves of Bromeliaceae performing C3 photosynthesis or Crassulacean acid metabolism

1998 ◽  
Vol 25 (3) ◽  
pp. 371 ◽  
Author(s):  
John T. Christopher ◽  
Joseph A. M. Holtum
Keyword(s):  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Soluble Sugars ◽  
Carbohydrate Accumulation ◽  
Carbohydrate Partitioning ◽  
C3 Species ◽  
C3 Photosynthesis ◽  
Cam Species

Carbohydrate accumulation was measured in the leaves of 11 speciesrepresenting the three subfamilies of Bromeliaceae. In the Tillandsioideae the C3 species Vriesea carinata Wawra accumulated starch and sucrose while the Crassulacean acid metabolism (CAM)species Tillandsia tricolor Schlechtendal & Chamissoaccumulated mainly starch. In the Pitcairnioideae the C3species Pitcairnia paniculata Ruiz & Pavon and two CAM species Dyckia sp. andFosterella schidosperma Barker accumulated sucrose butnot starch. Of six CAM species in the Bromelioideae, threeCryptanthus zonatus (Visiani) Beer,Neoregalia spectabilis Moore andPortea petropolitana Wawra accumulated starch but notsoluble sugars while three (Ananus comosus Linnaeus,Orthophytum vagans M.B. Foster andNidularium bilbergioides Schultes filius) accumulatedstarch as well as soluble sugars. Carbohydrate accumulation patterns weresimilar for species within each subfamily in that the Pitcairnioideae speciesdid not accumulate starch but accumulated sucrose while species from theTillandsioideae and Bromelioideae all accumulated starch (some alsoaccumulated soluble sugars). Carbohydrate accumulation patterns were notsimilar for C3 species versus CAM species from thedifferent subfamilies. These data suggest that variations in carbohydratebiochemistry resulting from different evolutionary histories have a greaterinfluence on carbohydrate accumulation patterns in CAM bromeliads than theconstraints of the CAM pathway itself.

Is a Low Internal Conductance to CO2 Diffusion a Consequence of Succulence in Plants with Crassulacean Acid Metabolism?

1997 ◽  
Vol 24 (6) ◽  
pp. 777 ◽  
Author(s):  
Kate Maxwell ◽  
Susanne von Caemmerer ◽  
John R. Evans
Keyword(s):  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Ambient Air ◽  
Co2 Assimilation ◽  
Co2 Partial Pressure ◽  
Co2 Diffusion ◽  
Internal Conductance ◽  
C3 Species ◽  
Cam Species ◽  
Transient Phases

Leaf internal conductance to CO2 (gi) from substomatal cavity to the carboxylation sites of Rubisco was measured in the leaf succulent CAM species, Kalanchoe daigremontiana Hamet et Perr. Measurements were made during Rubisco-mediated atmospheric C3 carboxylation in phase IV photosynthesis. Using simultaneous gas exchange and chlorophyll fluorescence techniques, internal conductance was calculated to be 0.05 mol m-2 s-1 bar-1 , when measured at both saturating and limiting light. This is one of the lowest recorded values for gi as compared to a range of C3 species with comparable Rubisco content and indicates a large diffusion limitation to atmospheric CO2 fixation through the C3 pathway in K. daigremontiana. In ambient air, CO2 partial pressure at the carboxylation sites of Rubisco was 109 µbar. Internal diffusion is limited by a thick leaf consisting of densely packed, succulent mesophyll with a small portion of airspace. We speculate that a low internal conductance to CO2 diffusion results from the compromise between a succulent mesophyll required for C4 acid storage and access for CO2 diffusion to both PEPC in the cytoplasm and Rubisco in the chloroplasts. Restricted diffusion of CO2 within the leaf makes CO2 assimilation less efficient during the transient phases of crassulacean acid metabolism.

Carbohydrate partitioning in crassulacean acid metabolism plants: reconciling potential conflicts of interest

2002 ◽  
Vol 29 (6) ◽  
pp. 707 ◽  
Author(s):  
Anne M. Borland ◽  
Antony N. Dodd
Keyword(s):  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Conflicts Of Interest ◽  
Critical Mass ◽  
Soluble Sugars ◽  
Carbon Budgets ◽  
Cam Plants ◽  
Carbohydrate Partitioning ◽  
Isotopic Signatures ◽  
High Level

This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001. The construction of diel leaf carbon budgets, together with analyses of the δ13C composition of biochemical fractions, was used to examine how crassulacean acid metabolism (CAM) plants adjust carbohydrate partitioning in response to shifting sink demands. For Mesembryanthemum crystallinum L., net carbon budgets indicated clear shifts in assimilate partitioning and in the relative proportions of day : night export as CAM was induced. Different patterns of carbohydrate partitioning in primary and axillary leaves of this species may reflect the different sink priorities of determinate and indeterminate growth. In primary leaves, the high level of diel starch turnover may be a strategy for ensuring production of a critical mass of juvenile tissue that poises the plant for CAM induction. In axillary leaves, the high day-night flux through soluble sugars may ensure ready availability of assimilates for export to reproductive sinks. Carbon isotope ratios were measured for various organic fractions isolated from leaves and fruits of two species of Clusia that differ in CAM expression. Similar and C3-like isotopic signatures were obtained for the structural material isolated from fruits of Clusia minor L. and Clusia rosea Jacq. The data suggest that the partitioning of C4- and C3-derived assimilates into discrete storage and transport pools of soluble sugars will ensure reproductive output, regardless of the level of CAM that is induced in these species.

Sucrose transport across the vacuolar membrane of Ananas comosus

2002 ◽  
Vol 29 (6) ◽  
pp. 717 ◽  
Author(s):  
Shelley R. McRae ◽  
John T. Christopher ◽  
J. Andrew C. Smith ◽  
Joseph A. M. Holtum
Keyword(s):  
Atpase Activity ◽  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
External Medium ◽  
Soluble Sugars ◽  
Sugar Transport ◽  
Phase Iii ◽  
Ananas Comosus ◽  
Sucrose Uptake ◽  
Sucrose Transport

This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001. In Ananas comosus L. (Merr.) (pineapple), a widely cultivated bromeliad that exhibits crassulacean acid metabolism (CAM), much of the carbohydrate synthesized during the daytime appears to accumulate as soluble sugars in the vacuole. To investigate the mechanism of sugar transport into the vacuole, microsomal extracts were prepared from deacidifying leaves harvested during Phase III of the CAM cycle. The vesicle preparations exhibited features expected for a fraction highly enriched in vacuolar membranes (tonoplast), i.e. the ATPase activity of 16 ±�2�nkat mg-1 protein was inhibited 96% by 50 mm KNO3, an inhibitor of vacuolar ATPases, and was only 7% inhibited by 100μm NaN3 plus 100μm Na3VO4, inhibitors of mitochondrial and plasma membrane ATPases, respectively. Further, the microsomal ATPase activity showed a pH optimum between 7.0 and 8.0, typical of a vacuolar ATPase. When presented with Mg-ATP, vesicles established H+ gradients that could be maintained for at least 25 min. The vesicles were able to take up [14C]sucrose from an external medium. Sucrose uptake exhibited saturable kinetics with an apparent Km of 50 m sucrose and apparent Vmax of 171 ± 5 pkat mg-1 protein. Sucrose uptake was not dependent upon, nor stimulated by, Mg-ATP, suggesting that the mechanism of sucrose transport into the vacuole in A. comosus does not involve H+-coupled cotransport. However, the initial rates of sucrose uptake from the external medium were stimulated when vesicles were preloaded with sucrose. This trans-stimulation is consistent with characteristics expected for a sucrose uniporter capable of operating in an exchange mode. It is proposed that the accumulation of glucose and fructose in leaf vacuoles of Ananas during the light period involves at least two steps - transport of sucrose into the vacuole by a mechanism exhibiting characteristics of a sucrose uniporter, followed by cleavage of sucrose by a vacuolar acid invertase to form glucose and fructose.

scholarly journals A perspective on crassulacean acid metabolism photosynthesis evolution of orchids on different continents: Dendrobium as a case study

2019 ◽  
Vol 70 (22) ◽  
pp. 6611-6619
Author(s):  
Ming-He Li ◽  
Ding-Kun Liu ◽  
Guo-Qiang Zhang ◽  
Hua Deng ◽  
Xiong-De Tu ◽  
...  
Keyword(s):  
Crassulacean Acid Metabolism ◽  
Middle Miocene ◽  
Acid Metabolism ◽  
Flowering Plants ◽  
Asian Clade ◽  
Wide Range ◽  
Cam Species ◽  
Climatic Cooling ◽  
Cam Photosynthesis

Abstract Members of the Orchidaceae, one of the largest families of flowering plants, evolved the crassulacean acid metabolism (CAM) photosynthesis strategy. It is thought that CAM triggers adaptive radiation into new niche spaces, yet very little is known about its origin and diversification on different continents. Here, we assess the prevalence of CAM in Dendrobium, which is one of the largest genera of flowering plants and found in a wide range of environments, from the high altitudes of the Himalayas to relatively arid habitats in Australia. Based on phylogenetic time trees, we estimated that CAM, as determined by δ 13C values less negative than –20.0‰, evolved independently at least eight times in Dendrobium. The oldest lineage appeared in the Asian clade during the middle Miocene, indicating the origin of CAM was associated with a pronounced climatic cooling that followed a period of aridity. Divergence of the four CAM lineages in the Asian clade appeared to be earlier than divergence of those in the Australasian clade. However, CAM species in the Asian clade are much less diverse (25.6%) than those in the Australasian clade (57.9%). These findings shed new light on CAM evolutionary history and the aridity levels of the paleoclimate on different continents.

scholarly journals Concerted anatomical change associated with crassulacean acid metabolism in the Bromeliaceae

2018 ◽  
Vol 45 (7) ◽  
pp. 681 ◽  
Author(s):  
Jamie Males
Keyword(s):  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Leaf Structure ◽  
Photosynthetic Pathway ◽  
Evolutionary Transitions ◽  
Strongly Coupled ◽  
Plant Ecophysiology ◽  
Evolutionary Changes ◽  
Cam Species ◽  
Analysis Of Variation

Crassulacean acid metabolism (CAM) is a celebrated example of convergent evolution in plant ecophysiology. However, many unanswered questions surround the relationships among CAM, anatomy and morphology during evolutionary transitions in photosynthetic pathway. An excellent group in which to explore these issues is the Bromeliaceae, a diverse monocot family from the Neotropics in which CAM has evolved multiple times. Progress in the resolution of phylogenetic relationships among the bromeliads is opening new and exciting opportunities to investigate how evolutionary changes in leaf structure has tracked, or perhaps preceded, photosynthetic innovation. This paper presents an analysis of variation in leaf anatomical parameters across 163 C3 and CAM bromeliad species, demonstrating a clear divergence in the fundamental aspects of leaf structure in association with the photosynthetic pathway. Most strikingly, the mean volume of chlorenchyma cells of CAM species is 22 times higher than that of C3 species. In two bromeliad subfamilies (Pitcairnioideae and Tillandsioideae), independent transitions from C3 to CAM are associated with increased cell succulence, whereas evolutionary trends in tissue thickness and leaf air space content differ between CAM origins. Overall, leaf anatomy is clearly and strongly coupled with the photosynthetic pathway in the Bromeliaceae, where the independent origins of CAM have involved significant anatomical restructuring.

scholarly journals Phosphoenolpyruvate carboxylase from pennywort (Umbilicus rupestris). Changes in properties after exposure to water stress

1984 ◽  
Vol 218 (2) ◽  
pp. 387-393 ◽  
Author(s):  
P P Daniel ◽  
J A Bryant ◽  
F I Woodward
Keyword(s):  
Water Stress ◽  
Phosphoenolpyruvate Carboxylase ◽  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Marked Decrease ◽  
Cam Plants ◽  
Allosteric Inhibitor ◽  
Allosteric Effector ◽  
Incomplete Form ◽  
C3 Photosynthesis

Umbilicus rupestris (pennywort) switches from C3 photosynthesis to an incomplete form of crassulacean acid metabolism (referred to as ‘CAM-idling’) when exposed to water stress (drought). This switch is accompanied by an increase in the activity of phosphoenolpyruvate carboxylase. This enzyme also shows several changes in properties, including a marked decrease in sensitivity to acid pH, a lower Km for phosphoenolpyruvate, very much decreased sensitivity to the allosteric inhibitor malate, and increased responsiveness to the allosteric effector glucose 6-phosphate. The Mr of the enzyme remains unchanged, at approx. 185 000. These changes in properties of phosphoenolpyruvate carboxylase are discussed in relation to the roles of the enzyme in C3 and in CAM plants.

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