Clanton C. Black

Ecological Implications of dividing Plants into Groups with Distinct Photosynthetic Production Capacities

Publisher Summary This chapter discusses the ecological implications of dividing plants in groups with distinct photosynthetic production capacities. The productivity of photosynthetic organisms is a fundamental factor in ecological relationships. It is observed that data on plant anatomy, plant physiology, and plant biochemistry have largely converged with the recognition of distinct groups of plants with several distinct characteristics including photosynthetic production capacity. One of the distinguishing characteristics of each plant group is the rate of net photosynthesis which in one major group of plants is two to threefold higher than the second major group of plants. This chapter describes the data which supports the concept of dividing plants in distinct groups in order to analyze some ecological implications and consequences of a particular division. The chapter also describes various criterias based on which the plants are divided in distinct group. These include anatomical, physiological, and biochemical criterias. In specific, the chapter considers photosynthetic capacity as a dominating factor in ecology. It states that solar energy is the major energy source and a plant which can add energy two to three times faster into an ecosystem than another plant must be considered when explaining or studying that ecosystem.

Vegetation dynamics of Mongolia.

Introduction to Studies on the Vegetation of Mongolia. Natural and Anthropogenic Factors and the Dynamics of Vegetation Distribution in Mongolia. 1.1. Introduction. 1.2. Natural Features of Mongolia. 1.3. Landscape-Ecological Regions. 1.4. Landscape and Ecological Factors of Vegetation Dynamics. 1.5. Conclusion. Late Quaternary Vegetation History of Mongolia. 2.1. Introduction. 2.2. An Overview of Previous Studies. 2.3. Data Used in this Study. 2.4. Regional Pollen Records from Individual Sites. 2.5. Holocene Changes in the Distribution of Tree and Shrub Taxa in Mongolia. 2.6. Spatial Reconstruction and Mapping of Mongolian Vegetation during the Last 15,000 Years. 2.7. General Discussion and Conclusions. Assessing Present-Day Plant Cover Dynamics. 3.1. Introduction. Modern Methods for Studying and Monitoring Plant Cover. 3.2. Mountain Plant Community Dynamics. 3.3. Plant Community Dynamics in Plains and Rocky Areas. 3.4. Dynamics of Water-Associated Vegetation. 3.5. Conclusions. Analysis of Present-Day Vegetation Dynamics. 4.1. Basic Changes in Vegetation. 4.2. Regressive Plant Community Successions. 4.3. Progressive Plant Community Regeneration. 4.4. Mapping Vegetation Dynamics. 4.5. Conclusions. Strategies for Nature Management and Vegetation Conservation. 5.1. Introduction. Methods for Vegetation Conservation. 5.2. Restoration and Conservation of Botanical Successions. 5.3. Systems for the Conservation of Botanical Diversity. 5.4. Conclusions. Summary Conclusions and Recommendations. References. Appendix 1. Appendix 2. Index.

C4 plants in the vegetation of Mongolia: their natural occurrence and geographical distribution in relation to climate

Abstract The natural geographical occurrence, carbon assimilation, and structural and biochemical diversity of species with C4 photosynthesis in the vegetation of Mongolia was studied. The Mongolian flora was screened for C4 plants by using 13C/12C isotope fractionation, determining the early products of 14CO2 fixation, microscopy of leaf mesophyll cell anatomy, and from reported literature data. Eighty C4 species were found among eight families: Amaranthaceae, Chenopodiaceae, Euphorbiaceae, Molluginaceae, Poaceae, Polygonaceae, Portulacaceae and Zygophyllaceae. Most of the C4 species were in three families: Chenopodiceae (41 species), Poaceae (25 species) and Polygonaceae, genus Calligonum (6 species). Some new C4 species in Chenopodiaceae, Poaceae and Polygonaceae were detected. C4 Chenopodiaceae species make up 45% of the total chenopods and are very important ecologically in saline areas and in cold arid deserts. C4 grasses make up about 10% of the total Poaceae species and these species naturally concentrate in steppe zones. Naturalized grasses with Kranz anatomy,of genera such as Setaria, Echinochloa, Eragrostis, Panicum and Chloris, were found in almost all the botanical-geographical regions of Mongolia, where they commonly occur in annually disturbed areas and desert oases. We analyzed the relationships between the occurrence of C4 plants in 16 natural botanical-geographical regions of Mongolia and their major climatic influences. The proportion of C4 species increases with decreasing geographical latitude and along the north-to-south temperature gradient; however grasses and chenopods differ in their responses to climate. The abundance of Chenopodiaceae species was closely correlated with aridity, but the distribution of the C4 grasses was more dependent on temperature. Also, we found a unique distribution of different C4 Chenopodiaceae structural and biochemical subtypes along the aridity gradient. NADP-malic enzyme (NADP-ME) tree-like species with a salsoloid type of Kranz anatomy, such as Haloxylon ammodendron and Iljinia regelii, plus shrubby Salsola and Anabasis species, were the plants most resistant to ecological stress and conditions in highly arid Gobian deserts with less than 100 mm of annual precipitation. Most of the annual C4 chenopod species were halophytes, succulent, and occurred in saline and arid environments in steppe and desert regions. The relative abundance of C3 succulent chenopod species also increased along the aridity gradient. Native C4 grasses were mainly annual and perennial species from the Cynodonteae tribe with NAD-ME and PEP-carboxykinase (PEP-CK) photosynthetic types. They occurred across much of Mongolia, but were most common in steppe zones where they are often dominant in grazing ecosystems.

The oxidative photosynthetic carbon cycle or C2 cycle

The oxidative photosynthetic carbon cycle (or C2 cycle) is the metabolic pathway responsible for photosynthetic oxygen uptake and the light‐dependent production of carbon dioxide that is termed photorespiration. The C2 and reductive C3 cycles coexist, and combined, represent total photosynthetic carbon metabolism. A brief historical review is presented beginning with the early observations of the oxygen inhibition of photosynthesis up to the discovery of the oxygenase activity associated with ribulose 1,5‐bisphosphate carboxylase/oxygenase. The properties and the role of the compartmentalization of the enzymes involved with the pathway and the transport of C2 cycle intermediates are reviewed. The relationship of the C2 cycle to photorespiratory nitrogen metabolism and other associated metabolic pathways and the properties and regulation of the C2 cycle in diverse photosynthetic organisms are discussed.

Pyrophosphate-dependent 6-phosphofructokinase, a new glycolytic enzyme in pineapple leaves

Abstract Pineapple leaves contain a pyrophosphate-dependent 6-phosphofructokinase which has been partially purified and characterized. In crude extracts the pyrophosphate-dependent activity is 10 to 20-fold higher than the ATP-dependent activity. The partially purified activity is near 2.5 μmol Fru-1,6- P 2 formed/min/mg protein. In the reaction 1 Fru-1,6- P 2 is formed per 1 pyrophosphate consumed. The enzyme exhibits a pH optimum of 8.0 and the activity is stimulated by Mg ++ . The discovery of a pyrophosphate-dependent 6-phosphofructokinase in pineapple leaves indicates pyrophosphate can serve as an energy source for synthetic reactions in pineapple and perhaps in other plants as well.

Phosphoenolpyruvate carboxykinase in leaves of certain plants which fix CO2 by the C4-dicarboxylic acid cycle of photosynthesis☆

Abstract Phosphoenolpyruvate carboxykinase has been found in leaves of Panicum maximum, Panicum texanum, and Sporobolus poiretii at levels sufficient to be involved in photosynthesis. The enzyme preferentially utilizes adenosine nucleotide derivatives. In Panicum maximum the enzyme is concentrated in the bundle sheath cells about four times higher than in the mesophyll cells. From 40 to 50 percent of the enzyme activity in bundle sheath cell extracts of Panicum maximum can be separated into a particulate fraction. The enzyme may function as a decarboxylase in bundle sheath cells of certain C4-dicarboxylic acid cycle plants which have a low content of malic enzyme.

Phylogenetic analysis of tribe Salsoleae (Chenopodiaceae) based on ribosomal ITS sequences: implications for the evolution of photosynthesis types

Diversity in photosynthetic pathways in the angiosperm family Chenopodiaceae is expressed in both biochemical and anatomical characters. To understand the evolution of photosynthetic diversity, we reconstructed the phylogeny of representative species of tribe Salsoleae of subfamily Salsoloideae, a group that exhibits in microcosm the patterns of photosynthetic variation present in the family as a whole, and examined the distribution of photosynthetic characters on the resulting phylogenetic tree. Phylogenetic relationships were inferred from parsimony analysis of nucleotide sequences of the internal transcribed spacer regions (ITS) of the 18S-26S nuclear ribosomal DNA of 34 species of Salsola and related genera (Halothamnus, Climacoptera, Girgensohnia, Halocharis, and Haloxylon) and representative outgroups from tribes Camphorosmeae (Camphorosma lessingii, Kochia prostrata, and K. scoparia) and Atripliceae (Atriplex spongiosa). A highly resolved strict consensus tree largely agrees with photosynthetic type and anatomy of leaves and cotyledons. The sequence data provide strong support for the origin and evolution of two main lineages of plants in tribe Salsoleae, with NAD-ME and NADP-ME C(4) photosynthesis, respectively. These groups have different C(4) photosynthetic types in leaves and different structural and photosynthetic characteristics in cotyledons. Phylogenetic relationships inferred from ITS sequences generally agree with classifications based on morphological data, but deviations from the existing taxonomy were also observed. The NAD-ME C(4) lineage contains species classified in sections Caroxylon, Malpigipila, Cardiandra, Belanthera, and Coccosalsola, and the NADP-ME lineage comprises species from sections Coccosalsola and Salsola. Reconstruction of photosynthetic characters on the ITS phylogeny indicates separate NAD-ME and NADP-ME lineages and suggests two reversions to C(3) photosynthesis. Reconstruction of geographic distributions suggests Salsoleae originated and diversified in central Asia and subsequently dispersed to Africa, Europe, and Mongolia. Inferred patterns and processes of photosynthetic evolution in Salsoleae should further our understanding of biochemical and anatomical evolution in Chenopodiaceae as a whole.

Biochemical and immunological properties of alkaline invertase isolated from sprouting soybean hypocotyls.

Alkaline invertase from sprouting soybean (Glycine max) hypocotyls was purified to apparent electrophoretic homogeneity by consecutive use of DEAE-cellulose, green 19 dye, and Cibacron blue 3GA dye affinity chromatography. This protocol produced about a 100-fold purification with about a 11% yield. The purified protein had a specific activity of 48 mumol of glucose produced mg-1 protein min-1 (pH 7.0) and showed a single protein band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (PAGE) (58 kDa) and in native PAGE, as indicated by both protein and activity staining. The native enzyme molecular mass was about 240 kDa, suggesting a homotetrameric structure. The purified enzyme exhibited hyperbolic saturation kinetics with a Km (sucrose) near 10 mM and the enzyme did not utilize raffinose, maltose, lactose, or cellibose as a substrate. Impure alkaline invertase preparations, which contained acid invertase activity, on contrast, showed biphasic curves versus sucrose concentration. Combining equal activities of purified alkaline invertase with acid invertase resulted in a biphasic response, but there was a transition to hyperbolic saturation kinetics when the activity ratio, alkaline: acid invertase, was increased above unity. Alkaline invertase activity was inhibited by HgCl2, pridoxal phosphate, and Tris with respective Ki values near 2 microM, 5 microM, and 4 mM. Glycoprotein staining (periodic acid-Schiff method) was negative and alkaline invertase did not bind to two immobilized lectins, concanavalin A and wheat germ agglutinin; hence, the enzyme apparently is not a glycoprotein. The purified alkaline invertase, and a purified soybean acid invertase, was used to raise rabbit polyclonal antibodies. The alkaline invertase antibody preparation was specific for alkaline invertase and cross-reacted with alkaline invertases from other plants. Neither purified soybean alkaline invertases nor the crude enzyme from several plants cross-reacted with the soybean acid invertase antibody.

Occurrence of C3 and C4 photosynthesis in cotyledons and leaves of Salsola species (Chenopodiaceae)

Most species of the genus Salsola (Chenopodiaceae) that have been examined exhibit C4 photosynthesis in leaves. Four Salsola species from Central Asia were investigated in this study to determine the structural and functional relationships in photosynthesis of cotyledons compared to leaves, using anatomical (Kranz versus non-Kranz anatomy, chloroplast ultrastructure) and biochemical (activities of photosynthetic enzymes of the C3 and C4 pathways, 14C labeling of primary photosynthesis products and 13C/12C carbon isotope fractionation) criteria. The species included S. paulsenii from section Salsola, S. richteri from section Coccosalsola, S. laricina from section Caroxylon, and S. gemmascens from section Malpigipila. The results show that all four species have a C4 type of photosynthesis in leaves with a Salsoloid type Kranz anatomy, whereas both C3 and C4 types of photosynthesis were found in cotyledons. S. paulsenii and S. richteri have NADP- (NADP-ME) C4 type biochemistry with Salsoloid Kranz anatomy in both leaves and cotyledons. In S. laricina, both cotyledons and leaves have NAD-malic enzyme (NAD-ME) C4 type photosynthesis; however, while the leaves have Salsoloid type Kranz anatomy, cotyledons have Atriplicoid type Kranz anatomy. In S. gemmascens, cotyledons exhibit C3 type photosynthesis, while leaves perform NAD-ME type photosynthesis. Since the four species studied belong to different Salsola sections, this suggests that differences in photosynthetic types of leaves and cotyledons may be used as a basis or studies of the origin and evolution of C4 photosynthesis in the family Chenopodiaceae.

Metabolism of epidermal tissues, mesophyll cells, and bundle sheath strands resolved from mature nutsedge leaves☆

Abstract Mesophyll cells and bundle sheath strands were isolated from Cyperus rotundus L. leaf sections infiltrated with a mixture of cellulase and pectinase followed by a gentle mortar and pestle grind. The leaf suspension was filtered through a filter assembly and mesophyll cells and bundle sheath strands were collected on 20-μm and 80-μm nylon nets, respectively. For the isolation of leaf epidermal strips longer leaf cross sections were incubated with the enzymes and gently ground as above. Loosely attached epidermal strips were peeled off with forceps. The upper epidermis, which lacks stomata, could be clearly distinguished from the lower epidermis which contains stomata. Microscopic evidence for identification and assessment of purity is provided for each isolated tissue. Enzymes related to the C4-dicarboxylic acid cycle such as phosphoenolpyruvate carboxylase, malate dehydrogenase (NADP+), pyruvate, Pi dikinase were found to be localized, ≥98%, in mesophyll cells. Enzymes related to operating the reductive pentose phosphate cycle such as RuDP carboxylase, phosphoribulose kinase, and malic enzyme are distributed, ≥99%, in bundle sheath strands. Other photosynthetic enzymes such as aspartate aminotransferase, pyrophosphatase, adenylate kinase, and glyceraldehyde 3-P dehydrogenase (NADP+) are quite active in both mesophyll and bundle sheath tissues. Enzymes involved in photorespiration such as RuDP oxygenase, catalase, glycolate oxidase, hydroxypyruvate reductase (NAD+), and phosphoglycolate phosphatase are preferentially localized, ≥84%, in bundle sheath strands. Nitrate and nitrite reductase can be found only in mesophyll cells, while glutamate dehydrogenase is present, ≥96%, in bundle sheath strands. Starch- and sucrose-synthesizing enzymes are about equally distributed between the mesophyll and bundle sheath tissues, except that the less active phosphorylase was found mainly in bundle sheath strands. Fructose-1,6-diP aldolase, which is a key enzyme in photosynthesis and glycolysis leading to sucrose and starch synthesis, is localized, ≥90%, in bundle sheath strands. The glycolytic enzymes, phosphoglyceromutase and enolase, have the highest activity in mesophyll cells, while the mitochondrial enzyme, cytochrome c oxidase, is more active in bundle sheath strands. The distribution of total nutsedge leaf chlorophyll, protein, and PEP carboxylase activity, using the resolved leaf components, is presented. 14CO2 Fixation experiments with the intact nutsedge leaves and isolated mesophyll and bundle sheath tissues show that complete C4 photosynthesis is compartmentalized into mesophyll CO2 fixation via PEP carboxylase and bundle sheath CO2 fixation via RuDP carboxylase. These results were used to support the proposed pathway of carbon assimilation in C4-dicarboxylic acid photosynthesis and to discuss the individual metabolic characteristics of intact mesophyll cells, bundle sheath cells, and epidermal tissues.